Classification of Elements and Periodicity in Properties ?

The classification of elements and the periodicity of their properties are fundamental concepts in chemistry. These ideas were developed based on the observation of trends in the behavior and characteristics of elements as they are arranged in a systematic manner. Here’s a breakdown:

1. Classification of Elements:

Elements are classified into different groups based on their atomic structure, properties, and periodicity. This classification forms the basis of the Periodic Table.

A. Periodic Table:

The periodic table organizes elements into periods (rows) and groups (columns). There are:

• Groups: 18 vertical columns that contain elements with similar chemical properties.
  • Group 1: Alkali metals (e.g., lithium, sodium)
  • Group 2: Alkaline earth metals (e.g., magnesium, calcium)
  • Groups 17: Halogens (e.g., fluorine, chlorine)
  • Group 18: Noble gases (e.g., helium, neon)
• Periods: 7 horizontal rows, where each period represents a new electron shell being added to the atoms of the elements in that row.

B. Classification Based on Element Type:

• Metals: Good conductors of heat and electricity (e.g., iron, copper).
• Nonmetals: Poor conductors, often brittle in solid form (e.g., oxygen, sulfur).
• Metalloids: Have properties intermediate between metals and nonmetals (e.g., silicon, arsenic).

C. Blocks:

• s-block: Groups 1 and 2, and helium in Group 18.
• p-block: Groups 13 to 18.
• d-block: Transition metals (Groups 3 to 12).
• f-block: Lanthanides and actinides.

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2. Periodicity in Properties:

Periodicity refers to the repeating trends observed in the properties of elements as you move across a period or down a group in the periodic table. These trends include:

A. Atomic Radius:

• Across a period (left to right): The atomic radius decreases due to an increase in nuclear charge, which pulls electrons closer to the nucleus.
• Down a group: The atomic radius increases because additional electron shells are added, increasing the distance between the nucleus and the outermost electron.

B. Ionization Energy:

Ionization energy is the energy required to remove an electron from an atom.

• Across a period: Ionization energy increases because the effective nuclear charge increases, holding the electrons more tightly.
• Down a group: Ionization energy decreases as the atomic radius increases, and the outer electrons are farther from the nucleus, requiring less energy to be removed.

C. Electron Affinity:

Electron affinity is the energy change when an electron is added to a neutral atom.

• Across a period: Generally, electron affinity becomes more negative (i.e., the atom more readily accepts an electron).
• Down a group: The electron affinity becomes less negative (less energy is released when an electron is added).

D. Electronegativity:

Electronegativity is the tendency of an atom to attract electrons in a chemical bond.

• Across a period: Electronegativity increases due to the increased nuclear charge attracting bonding electrons.
• Down a group: Electronegativity decreases because the additional electron shells reduce the attraction between the nucleus and the bonding electrons.

E. Melting and Boiling Points:

• Across a period: The melting and boiling points generally increase for metals but can decrease for nonmetals.
• Down a group: Melting and boiling points tend to decrease for metals and increase for nonmetals, though the trends can vary.

F. Chemical Reactivity:

• Metals: Reactivity increases as you go down a group because it’s easier to lose electrons from larger atoms.
• Nonmetals: Reactivity increases across a period, particularly for nonmetals, as their ability to gain electrons increases.

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In conclusion, the periodic classification of elements helps to predict and explain various chemical properties and behaviors based on the position of an element in the periodic table. Periodicity itself reflects the recurring trends in the atomic and physical properties of the elements.

What is Classification of Elements and Periodicity in Properties ?

Classification of Elements:

The classification of elements refers to organizing elements based on their similar properties, electron configurations, and atomic structure. This organization helps understand the trends in their chemical and physical behaviors. The most common system used for classification is the Periodic Table of Elements.

1. Periodic Table Structure:

The periodic table arranges elements in rows (called periods) and columns (called groups or families) based on their atomic numbers.

• Periods: There are 7 periods in the periodic table. A period represents the filling of electron shells in an atom. As we move across a period from left to right, elements gradually change from metals to nonmetals.
• Groups: There are 18 groups in the periodic table. Elements in the same group have similar chemical properties because they have the same number of electrons in their outermost shell.

2. Types of Elements:

• Metals: Elements that are typically good conductors of heat and electricity. They tend to lose electrons in chemical reactions. Examples: iron, copper, and gold.
• Nonmetals: Elements that are poor conductors of heat and electricity and tend to gain electrons in chemical reactions. Examples: oxygen, nitrogen, and sulfur.
• Metalloids: Elements that have properties intermediate between metals and nonmetals. Examples: silicon, arsenic, and germanium.

3. Blocks in the Periodic Table:

• s-block: Groups 1 and 2, plus hydrogen and helium. These elements have their valence electrons in s-orbitals.
• p-block: Groups 13 to 18. These elements have their valence electrons in p-orbitals.
• d-block: Transition metals, located in groups 3 to 12. These elements have their valence electrons in d-orbitals.
• f-block: Lanthanides and actinides, which are placed below the main body of the periodic table. These elements have their valence electrons in f-orbitals.

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Periodicity in Properties:

Periodicity refers to the recurring trends in the properties of elements as we move across a period or down a group in the periodic table. These trends are a result of the periodic variation in atomic structure.

1. Atomic Radius:

• Across a period: The atomic radius decreases because the number of protons in the nucleus increases, which pulls the electrons closer to the nucleus, reducing the size of the atom.
• Down a group: The atomic radius increases because new electron shells are added, which makes the atom larger and the outermost electrons farther from the nucleus.

2. Ionization Energy:

Ionization energy is the energy required to remove an electron from an atom.

• Across a period: Ionization energy increases because the atoms become smaller, and the outer electrons are held more tightly by the nucleus.
• Down a group: Ionization energy decreases because the outer electrons are farther from the nucleus and experience more shielding from inner electrons.

3. Electron Affinity:

Electron affinity refers to the energy change when an electron is added to a neutral atom.

• Across a period: Electron affinity becomes more negative (i.e., more energy is released) because the atoms have a stronger attraction for added electrons.
• Down a group: Electron affinity becomes less negative (less energy is released) because the added electron is farther from the nucleus and less attracted.

4. Electronegativity:

Electronegativity is a measure of an atom’s ability to attract electrons in a chemical bond.

• Across a period: Electronegativity increases because the effective nuclear charge increases, attracting electrons more strongly.
• Down a group: Electronegativity decreases because the atoms are larger, and the attraction between the nucleus and bonding electrons weakens.

5. Melting and Boiling Points:

• Across a period: Melting and boiling points generally increase for metals, but may decrease for nonmetals as you move across a period.
• Down a group: Melting and boiling points tend to increase for metals (because the size of the atoms increases), but they may decrease for nonmetals.

6. Reactivity:

• For metals: Reactivity increases as you go down a group because the outer electrons are farther from the nucleus and more easily lost.
• For nonmetals: Reactivity increases as you go across a period (from left to right) because atoms have a stronger ability to gain electrons.

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Conclusion:

The classification of elements and periodicity in properties are key concepts in chemistry that help organize elements and predict their behaviors based on their position in the periodic table. These periodic trends allow us to understand how elements will react and interact, making them essential in studying chemical reactions, atomic structure, and material properties.

Who is required Classification of Elements and Periodicity in Properties ?

The concepts of Classification of Elements and Periodicity in Properties are crucial for a wide range of individuals and fields, including those involved in scientific research, education, industry, and various specialized applications. Here are some groups that require understanding these concepts:

1. Chemists:

• Inorganic Chemists: They study the properties and behaviors of elements and compounds, so understanding their classification and periodic trends is essential to predict reactions, bond formation, and molecular behavior.
• Analytical Chemists: They use the periodic trends to identify unknown substances and understand how different elements interact in chemical processes.

2. Students (Science & Engineering):

• High School and College Students: Particularly in chemistry courses, students need to grasp the classification of elements and the periodic trends to perform well in exams and practical experiments.
• Graduate Students and Researchers: Advanced study in chemistry, physics, or materials science involves understanding the periodic table for research and exploration of new materials or reactions.

3. Teachers and Educators:

• Chemistry Teachers/Professors: Teachers must explain the periodic table, classification of elements, and periodicity to students in a clear and accurate manner. Understanding these concepts is fundamental to effective teaching in schools and universities.

4. Scientists and Researchers:

• Materials Scientists: Understanding periodic trends is essential for selecting appropriate materials based on their properties, such as conductivity, strength, or reactivity.
• Physicists: Periodicity plays a role in atomic structure, quantum mechanics, and the behavior of matter at the atomic level.
• Biochemists and Molecular Biologists: Understanding the properties of elements helps in areas such as enzyme function, protein synthesis, and the behavior of biomolecules.

5. Engineers:

• Chemical Engineers: They use the periodic trends to design processes for producing chemicals, pharmaceuticals, or petrochemicals. Knowledge of how elements react helps in optimizing reactions and selecting catalysts.
• Materials Engineers: Periodicity helps them choose materials with the right properties for manufacturing and construction, such as metals, polymers, and composites.

6. Pharmacists and Pharmacologists:

• Drug Development: Understanding the periodic table and element classification helps in developing drugs that interact with biological systems at the molecular and atomic levels.

7. Environmental Scientists:

• Pollution Control: Knowledge of periodicity helps in tracking pollutants and understanding the behavior of elements in natural processes, such as water cycles or soil contamination.

8. Industrial Applications:

• Metallurgists: They work with metals and alloys, where understanding the periodic trends helps in choosing the correct materials for various industrial applications (e.g., aerospace, automotive, construction).
• Nanotechnology Engineers: Understanding the properties of elements on a very small scale helps in designing new materials and devices, such as nanomaterials, sensors, and drug delivery systems.

9. Pharmacists and Healthcare Professionals:

• In medicine and pharmacy, understanding the classification of elements and their properties is essential when developing medical treatments, medications, or diagnostic tools.

10. Geologists:

• Earth Scientists: The study of elements and their periodic properties is critical in understanding the Earth’s composition, mineral formation, and how different elements interact in the Earth’s crust.

Conclusion:

The Classification of Elements and Periodicity in Properties are fundamental concepts not only for chemistry students and professionals but also for a wide range of scientific and engineering disciplines. Understanding these principles is crucial for anyone involved in the analysis, application, or development of chemical substances, materials, and technologies.

When is required Classification of Elements and Periodicity in Properties ?

The Classification of Elements and Periodicity in Properties are required at various stages and in different contexts, particularly when understanding or dealing with the behavior of elements, their interactions, and the design of experiments, processes, or materials. Here are the key instances when these concepts are required:

1. In Educational Settings:

• During Chemistry Lessons (High School and College):
  • When students are introduced to the periodic table, they learn about the classification of elements (metals, nonmetals, metalloids) and how elements are organized by atomic number and electron configuration.
  • Periodicity in properties (such as atomic radius, ionization energy, electronegativity) is essential for understanding trends across periods and groups.
• When Studying Atomic Structure and Bonding:
  • Students learn how the classification of elements helps predict the formation of bonds, reactivity, and molecular structures based on the periodic trends.
• In Graduate or Postgraduate Research:
  • Researchers often explore how the periodic trends influence the design of new compounds, catalysts, and materials.

2. In Scientific Research and Experimentation:

• In Material Science and Chemistry Research:
  • When developing or studying new materials (e.g., semiconductors, alloys, polymers), researchers rely on periodic trends to predict the properties of materials and their suitability for specific applications.
  • The classification of elements helps identify which elements will combine to form certain compounds with desirable properties.
• In Chemical Reactions:
  • Understanding periodicity helps predict the reactivity of different elements and compounds, particularly in designing controlled chemical reactions for industrial processes, laboratories, or pharmaceuticals.

3. In Industrial and Engineering Applications:

• Chemical Engineering:
  • When designing processes that involve specific chemical reactions or the synthesis of materials, understanding periodic trends helps in selecting appropriate elements or compounds that will react under certain conditions.
• Materials Engineering:
  • Engineers need to know which elements and their periodic properties determine the strength, conductivity, and other key features of materials. For example, knowing how the atomic radius and electronegativity influence the behavior of metals or alloys is crucial for applications in aerospace, electronics, and construction.
• Environmental Engineering:
  • When studying pollutant behavior, environmental scientists use periodicity to understand how elements like metals or gases behave in soil, water, and air. This helps in designing efficient waste management or pollution control systems.

4. In Pharmacology and Biochemistry:

• Drug Development and Design:
  • Pharmacologists and biochemists use periodic trends to understand how different elements interact at the molecular level in biological systems. The classification of elements helps in predicting the biological activity of compounds.
• Understanding Bioavailability and Toxicity:
  • The periodic properties of elements can influence how certain substances are absorbed or metabolized by the body, as well as their toxicity levels.

5. In Environmental and Earth Sciences:

• Geology and Mineralogy:
  • Geologists use periodicity to study the Earth’s elements and how they form minerals or ore deposits. The classification of elements helps to understand the composition of the Earth’s crust and the processes that shape our planet.

6. In Industrial Manufacturing and Metallurgy:

• Metal Production:
  • Metallurgists need to understand the periodic classification of elements and the periodic trends when selecting metals for various applications (e.g., lightweight alloys, corrosion resistance).
• Electronics Industry:
  • The periodic trends of elements like silicon, germanium, and gallium are essential for the design of semiconductors and other electronic components.

7. In Biotechnology and Nanotechnology:

• Nanotechnology:
  • Researchers in nanotechnology study the properties of elements at the atomic scale, where periodicity plays a critical role in designing nanomaterials and nanodevices with desired properties.
• Biotechnology:
  • Understanding periodic trends is also important in biotechnology, where the interactions between different elements can influence enzyme activity, genetic expression, or the development of new diagnostic tools.

8. When Analyzing the Behavior of Elements:

• Predicting Chemical Behavior:
  • In daily laboratory work, chemists rely on periodic trends to predict how elements will react under certain conditions, such as acid-base reactions, redox reactions, and more.
• Developing Chemical Formulas:
  • The classification and periodic properties of elements help in determining the stoichiometry of chemical reactions and the formation of molecular formulas.

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Conclusion:

The Classification of Elements and Periodicity in Properties are required whenever there is a need to:

• Predict the behavior, reactions, and interactions of elements or compounds.
• Understand trends in chemical and physical properties for applications in research, industry, or healthcare.
• Design and select materials, products, or processes based on element behavior.
• Teach or learn foundational principles of chemistry, material science, and related fields.

These concepts are essential across scientific, industrial, educational, and healthcare domains whenever the properties and interactions of elements need to be understood or predicted.

Where is required Classification of Elements and Periodicity in Properties ?

The Classification of Elements and Periodicity in Properties are required in a variety of settings and disciplines. These concepts are critical wherever the behavior, interactions, and properties of elements and compounds need to be understood, applied, or predicted. Below are key areas and places where these concepts are required:

1. Educational Institutions:

• Schools and Colleges:
  • In chemistry classrooms around the world, especially in high schools and colleges, students learn the classification of elements and periodic trends to build a foundational understanding of chemistry.
  • Laboratories in educational settings require an understanding of periodicity to conduct experiments related to chemical reactions, element properties, and bonding.
• Universities and Research Institutes:
  • Graduate students and researchers studying inorganic chemistry, material science, or pharmacology rely on these concepts for advanced research projects, where periodicity plays a role in predicting material behaviors or reactions.

2. Research and Development Labs:

• Chemical Research Laboratories:
  • In research labs focused on chemical synthesis, reaction mechanisms, or new compounds, understanding periodicity helps predict how elements will interact or bond under various conditions.
• Materials Science Laboratories:
  • In materials research, the periodic classification helps in selecting materials with the right physical, chemical, and electrical properties, including for semiconductors, alloys, and composites.
• Pharmaceutical Research:
  • In drug discovery and development, understanding the chemical properties of elements is essential for designing effective pharmaceuticals and predicting how they will interact with biological systems.

3. Industries:

• Chemical Manufacturing Industry:
  • Chemical plants and manufacturing facilities that produce chemicals, plastics, or pharmaceuticals need to consider periodic trends to optimize reactions, select catalysts, and improve product quality.
• Materials and Metallurgy Industry:
  • The metals industry, including steel production, alloy production, and nano-material manufacturing, requires knowledge of periodicity to select appropriate materials based on strength, flexibility, and conductivity.
• Semiconductor Industry:
  • The electronics industry uses periodicity to design semiconductors and select materials with specific electrical properties. For example, silicon’s behavior as a semiconductor is predicted by its position in the periodic table.

4. Engineering and Design:

• Civil and Mechanical Engineering:
  • Engineers use periodicity to select building materials (e.g., metals, alloys) that must withstand specific conditions such as temperature, pressure, or electrical conductivity.
• Chemical Engineering:
  • In chemical process design, engineers apply the periodic trends of elements to design reactors, distillation columns, and separation processes based on element reactivity, boiling points, and solubility.

5. Environmental and Earth Sciences:

• Environmental Engineering:
  • In pollution control, understanding how elements behave in nature, such as how metals might interact with soil or water, is crucial for mitigating contamination and protecting ecosystems.
• Geology and Mineralogy:
  • Geologists need to understand periodic trends to interpret the Earth’s crust composition and identify ore deposits, minerals, and other geological features based on their element composition.

6. Healthcare and Biotechnology:

• Pharmacology and Medicine:
  • Pharmacists, doctors, and biochemists use the classification and periodic properties of elements to develop drugs and medical devices. For example, understanding the properties of metals and nonmetals helps in drug design and understanding their biological effects.
• Biotechnology Labs:
  • In genetic engineering, biotech researchers use the properties of elements to modify proteins, enzymes, and other molecules for specific applications like gene therapy or diagnostics.

7. Government and Regulatory Bodies:

• Standardization and Safety Protocols:
  • Regulatory bodies such as the EPA (Environmental Protection Agency) or OSHA (Occupational Safety and Health Administration) use periodic properties to set standards for handling chemicals, environmental safety, and exposure limits based on elemental toxicity or reactivity.

8. Astronomy and Space Research:

• Astronomers and Astrophysicists:
  • When studying the composition of stars, planets, and asteroids, scientists use the periodic table to predict and understand the behavior of elements in extreme environments (e.g., high temperatures and pressures in stellar cores).

9. Military and Defense:

• Weapons Development:
  • Understanding the periodic properties of elements is critical in developing military technologies, such as advanced materials for armor, explosives, and nuclear weapons.

10. Nanotechnology and Quantum Computing:

• Nanotechnology Research Centers:
  • Nanotechnologists rely on periodic properties to manipulate individual atoms or molecules and design materials at the nanoscale, with applications in electronics, medicine, and energy storage.
• Quantum Computing Labs:
  • In quantum computing, understanding how elements and their periodic properties behave on the atomic level is crucial for designing quantum processors and other cutting-edge technologies.

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Conclusion:

The Classification of Elements and Periodicity in Properties are required in places where understanding chemical behavior, predicting reactions, designing new materials, or developing new technologies is necessary. This spans across:

• Educational institutions for teaching and learning.
• Research labs for discovering new compounds or materials.
• Industries for manufacturing and application.
• Environmental and healthcare sectors for safety and drug development.
• Engineering fields for material selection and process design.

These concepts are universally applicable wherever the chemical and physical properties of elements influence real-world applications

How is required Classification of Elements and Periodicity in Properties ?

The Classification of Elements and Periodicity in Properties are required in various ways across different fields. They form the foundation for understanding how elements behave, how they interact with each other, and how their properties change across periods and groups in the periodic table. Here’s a breakdown of how these concepts are required in different contexts:

1. In Education and Teaching:

• Foundational Understanding:
  • In schools and colleges, the classification of elements and periodicity are required to introduce students to the basic principles of chemistry. The periodic table helps organize elements, and periodic trends provide insights into atomic size, ionization energy, electronegativity, and other important properties.
• Simplifying Complex Concepts:
  • By using periodicity, educators simplify complex chemical behavior, such as trends in atomic radius or reactivity. This helps students predict the properties and reactivity of elements, which is essential for learning about chemical reactions and bonding.

2. In Scientific Research:

• Predicting Elemental Behavior:
  • Researchers rely on periodicity to predict the chemical behavior of elements. For instance, the periodic trends in ionization energy or electronegativity can help predict how elements will react in different chemical reactions. This is crucial in chemical synthesis, material development, and biochemistry.
• Designing Experiments:
  • Scientists use periodicity to design experiments that test specific properties of elements or compounds. For example, understanding the periodic table helps researchers design catalysts, analyze chemical reactions, and predict outcomes based on known elemental properties.

3. In Industrial and Manufacturing Applications:

• Material Selection:
  • Engineers use the classification and periodic trends to select the right materials for specific applications. For example, in metallurgy, knowledge of periodicity helps in the selection of metals and alloys with desired properties (e.g., strength, conductivity, corrosion resistance).
• Optimizing Chemical Processes:
  • In industries like chemical manufacturing, understanding periodicity is essential for optimizing reactions. For instance, selecting appropriate catalysts, predicting reaction rates, and understanding how elements will behave under various conditions (such as temperature or pressure) all rely on periodic properties.

4. In Environmental and Earth Sciences:

• Studying Elemental Distribution:
  • In geology and mineralogy, periodicity helps understand the distribution of elements in the Earth’s crust. Elements in similar groups often exhibit similar behaviors, helping geologists locate and predict mineral deposits or ore formations.
• Environmental Impact Predictions:
  • Understanding how elements interact with the environment is crucial in environmental science. For example, periodicity helps in predicting how heavy metals (like lead, mercury) behave in water, soil, and the atmosphere, which is essential for assessing environmental pollution and toxicity.

5. In Materials Science and Engineering:

• Designing New Materials:
  • Materials scientists use periodicity to design materials with specific properties. For example, the conductivity of metals is often predicted based on periodic trends. The periodic classification also helps in designing semiconductors, superconductors, and alloys by predicting how elements will bond and behave under stress or heat.
• Tailoring Properties:
  • By understanding periodic trends, materials engineers can tailor the properties of materials, such as strength, ductility, and conductivity, to meet the needs of specific applications like aerospace, automotive, and electronics.

6. In Healthcare and Pharmacology:

• Drug Design and Interaction:
  • Pharmacologists and biochemists rely on the periodicity of elements to predict how drugs interact with the body. For example, understanding how the electronegativity or atomic size of elements affects enzyme activity or the binding of drugs to receptors is essential for drug development.
• Toxicity Studies:
  • The toxicity of certain elements (like heavy metals) is predicted based on their position in the periodic table. This knowledge helps in assessing the safety of materials and chemicals in medicines, food, or environmental contaminants.

7. In Nanotechnology:

• Manipulating Elemental Properties at the Nano Scale:
  • Nanotechnologists use periodic trends to understand how the properties of elements change at the nanoscale. For example, the behavior of carbon atoms in graphene or other nanomaterials is influenced by their position in the periodic table, and periodicity helps predict their mechanical and electronic properties.
• Designing Nanomaterials:
  • Nanomaterials are designed with specific properties by selecting elements based on their periodic properties. Understanding trends like atomic size, ionization energy, and electronegativity helps engineers create materials for specific applications like sensors, drug delivery, or energy storage.

8. In Chemical Engineering:

• Catalysis and Reaction Design:
  • Chemical engineers use periodic trends to predict the efficiency of different catalysts in industrial processes. The classification of elements into metals, nonmetals, and metalloids helps identify which materials will act as effective catalysts under specific conditions.
• Reaction Kinetics and Product Design:
  • By understanding the periodic trends in reactivity and bonding, engineers can design more efficient chemical reactions. The periodic table allows them to predict which elements are likely to participate in certain types of reactions, aiding in the development of new products.

9. In Biotechnology:

• Understanding Molecular Interactions:
  • In biotechnology, understanding how elements like oxygen, nitrogen, and carbon interact at the molecular level is key to developing new techniques in gene therapy, enzyme catalysis, and DNA sequencing.
• Biological Pathways and Drug Interactions:
  • The periodic trends help biotechnologists understand how elements influence biological pathways and reactions within cells. For example, transition metals often play a role in enzymes, and their properties are essential for developing specific biotechnological applications.

10. In Environmental Health and Safety:

• Predicting Element Behavior in Different Environments:
  • In safety protocols, periodicity helps predict how elements behave in different environments (e.g., how certain elements might act in acidic or basic conditions). This is crucial for handling and storing chemicals safely.
• Regulatory Compliance:
  • Governments and regulatory bodies use the periodicity of elements to create safety standards and guidelines. For example, the classification of elements into metals and nonmetals helps in setting guidelines for exposure limits and environmental contamination.

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Conclusion:

The Classification of Elements and Periodicity in Properties are required in a variety of ways:

• To predict and understand the behavior of elements (e.g., reactivity, bonding, properties).
• To design experiments, materials, and technologies based on elemental properties.
• To optimize industrial processes, improve safety, and enhance product performance.
• To assess environmental impacts and develop safer, more efficient materials and processes in healthcare, technology, and engineering.

These concepts serve as the backbone of many scientific, industrial, and educational practices, facilitating progress and innovation across multiple fields.

Case study is Classification of Elements and Periodicity in Properties ?

Case Study: Classification of Elements and Periodicity in Properties

Introduction:

The classification of elements and periodicity in their properties are fundamental concepts in chemistry that help explain the behavior of elements across the periodic table. Understanding these principles allows scientists, engineers, and researchers to predict the behavior of elements and design systems or materials that rely on these properties. This case study highlights how the periodic table’s classification and the periodicity in properties were applied in a practical scenario in the chemical industry to improve the production of a specific material, steel.

Background:

In the steel industry, the properties of materials, especially metals, are crucial for manufacturing products that meet safety, durability, and strength standards. Steel, an alloy primarily composed of iron with small amounts of carbon, often includes other elements like manganese, chromium, and nickel to improve its properties. The periodic table provides insights into how these elements behave when mixed and how their properties change.

The periodicity of elements—such as atomic size, electronegativity, ionization energy, and metallic character—plays a crucial role in understanding how these elements interact with one another and with the surrounding environment. In this case, the goal was to use knowledge of periodicity and classification to optimize the steelmaking process.

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Case Study: Optimizing Steel Production

Challenge:

A steel manufacturing company was facing challenges in producing high-strength steel that would meet the safety requirements for construction projects. While the company used a standard formula for making steel, variations in the quality of steel were noticed depending on the addition of trace elements like manganese, chromium, and nickel. The company wanted to understand how different elements and their positions on the periodic table could be used to improve the steel’s strength, corrosion resistance, and flexibility.

Application of Classification and Periodicity:

1. Periodic Table and Group Trends:
   • Manganese (Mn): Manganese is placed in Group 7 of the periodic table. It has a relatively low ionization energy and is known to form +2 and +4 oxidation states. The periodicity in its properties shows that it can help in improving the toughness of steel, by preventing the formation of carbides, which could lead to brittleness.
   • Chromium (Cr): Chromium is a transition metal in Group 6 and is known for its strong metallic bond and ability to form protective oxide layers. Its periodic properties, such as high melting point and corrosion resistance, make it ideal for creating stainless steel with enhanced durability.
   • Nickel (Ni): Nickel, in Group 10, is highly resistant to corrosion and enhances the toughness and strength of steel, especially in cold environments. The periodic trend of high electronegativity and strong metal bonding explains its effectiveness in improving the steel’s overall properties.
2. Periodicity and Reactivity:
   • By understanding the reactivity trend across the periodic table, the company realized that adding manganese to the steel composition could help control the reactivity of iron. Manganese acts as a deoxidizer and helps remove impurities, resulting in cleaner, stronger steel.
   • The ionization energy of elements like chromium allows it to resist corrosion, making it ideal for environments that are exposed to moisture and air, improving the steel’s longevity.
3. Atomic Size and Alloying:
   • The periodicity in atomic size also played a role. Smaller elements like carbon (in steel) fit easily between iron atoms in the crystal lattice, increasing the steel’s hardness. However, large elements like manganese and chromium were found to interact with iron in a way that altered the atomic arrangement, giving the steel better strength without compromising flexibility.
4. Electronegativity and Bonding:
   • The electronegativity of elements such as chromium and nickel affected how well these elements bonded with carbon and iron in the steel. This understanding of periodic trends helped the company determine the ideal mixture of elements for specific steel products, such as those required for construction, aerospace, or automotive applications.

Solution and Results:

By applying the knowledge of classification and periodicity in properties, the company optimized its steelmaking formula by adjusting the proportions of manganese, chromium, and nickel based on their periodic properties:

• Increased Manganese content led to higher toughness and resistance to wear.
• Chromium was added to increase corrosion resistance, especially in steel used for outdoor structures.
• Nickel was included to improve the overall flexibility and cold resistance of steel.

The company tested various alloys and observed how the periodic trends in atomic size, ionization energy, and electronegativity influenced the final product. The results showed that steel with a balanced composition of these elements exhibited:

• Improved strength and durability,
• Enhanced corrosion resistance (especially important for outdoor and marine applications),
• Increased ductility and toughness, even under extreme temperatures.

Conclusion:

This case study highlights how the classification of elements and the periodicity in their properties were key to optimizing a material for specific industrial applications. By understanding how elements behave and interact based on their positions in the periodic table, the steel manufacturer was able to produce a better quality product, meet safety standards, and improve performance in the construction and manufacturing industries.

The case demonstrates the importance of periodicity not only in academic chemistry but also in real-world applications where material properties are critical for performance and safety.

White paper on Classification of Elements and Periodicity in Properties ?

White Paper: Classification of Elements and Periodicity in Properties

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Abstract

The classification of elements and the periodicity in their properties form the foundation of modern chemistry and materials science. By understanding the periodic trends of elements, scientists and engineers can predict the behavior of elements and their compounds. This white paper explores the principles of classification of elements, periodic trends in properties, and their significance in various scientific and industrial applications. The objective is to provide a comprehensive overview of how these concepts are essential in fields ranging from materials science to pharmaceuticals, and environmental studies.

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Introduction

The periodic table, a systematic arrangement of elements, plays a pivotal role in chemistry. The arrangement is based on the elements’ atomic numbers, electron configurations, and recurring chemical properties. The classification of elements helps in understanding the periodicity of their properties, which provides valuable insights into how elements interact with each other, and how their properties change across periods and groups.

Periodic trends are observable patterns in the properties of elements as one moves across a period or down a group. These trends allow chemists to predict the reactivity, physical characteristics, and other significant behaviors of elements. The periodicity in properties refers to these predictable changes in characteristics such as atomic size, ionization energy, electronegativity, electron affinity, and metallic character.

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1. Classification of Elements

The classification of elements is based on their atomic structure, electron configuration, and recurring chemical behaviors. Elements are divided into the following categories:

• Metals, Non-metals, and Metalloids: Metals are generally conductive, malleable, and have a high melting point, while non-metals are poor conductors and often brittle. Metalloids have properties intermediate between metals and non-metals.
• Groups and Periods: The periodic table is arranged in groups (vertical columns) and periods (horizontal rows). Elements in the same group share similar chemical properties due to their similar electron configurations.
• S, P, D, and F Blocks: These blocks represent the type of orbitals that are being filled with electrons as one moves across the periodic table. The S-block contains alkali and alkaline earth metals, the P-block includes non-metals and halogens, the D-block consists of transition metals, and the F-block includes lanthanides and actinides.

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2. Periodicity in Properties

The periodicity of elements refers to the recurring trends in the properties of elements as a result of their electron configurations. Some of the key periodic trends include:

1. Atomic Size (Radius):
   • Trend: Atomic size decreases across a period from left to right and increases down a group.
   • Explanation: As protons are added to the nucleus across a period, the nuclear charge increases, pulling electrons closer to the nucleus. As you move down a group, additional electron shells are added, increasing the distance between the nucleus and the outermost electron.
2. Ionization Energy:
   • Trend: Ionization energy increases across a period and decreases down a group.
   • Explanation: Ionization energy is the energy required to remove an electron from an atom. Across a period, the increasing nuclear charge holds the electrons more tightly, requiring more energy to remove them. Down a group, electrons are farther from the nucleus and are shielded by inner electrons, making them easier to remove.
3. Electronegativity:
   • Trend: Electronegativity increases across a period and decreases down a group.
   • Explanation: Electronegativity refers to the ability of an atom to attract electrons in a bond. Across a period, atoms have more protons, which enhances their ability to attract electrons. Down a group, the increased atomic size reduces the attraction between the nucleus and the bonding electrons.
4. Electron Affinity:
   • Trend: Electron affinity generally becomes more negative across a period and less negative down a group.
   • Explanation: Electron affinity is the energy change when an atom gains an electron. Across a period, atoms more readily accept electrons due to increased nuclear charge, while down a group, the larger atomic radius and electron shielding reduce the attraction for an incoming electron.
5. Metallic Character:
   • Trend: Metallic character decreases across a period and increases down a group.
   • Explanation: Metals are characterized by their ability to lose electrons easily. As you move across a period, elements become less metallic and more non-metallic. In contrast, down a group, elements exhibit stronger metallic characteristics due to the ease of electron loss.

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3. Applications of Periodicity in Properties

The understanding of the periodicity of elements has numerous practical applications in various fields, such as materials science, pharmaceuticals, environmental science, and industrial chemistry.

1. Materials Science:
   • Alloys: The periodic trends in atomic size and reactivity are crucial in alloy production. For instance, stainless steel is an alloy of iron, chromium, and nickel, where chromium’s high electronegativity contributes to corrosion resistance.
   • Semiconductors: Elements in the semiconductor industry often exploit the properties of metalloids such as silicon, which has periodic characteristics suitable for controlling electrical conductivity.
2. Pharmaceuticals:
   • The classification of elements and their periodic properties guide the development of drugs, especially metal-based drugs. For instance, cisplatin, a platinum-based anticancer drug, leverages the periodicity of platinum’s reactivity to bind to DNA in cancer cells.
3. Environmental Science:
   • Understanding the periodic behavior of elements is crucial for managing pollutants. For example, the periodic trends of heavy metals like mercury and lead help in studying their mobility and toxicity in the environment.
4. Industrial Chemistry:
   • The design of industrial catalysts often depends on periodic properties such as electronegativity and oxidation states. For example, vanadium and tungsten are often used in catalytic converters due to their stability and ability to facilitate oxidation reactions.

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4. Conclusion

The classification of elements and the periodicity of their properties are fundamental to understanding the chemical behavior of elements and their interactions. These principles provide insights into the physical and chemical properties of elements, which can be applied to a wide range of scientific and industrial fields. The periodic table not only organizes the elements in a way that reflects their atomic structure but also enables the prediction of their behavior in chemical reactions, helping scientists and engineers create new materials, develop new drugs, and better understand the natural world.

The study of periodic trends continues to be a vital area of research, providing a deeper understanding of the underlying principles of chemistry and physics. Its applications in technology, medicine, and environmental science demonstrate the importance of periodicity in shaping the modern world.

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References

Petrucci, R.H., et al. (2017). General Chemistry: Principles and Modern Applications (10th ed.). Pearson.

Zumdahl, S.S., & Zumdahl, S.A. (2013). Chemistry: An Atoms First Approach. Cengage Learning.

Chang, R. (2016). Chemistry: The Central Science (13th ed.). Pearson.

Industrial application of Classification of Elements and Periodicity in Properties ?

Industrial Applications of Classification of Elements and Periodicity in Properties

The classification of elements and the periodicity in their properties plays a vital role across a wide range of industrial applications. Understanding how elements behave based on their position in the periodic table and their periodic trends enables industries to select materials, design processes, and optimize performance. Below are some key industrial applications where these concepts are essential:

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1. Materials Science and Engineering

In materials science, the periodic trends in atomic size, ionization energy, electronegativity, and metallic character directly influence the development and selection of materials used in various industries.

• Alloy Production: The ability to predict the behavior of metals and non-metals based on their periodic properties is crucial for alloy development. For example, the strength, corrosion resistance, and ductility of alloys depend on the interaction of the elements involved, as seen in the production of stainless steel (iron + chromium + nickel). The periodicity of these elements helps engineers understand how they will behave together in different environments.
• Semiconductors: Elements such as silicon (Si) and germanium (Ge), which are metalloids, are vital in the semiconductor industry. The periodic properties of these elements, such as their ability to conduct electricity in specific conditions, are exploited in the design of integrated circuits, transistors, and solar panels. The behavior of elements in the periodic table allows engineers to modify conductivity by doping materials with other elements like phosphorus or boron.
• Corrosion Resistance: Metals like aluminum, zinc, and titanium are known for their resistance to corrosion due to their placement in the periodic table. The periodic properties of these metals, particularly their atomic size and electron configuration, are used to predict their reactivity and longevity in different environmental conditions.

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2. Catalysis and Chemical Engineering

In chemical engineering, periodicity plays a major role in designing catalysts for industrial reactions.

• Catalyst Design: Elements in the transition metal series (e.g., platinum, palladium, and nickel) are widely used as catalysts in various chemical processes. The periodicity of transition metals, such as their oxidation states and ability to facilitate electron transfer, makes them ideal for speeding up reactions without being consumed. For instance, platinum and palladium are used in catalytic converters to reduce harmful emissions from vehicles.
• Hydrogenation and Petrochemical Refining: The ability of certain transition metals to absorb and release hydrogen atoms makes them essential in processes like hydrogenation, which is used in the food industry to convert unsaturated fats into saturated oils, and in petrochemical refining to process crude oil into fuels and other chemicals.

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3. Environmental Applications

The periodic table and the periodic trends of elements are crucial for addressing environmental challenges such as waste management, pollution control, and sustainable energy production.

• Heavy Metal Removal: The properties of metals like lead, mercury, and cadmium, which are toxic in certain concentrations, can be understood and predicted through their periodic behavior. Understanding the ionization energies and solubility trends of these metals allows for the development of effective filtration, precipitation, and extraction methods for water purification and waste treatment.
• Water Treatment: Elements like chlorine and ozone, which are highly reactive and have strong oxidizing properties, are used in water disinfection. The periodicity in their electron configuration helps determine their reactivity, allowing for their efficient use in killing bacteria and pathogens in drinking water and wastewater.

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4. Pharmaceuticals and Healthcare

Periodic trends also play a key role in the design and use of pharmaceuticals, particularly in the development of metal-based drugs and in drug formulation.

• Metal-Based Drugs: Certain metals and metalloids, such as platinum (cisplatin) and gold (aurothiomalate), are used in the treatment of cancer and autoimmune diseases. The periodic properties of these elements, such as their ability to interact with biological molecules, form stable complexes, and affect cellular functions, are key to their therapeutic effects.
• Radiopharmaceuticals: Elements like iodine (I-131), used in cancer treatment, and technetium (Tc-99m), used in medical imaging, are essential in nuclear medicine. The periodic properties, particularly nuclear properties like half-life and radioactivity, guide the choice of isotopes for specific medical applications.

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5. Electronics and Energy Industries

The periodic properties of elements are crucial in the electronics and energy sectors, especially for the development of batteries, capacitors, and other energy storage devices.

• Battery Technology: Lithium (Li), a highly reactive metal found in the alkali metal group, is used extensively in rechargeable lithium-ion batteries. The low ionization energy and high reactivity of lithium, as described by its position in the periodic table, contribute to its effectiveness in energy storage and high charge density.
• Superconductivity: Certain elements, particularly in the lanthanide series, exhibit superconducting properties at low temperatures. The understanding of periodic trends allows for the development of materials with zero electrical resistance, which are used in high-efficiency power transmission, magnetic resonance imaging (MRI), and advanced particle accelerators.
• Solar Cells: The properties of semiconductors such as silicon, gallium arsenide, and cadmium telluride are utilized in photovoltaic cells. These elements’ ability to absorb and convert sunlight into electricity is based on their position in the periodic table and their unique electronic properties, which enable efficient solar energy conversion.

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6. Agriculture and Fertilizer Production

The classification and periodicity of elements are vital in agricultural chemistry for developing fertilizers and soil additives.

• Fertilizers: Elements like nitrogen, phosphorus, and potassium, found in large quantities in fertilizers, play essential roles in plant growth. The periodic properties of these elements, such as their ionization energies and reactivity, determine how they interact with soil and plants, affecting nutrient uptake and plant health.
• Soil Treatment: The periodic behavior of elements like calcium, magnesium, and sulfur is critical for soil treatment and pH regulation. These elements are used in agricultural lime and gypsum to adjust soil acidity and improve nutrient availability for crops.

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Conclusion

The classification of elements and periodicity in their properties are foundational concepts with wide-reaching industrial applications. From material selection and catalyst design to pharmaceuticals, energy solutions, and environmental protection, understanding the periodic trends allows industries to optimize processes, design better products, and develop new technologies. The industrial applications of these principles continue to grow as science and technology advance, reinforcing the importance of periodicity in the development of innovative and sustainable solutions across multiple sectors.

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References

1. Petrucci, R.H., et al. (2017). General Chemistry: Principles and Modern Applications (10th ed.). Pearson.
2. Zumdahl, S.S., & Zumdahl, S.A. (2013). Chemistry: An Atoms First Approach. Cengage Learning.
3. Chang, R. (2016). Chemistry: The Central Science (13th ed.). Pearson.

Research and development of Classification of Elements and Periodicity in Properties ?

The research and development (R&D) of Classification of Elements and Periodicity in Properties focuses on understanding and utilizing the periodic trends of elements to innovate and develop new materials, technologies, and processes across various scientific and industrial fields. Here’s an overview of R&D efforts in this area:

1. Development of New Materials

• Alloy Design: R&D in metallurgy relies heavily on periodic properties to develop new alloys with desired mechanical, thermal, and electrical properties. For example, understanding the trends in atomic size, ionization energy, and electronegativity across groups helps researchers design alloys with enhanced properties for aerospace, automotive, and construction industries.
• Superconducting Materials: Research is continuously being conducted to discover and synthesize new materials that exhibit superconductivity at higher temperatures. This involves understanding the periodic properties of elements like yttrium (Y), barium (Ba), and copper (Cu) in order to engineer new compounds for energy-efficient technologies like magnetic resonance imaging (MRI) and particle accelerators.
• Nanomaterials: The classification and periodic trends of elements at the nano scale are crucial in developing novel nanomaterials. Researchers are exploring the synthesis of carbon-based nanomaterials (e.g., carbon nanotubes) and metal nanoparticles, utilizing the unique properties of elements like carbon (C), gold (Au), and silver (Ag), which have distinct behaviors at the nanoscale compared to bulk materials.

2. Advances in Energy Technologies

• Solar Cells and Photovoltaic Materials: R&D in the development of efficient photovoltaic cells often involves understanding the periodic trends of elements such as silicon (Si), gallium (Ga), and arsenic (As). By manipulating the electronic properties of these elements, researchers aim to improve the efficiency of solar cells. Research is also focused on developing alternative materials, such as perovskite solar cells, which utilize the periodic properties of elements like lead (Pb) and tin (Sn).
• Energy Storage: The development of advanced battery technologies, such as lithium-ion and solid-state batteries, heavily depends on periodic trends. Lithium-based compounds, such as lithium cobalt oxide and lithium iron phosphate, are integral to modern batteries, and their properties—such as ion mobility and electrochemical stability—are optimized through R&D efforts.
• Nuclear Power: Research in nuclear energy relies on the periodic properties of elements like uranium (U) and thorium (Th). Understanding the nuclear properties, such as half-life and neutron absorption, allows for the development of more efficient nuclear fuel cycles and waste management solutions.

3. Chemical Engineering and Catalysis

• Catalyst Development: Transition metals like platinum (Pt), palladium (Pd), and rhodium (Rh) are essential in catalytic processes, such as hydrogenation, fuel production, and environmental cleanup. Research focuses on understanding their electron configurations, reactivity, and ability to facilitate chemical reactions. Researchers are working on improving catalyst efficiency and sustainability by exploring the periodic trends of these elements and their alloys or composites.
• Green Chemistry: The development of environmentally friendly chemical processes often involves using elements with specific periodic properties that promote more efficient and less toxic reactions. For example, R&D is focused on using iron (Fe), copper (Cu), and nickel (Ni) as more sustainable alternatives to precious metals in catalysis.

4. Quantum Materials and Technologies

• Quantum Computing: Elements from the periodic table play a key role in the development of quantum computing materials. Research focuses on the periodic trends of elements like silicon (Si), germanium (Ge), and indium (In) for use in quantum dots, transistors, and qubits, which are fundamental components of quantum computers. Understanding the electronic configurations and band gaps of these materials is essential for improving their performance in quantum systems.
• Topological Insulators: Topological insulators, materials that conduct electricity on their surface while insulating the interior, are an area of active R&D. These materials typically involve elements from group 15, such as bismuth (Bi), and group 16, such as selenium (Se). Understanding the periodic trends in electron behavior in these elements enables the development of materials with unique electronic properties that can be used in next-generation electronics.

5. Pharmaceutical and Medical Research

• Metal-Based Drugs: Research in medicinal chemistry has led to the development of metal-based drugs, including cisplatin, a chemotherapy drug that contains platinum, and other compounds containing gold (Au) and ruthenium (Ru). The periodic properties of these elements, such as their ability to form coordination complexes and their interaction with biological molecules, are key to their therapeutic effects.
• Diagnostic Imaging: Elements like technetium (Tc-99m) and gallium (Ga) are used in radiopharmaceuticals for imaging purposes. R&D in this field involves studying the periodic properties of isotopes, such as their half-life, radiation type, and decay modes, to optimize their effectiveness for specific medical applications, including cancer diagnostics and bone scans.

6. Environmental Sustainability

• Wastewater Treatment: R&D is focused on improving the efficiency of removing toxic metals from wastewater, such as lead (Pb) and mercury (Hg). The periodic classification of elements helps identify methods of treatment, including adsorption and precipitation, based on the chemical reactivity and solubility of these metals.
• Carbon Capture: Carbon capture and storage (CCS) technologies rely on materials that can efficiently absorb or react with carbon dioxide (CO₂). Research is exploring materials such as zeolites and metal-organic frameworks (MOFs), which are designed using elements from groups 2, 12, and 14. Understanding the periodic properties of these elements allows researchers to enhance their capacity for capturing and storing CO₂.

7. Food and Agricultural Sciences

• Fertilizers: Understanding the periodic trends of elements such as nitrogen (N), phosphorus (P), and potassium (K) helps researchers develop more efficient and environmentally friendly fertilizers. R&D focuses on optimizing the ionic forms and solubility of these elements to increase agricultural productivity while minimizing environmental impact.
• Pesticide Development: Research into pesticide development involves understanding the periodic properties of elements like arsenic (As), boron (B), and fluorine (F), which are used in the synthesis of toxic chemicals. Researchers aim to develop more effective and safer chemicals by exploiting the reactivity and stability of these elements.

8. Education and Computational Modeling

• Simulations and Predictive Models: R&D in computational chemistry and material science often involves creating predictive models based on the periodic properties of elements. Quantum mechanical simulations help researchers predict the behavior of atoms in various configurations, leading to the design of new materials or chemicals with desired properties.

Conclusion

Research and development in the area of classification of elements and periodicity in properties is foundational to many cutting-edge technologies. It spans multiple industries, from material science to quantum computing, pharmaceuticals to energy production. By understanding and exploiting the periodic trends and properties of elements, researchers are driving innovations that improve product performance, sustainability, and functionality across various domains. The continuous study of periodic trends not only aids in material and process optimization but also opens new avenues for technological advancements and industrial applications.

Courtesy : LearnoHub – Class 11, 12

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^ Jump up to:^a b Cao, Changsu; Vernon, René E.; Schwarz, W. H. Eugen; Li, Jun (6 January 2021). “Understanding Periodic and Non-periodic Chemistry in Periodic Tables”. Frontiers in Chemistry. 8 (813): 813. Bibcode:2021FrCh….8..813S. doi:10.3389/fchem.2020.00813. PMC 7818537. PMID 33490030.

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^ Wulfsberg, p. 27

^ Jump up to:^a b Petrucci et al., pp. 326–7

^ Farberovich, O. V.; Kurganskii, S. I.; Domashevskaya, E. P. (1980). “Problems of the OPW Method. II. Calculation of the Band Structure of ZnS and CdS”. Physica Status Solidi B. 97 (2): 631–640. Bibcode:1980PSSBR..97..631F. doi:10.1002/pssb.2220970230.

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^ Jump up to:^a b c Krinsky, Jamin L.; Minasian, Stefan G.; Arnold, John (8 December 2010). “Covalent Lanthanide Chemistry Near the Limit of Weak Bonding: Observation of (CpSiMe₃)₃Ce−ECp* and a Comprehensive Density Functional Theory Analysis of Cp₃Ln−ECp (E = Al, Ga)”. Inorganic Chemistry. 50 (1). American Chemical Society (ACS): 345–357. doi:10.1021/ic102028d. ISSN 0020-1669. PMID 21141834.

^ Jump up to:^a b c Jensen, W. B. (2015). “Some Comments on the Position of Lawrencium in the Periodic Table” (PDF). Archived from the original (PDF) on 23 December 2015. Retrieved 20 September 2015.

^ Wang, Fan; Le-Min, Li (2002). “镧系元素 4f 轨道在成键中的作用的理论研究” [Theoretical Study on the Role of Lanthanide 4f Orbitals in Bonding]. Acta Chimica Sinica (in Chinese). 62 (8): 1379–84.

^ Xu, Wei; Ji, Wen-Xin; Qiu, Yi-Xiang; Schwarz, W. H. Eugen; Wang, Shu-Guang (2013). “On structure and bonding of lanthanoid trifluorides LnF₃ (Ln = La to Lu)”. Physical Chemistry Chemical Physics. 2013 (15): 7839–47. Bibcode:2013PCCP…15.7839X. doi:10.1039/C3CP50717C. PMID 23598823.

^ Chi, Chaoxian; Pan, Sudip; Jin, Jiaye; Meng, Luyan; Luo, Mingbiao; Zhao, Lili; Zhou, Mingfei; Frenking, Gernot (2019). “Octacarbonyl Ion Complexes of Actinides [An(CO)8]+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding”. Chem. Eur. J. 25 (50): 11772–11784. doi:10.1002/chem.201902625. PMC 6772027. PMID 31276242.

^ Singh, Prabhakar P. (1994). “Relativistic effects in mercury: Atom, clusters, and bulk”. Physical Review B. 49 (7): 4954–4958. Bibcode:1994PhRvB..49.4954S. doi:10.1103/PhysRevB.49.4954. PMID 10011429.

^ Hu, Shu-Xian; Zou, Wenli (23 September 2021). “Stable copernicium hexafluoride (CnF₆) with an oxidation state of VI+”. Physical Chemistry Chemical Physics. 2022 (24): 321–325. Bibcode:2021PCCP…24..321H. doi:10.1039/D1CP04360A. PMID 34889909.

^ Seth, Michael; Schwerdtfeger, Peter; Fægri, Knut (1999). “The chemistry of superheavy elements. III. Theoretical studies on element 113 compounds”. Journal of Chemical Physics. 111 (14): 6422–6433. Bibcode:1999JChPh.111.6422S. doi:10.1063/1.480168. hdl:2292/5178. S2CID 41854842.

^ Kelley, Morgan P.; Deblonde, Gauthier J.-P.; Su, Jing; Booth, Corwin H.; Abergel, Rebecca J.; Batista, Enrique R.; Yang, Ping (2018). “Bond Covalency and Oxidation State of Actinide Ions Complexed with Therapeutic Chelating Agent 3,4,3-LI(1,2-HOPO)”. Inorganic Chemistry. 57 (9): 5352–5363. doi:10.1021/acs.inorgchem.8b00345. OSTI 1458511. PMID 29624372.

^ Johansson, B.; Abuja, R.; Eriksson, O.; et al. (1995). “Anomalous fcc crystal structure of thorium metal”. Physical Review Letters. 75 (2): 280–283. Bibcode:1995PhRvL..75..280J. doi:10.1103/PhysRevLett.75.280. PMID 10059654.

^ Jump up to:^a b Xu, Wen-Hua; Pyykkö, Pekka (8 June 2016). “Is the chemistry of lawrencium peculiar”. Phys. Chem. Chem. Phys. 2016 (18): 17351–5. Bibcode:2016PCCP…1817351X. doi:10.1039/c6cp02706g. hdl:10138/224395. PMID 27314425. S2CID 31224634. Retrieved 24 April 2017.

^ Jump up to:^a b c Scerri, p. 354–6

^ Oganessian, Yu.Ts.; Abdullin, F.Sh.; Bailey, P.D.; Benker, D.E.; Bennett, M.E.; Dmitriev, S.N.; et al. (2010). “Synthesis of a new element with atomic number Z = 117″. Physical Review Letters. 104 (14): 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935. S2CID 3263480.

^ Oganessian, Yu. T.; et al. (2002). “Results from the first ²⁴⁹
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^ Jump up to:^a b “IUPAC Announces the Names of the Elements 113, 115, 117, and 118”. IUPAC. 30 November 2016. Archived from the original on 30 November 2016. Retrieved 1 December 2016.

^ National Institute of Standards and Technology (NIST) (August 2019). “Periodic Table of the Elements”. NIST. Archived from the original on 8 February 2021. Retrieved 7 February 2021.

^ Fricke, B. (1975). Dunitz, J. D. (ed.). “Superheavy elements a prediction of their chemical and physical properties”. Structure and Bonding. 21. Berlin: Springer-Verlag: 89–144. doi:10.1007/BFb0116496. ISBN 978-3-540-07109-9.

^ Jump up to:^a b c Lemonick, Sam (2019). “The periodic table is an icon. But chemists still can’t agree on how to arrange it”. C&EN News. Archived from the original on 28 January 2021. Retrieved 16 December 2020.

^ Jump up to:^a b Gray, p. 12

^ Jump up to:^{a b c d e} Vlasov, L.; Trifonov, D. (1970). 107 Stories About Chemistry. Translated by Sobolev, D. Mir Publishers. pp. 23–27. ISBN 978-0-8285-5067-3.

^ Jump up to:^{a b c d e} Rayner-Canham, Geoffrey (2020). The Periodic Table: Past, Present, Future. World Scientific. pp. 53–70, 85–102. ISBN 978-981-12-1850-7.

^ Clayden, Jonathan; Greeves, Nick; Warren, Stuart; Wothers, Peter (2001). Organic Chemistry (1st ed.). Oxford University Press. ISBN 978-0-19-850346-0.

^ Seaborg, G. (1945). “The chemical and radioactive properties of the heavy elements”. Chemical & Engineering News. 23 (23): 2190–93. doi:10.1021/cen-v023n023.p2190.

^ Jump up to:^a b Kaesz, Herb; Atkins, Peter (2009). “A Central Position for Hydrogen in the Periodic Table”. Chemistry International. 25 (6): 14. doi:10.1515/ci.2003.25.6.14.

^ Jump up to:^a b Greenwood & Earnshaw, throughout the book

^ Scerri, Eric (2004). “The Placement of Hydrogen in the Periodic Table”. Chemistry International. 26 (3): 21–22. doi:10.1515/ci.2004.26.3.21. Retrieved 1 January 2023.

^ Jump up to:^a b Thyssen, Pieter; Ceulemans, Arnout (2017). Shattered Symmetry: Group Theory from the Eightfold Way to the Periodic Table. Oxford University Press. pp. 336, 360–381. ISBN 978-0-19-061139-2.

^ Kurushkin, Mikhail (2020). “Helium’s placement in the Periodic Table from a crystal structure viewpoint”. IUCrJ. 7 (4): 577–578. Bibcode:2020IUCrJ…7..577K. doi:10.1107/S2052252520007769. PMC 7340260. PMID 32695406. Archived from the original on 19 October 2021. Retrieved 19 June 2020.

^ Jump up to:^a b c d Scerri, pp. 392−401

^ Jump up to:^a b Grochala, Wojciech (1 November 2017). “On the position of helium and neon in the Periodic Table of Elements”. Foundations of Chemistry. 20 (2018): 191–207. doi:10.1007/s10698-017-9302-7.

^ Bent Weberg, Libby (18 January 2019). “”The” periodic table”. Chemical & Engineering News. 97 (3). Archived from the original on 1 February 2020. Retrieved 27 March 2020.

^ Grandinetti, Felice (23 April 2013). “Neon behind the signs”. Nature Chemistry. 5 (2013): 438. Bibcode:2013NatCh…5..438G. doi:10.1038/nchem.1631. PMID 23609097.

^ Jump up to:^{a b c d e f} Siekierski and Burgess, pp. 23–26

^ Siekierski and Burgess, p. 128

^ Lewars, Errol G. (5 December 2008). Modeling Marvels: Computational Anticipation of Novel Molecules. Springer Science & Business Media. pp. 69–71. ISBN 978-1-4020-6973-4. Archived from the original on 19 May 2016.

^ Jump up to:^a b Wulfsberg, p. 53: “As pointed out by W. B. Jensen, the metallurgical resemblance [to yttrium] is much stronger for lutetium than for lanthanum, so we have adopted the metallurgist’s convention of listing Lu (and by extension Lr) below Sc and Y. An important additional advantage of this is that the periodic table becomes more symmetrical, and it becomes easier to predict electron configurations. E. R. Scerri points out that recent determinations of the electron configurations of most of the f-block elements now are more compatible with this placement of Lu and Lr.”

^ Jump up to:^a b Kondō, Jun (January 1963). “Superconductivity in Transition Metals”. Progress of Theoretical Physics. 29 (1): 1–9. Bibcode:1963PThPh..29….1K. doi:10.1143/PTP.29.1.

^ Barber, Robert C.; Karol, Paul J; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). “Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)”. Pure Appl. Chem. 83 (7): 1485. doi:10.1351/PAC-REP-10-05-01.

^ Karol, Paul J.; Barber, Robert C.; Sherrill, Bradley M.; Vardaci, Emanuele; Yamazaki, Toshimitsu (22 December 2015). “Discovery of the elements with atomic numbers Z = 113, 115 and 117 (IUPAC Technical Report)”. Pure Appl. Chem. 88 (1–2): 139–153. doi:10.1515/pac-2015-0502.

^ Pyykkö, Pekka (2019). “An essay on periodic tables” (PDF). Pure and Applied Chemistry. 91 (12): 1959–1967. doi:10.1515/pac-2019-0801. S2CID 203944816. Retrieved 27 November 2022.

^ Jump up to:^{a b c d e} Smits, Odile R.; Düllmann, Christoph E.; Indelicato, Paul; Nazarewicz, Witold; Schwerdtfeger, Peter (2023). “The quest for superheavy elements and the limit of the periodic table”. Nature Reviews Physics. 6 (2): 86–98. doi:10.1038/s42254-023-00668-y. S2CID 266276980.

^ Leigh, G. Jeffrey (2009). “Periodic Tables and IUPAC”. Chemistry International. 31 (1): 4–6. doi:10.1515/ci.2009.31.1.4. Retrieved 8 January 2024.

^ Leigh, G. Jeffrey, ed. (1990). Nomenclature of inorganic chemistry : recommendations 1990. Blackwell Scientific Publications. p. 283. ISBN 0-632-02319-8.

^ Vernon, R (2021). “The location and composition of Group 3 of the periodic table”. Foundations of Chemistry. 23 (2): 155–197. doi:10.1007/s10698-020-09384-2. S2CID 254501533.

^ Cotton, SA; Raithby, BR; Shield, A (2022). “A comparison of the structural chemistry of scandium, yttrium, lanthanum and lutetium: A contribution to the group 3 debate” (PDF). Coordination Chemistry Reviews. 455: 214366. doi:10.1016/j.ccr.2021.214366. S2CID 245712597.

^ Lavelle, Laurence (2008). “Lanthanum (La) and Actinium (Ac) Should Remain in the d-block”. Journal of Chemical Education. 85 (11): 1482–1483. Bibcode:2008JChEd..85.1482L. doi:10.1021/ed085p1482.

^ Jump up to:^{a b c d e f g} Johnson, David (1984). The Periodic Law (PDF). The Royal Society of Chemistry. ISBN 0-85186-428-7.

^ Wittig, Jörg (1973). “The pressure variable in solid state physics: What about 4f-band superconductors?”. In H. J. Queisser (ed.). Festkörper Probleme: Plenary Lectures of the Divisions Semiconductor Physics, Surface Physics, Low Temperature Physics, High Polymers, Thermodynamics and Statistical Mechanics, of the German Physical Society, Münster, March 19–24, 1973. Advances in Solid State Physics. Vol. 13. Berlin, Heidelberg: Springer. pp. 375–396. doi:10.1007/BFb0108579. ISBN 978-3-528-08019-8.

^ Jump up to:^a b Wulfsberg, p. 26

^ Jump up to:^{a b c d e} Greenwood and Earnshaw, pp. 27–9

^ Messler, R. W. (2010). The essence of materials for engineers. Sudbury, MA: Jones & Bartlett Publishers. p. 32. ISBN 978-0-7637-7833-0.

^ Myers, R. (2003). The basics of chemistry. Westport, CT: Greenwood Publishing Group. pp. 61–67. ISBN 978-0-313-31664-7.

^ Chang, R. (2002). Chemistry (7 ed.). New York: McGraw-Hill. pp. 289–310, 340–42. ISBN 978-0-07-112072-2.

^ Haas, Arthur Erich (1884–1941) Uber die elektrodynamische Bedeutung des Planckschen Strahlungsgesetzes und uber eine neue Bestimmung des elektrischen Elementarquantums und der dimension des wasserstoffatoms. Sitzungsberichte der kaiserlichen Akademie der Wissenschaften in Wien. 2a, 119 pp 119–144 (1910). Haas AE. Die Entwicklungsgeschichte des Satzes von der Erhaltung der Kraft. Habilitation Thesis, Vienna, 1909. Hermann, A. Arthur Erich Haas, Der erste Quantenansatz für das Atom. Stuttgart, 1965 [contains a reprint]

^ Jump up to:^a b Clark, Jim (2012). “Atomic and Ionic Radius”. Chemguide. Archived from the original on 14 November 2020. Retrieved 30 March 2021.

^ Cao, Chang-Su; Hu, Han-Shi; Li, Jun; Schwarz, W. H. Eugen (2019). “Physical origin of chemical periodicities in the system of elements”. Pure and Applied Chemistry. 91 (12): 1969–1999. doi:10.1515/pac-2019-0901. S2CID 208868546.

^ Kaupp, Martin (1 December 2006). “The role of radial nodes of atomic orbitals for chemical bonding and the periodic table”. Journal of Computational Chemistry. 28 (1): 320–25. doi:10.1002/jcc.20522. PMID 17143872. S2CID 12677737.

^ Jump up to:^a b c d Scerri, pp. 407–420

^ Greenwood and Earnshaw, p. 29

^ Imyanitov, Naum S. (2018). “Is the periodic table appears doubled? Two variants of division of elements into two subsets. Internal and secondary periodicity”. Foundations of Chemistry. 21: 255–284. doi:10.1007/s10698-018-9321-z. S2CID 254514910.

^ Chistyakov, V. M. (1968). “Biron’s Secondary Periodicity of the Side d-subgroups of Mendeleev’s Short Table”. Journal of General Chemistry of the USSR. 38 (2): 213–214. Retrieved 6 January 2024.

^ P. Pyykkö; M. Atsumi (2009). “Molecular Single-Bond Covalent Radii for Elements 1-118”. Chemistry: A European Journal. 15 (1): 186–197. doi:10.1002/chem.200800987. PMID 19058281.

^ Jump up to:^a b Pyykkö, Pekka; Desclaux, Jean Paul (1979). “Relativity and the periodic system of elements”. Accounts of Chemical Research. 12 (8): 276. doi:10.1021/ar50140a002.

^ Norrby, Lars J. (1991). “Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks?”. Journal of Chemical Education. 68 (2): 110. Bibcode:1991JChEd..68..110N. doi:10.1021/ed068p110.

^ Jump up to:^{a b c d e f} Fricke, Burkhard; Waber, J. T. (1971). “Theoretical Predictions of the Chemistry of Superheavy Elements: Continuation of the Periodic Table up to Z=184” (PDF). Actinides Reviews. 1: 433–485. Retrieved 5 January 2024.

^ Schädel, M. (2003). The Chemistry of Superheavy Elements. Dordrecht: Kluwer Academic Publishers. p. 277. ISBN 978-1-4020-1250-1.

^ Yakushev, A.; Khuyagbaatar, J.; Düllmann, Ch. E.; Block, M.; Cantemir, R. A.; Cox, D. M.; Dietzel, D.; Giacoppo, F.; Hrabar, Y.; Iliaš, M.; Jäger, E.; Krier, J.; Krupp, D.; Kurz, N.; Lens, L.; Löchner, S.; Mokry, Ch.; Mošať, P.; Pershina, V.; Raeder, S.; Rudolph, D.; Runke, J.; Sarmiento, L. G.; Schausten, B.; Scherer, U.; Thörle-Pospiesch, P.; Trautmann, N.; Wegrzecki, M.; Wieczorek, P. (23 September 2024). “Manifestation of relativistic effects in the chemical properties of nihonium and moscovium revealed by gas chromatography studies”. Frontiers in Chemistry. 12. Bibcode:2024FrCh…1274820Y. doi:10.3389/fchem.2024.1474820. PMC 11464923. PMID 39391836.

^ Wulfsberg, pp. 33–34

^ Greenwood and Earnshaw, pp. 24–5

^ Jump up to:^a b Clark, Jim (2016). “Ionisation Energy”. Chemguide. Archived from the original on 22 April 2021. Retrieved 30 March 2021.

^ Jump up to:^a b Clark, Jim (2012). “Electron Affinity”. Chemguide. Archived from the original on 23 April 2021. Retrieved 30 March 2021.

^ Cárdenas, Carlos; Ayers, Paul; De Proft, Frank; Tozer, David J.; Geerlings, Paul (2010). “Should negative electron affinities be used for evaluating the chemical hardness?”. Physical Chemistry Chemical Physics. 13 (6): 2285–2293. doi:10.1039/C0CP01785J. PMID 21113528.

^ Schmidt, H. T.; Reinhed, P.; Orbán, A.; Rosén, S.; Thomas, R. D.; Johansson, H. A. B.; Werner, J.; Misra, D.; Björkhage, M.; Brännholm, L.; Löfgren, P.; Liljeby, L.; Cederquist, H. (2012). “The lifetime of the helium anion”. Journal of Physics: Conference Series. 388 (1): 012006. Bibcode:2012JPhCS.388a2006S. doi:10.1088/1742-6596/388/1/012006.

^ Wulfsberg, p. 28

^ Wulfsberg, p. 274

^ Greenwood and Earnshaw, p. 113

^ Jump up to:^a b c Siekierski and Burgess, pp. 45–54

^ Amador, J.; Puebla, E. Gutierrez; Monge, M. A.; Rasines, I.; Valero, C. Ruiz (1988). “Diantimony Tetraoxides Revisited”. Inorganic Chemistry. 27 (8): 1367–1370. doi:10.1021/ic00281a011.

^ Jump up to:^a b c Siekierski and Burgess, pp. 134–137

^ Jump up to:^a b Siekierski and Burgess, pp. 178–180

^ Jump up to:^a b Scerri, pp. 14–15

^ Jump up to:^a b c d Greenwood and Earnshaw, pp. 25–6

^ Allen, Leland C. (1989). “Electronegativity is the average one-electron energy of the valence-shell electrons in ground-state free atoms”. Journal of the American Chemical Society. 111 (25): 9003–9014. Bibcode:1989JAChS.111.9003A. doi:10.1021/ja00207a003.

^ Dieter, R. K.; Watson, R. T. (2009). “Transmetalation reactions producing organocopper compounds”. In Rappoport, Z.; Marek, I. (eds.). The Chemistry of Organocopper Compounds. Vol. 1. John Wiley & Sons. pp. 443–526. ISBN 978-0-470-77296-6. Archived from the original on 17 October 2022. Retrieved 6 April 2022.

^ Carrasco, Rigo A.; Zamarripa, Cesy M.; Zollner, Stefan; Menéndez, José; Chastang, Stephanie A.; Duan, Jinsong; Grzybowski, Gordon J.; Claflin, Bruce B.; Kiefer, Arnold M. (2018). “The direct bandgap of gray α-tin investigated by infrared ellipsometry”. Applied Physics Letters. 113 (23): 232104. Bibcode:2018ApPhL.113w2104C. doi:10.1063/1.5053884. S2CID 125130534.

^ “Intermolecular bonding – van der Waals forces”. Archived from the original on 22 January 2022. Retrieved 17 November 2021.

^ Clark, Jim (2019). “Metallic Bonding”. Chemguide. Archived from the original on 21 April 2021. Retrieved 30 March 2021.

^ Pastor, G. M.; Stampfli, P.; Bennemann, K. (1988). “On the transition from Van der Waals- to metallic bonding in Hg-clusters as a function of cluster size”. Physica Scripta. 38 (4): 623–626. Bibcode:1988PhyS…38..623P. doi:10.1088/0031-8949/38/4/022. S2CID 250842014.

^ Jump up to:^{a b c d e f g} Siekierski and Burgess, pp. 60–66

^ Jump up to:^a b c d Steudel, Ralf; Scheschkewitz, David (2020). Chemistry of the Non-Metals. Walter de Gruyter. pp. 154–155, 425, 436. ISBN 978-3-11-057805-8. In Group 15 of the Periodic Table, as in both neighboring groups, the metallic character increases when going down. More specifically, there is a transition from a purely non-metallic element (N) via elements with nonmetallic and metallic modifications to purely metallic elements (Sb, Bi). This chapter addresses the two elements besides nitrogen, which are clearly nonmetallic under standard conditions: phosphorus and arsenic. The chemistry of arsenic, however, is only briefly described as many of the arsenic compounds resemble the corresponding phosphorus species.

^ McMinis, J.; Clay, R.C.; Lee, D.; Morales, M.A. (2015). “Molecular to Atomic Phase Transition in Hydrogen under High Pressure”. Phys. Rev. Lett. 114 (10): 105305. Bibcode:2015PhRvL.114j5305M. doi:10.1103/PhysRevLett.114.105305. PMID 25815944.

^ Hawkes, Stephen J. (2001). “Semimetallicity?”. Journal of Chemical Education. 78 (12): 1686. Bibcode:2001JChEd..78.1686H. doi:10.1021/ed078p1686.

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^ Rayner-Canham, Geoff; Overton, Tina (2008). Descriptive Inorganic Chemistry (5th ed.). New York: W. H. Freeman and Company. p. 194. ISBN 978-1-4292-2434-5.

^ Jump up to:^a b Mewes, J.-M.; Smits, O. R.; Kresse, G.; Schwerdtfeger, P. (2019). “Copernicium is a Relativistic Noble Liquid”. Angewandte Chemie International Edition. 58 (50): 17964–17968. doi:10.1002/anie.201906966. PMC 6916354. PMID 31596013.

^ Jump up to:^a b Florez, Edison; Smits, Odile R.; Mewes, Jan-Michael; Jerabek, Paul; Schwerdtfeger, Peter (2022). “From the gas phase to the solid state: The chemical bonding in the superheavy element flerovium”. The Journal of Chemical Physics. 157 (6): 064304. Bibcode:2022JChPh.157f4304F. doi:10.1063/5.0097642. PMID 35963734. S2CID 250539378.

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^ Jump up to:^a b Ingo, Peter (15 September 2022). “Study shows flerovium is the most volatile metal in the periodic table”. phys.org. Retrieved 22 November 2022.

^ Jump up to:^a b Yakushev, A.; Lens, L.; Düllmann, Ch. E.; et al. (25 August 2022). “On the adsorption and reactivity of element 114, flerovium”. Frontiers in Chemistry. 10 (976635): 976635. Bibcode:2022FrCh…10.6635Y. doi:10.3389/fchem.2022.976635. PMC 9453156. PMID 36092655.

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^ Ball, Philip (13 September 2013). “Metallic properties predicted for astatine”. Chemistry World. Retrieved 7 April 2023.

^ Jump up to:^a b Clark, Jim (2012). “Metallic Structures”. Chemguide. Archived from the original on 24 April 2021. Retrieved 30 March 2021.

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^ Wiberg, Egon; Wiberg, Nils & Holleman, Arnold Frederick (2001). Inorganic chemistry. Academic Press. p. 758. ISBN 978-0-12-352651-9.

^ Hammond, C. R. (2004). The Elements, in Handbook of Chemistry and Physics (81st ed.). Boca Raton (FL, US): CRC press. pp. 4–1. ISBN 978-0-8493-0485-9.

^ G.V. Samsonov, ed. (1968). “Mechanical Properties of the Elements”. Handbook of the Physicochemical Properties of the Elements. New York, USA: IFI-Plenum. pp. 387–446. doi:10.1007/978-1-4684-6066-7_7. ISBN 978-1-4684-6066-7. Archived from the original on 2 April 2015.

^ Hammer, B.; Norskov, J. K. (1995). “Why gold is the noblest of all the metals”. Nature. 376 (6537): 238–240. Bibcode:1995Natur.376..238H. doi:10.1038/376238a0. S2CID 4334587.

^ Johnson, P. B.; Christy, R. W. (1972). “Optical Constants of the Noble Metals”. Physical Review B. 6 (12): 4370–4379. Bibcode:1972PhRvB…6.4370J. doi:10.1103/PhysRevB.6.4370.

^ Clark, Jim (2018). “Atomic and Physical Properties of the Period 3 Elements”. Chemguide. Archived from the original on 22 April 2021. Retrieved 30 March 2021.

^ Jump up to:^a b Clark, Jim (2015). “The Trend From Non-Metal to Metal In the Group 4 Elements”. Chemguide. Archived from the original on 27 April 2021. Retrieved 30 March 2021.

^ Wei, Lanhua; Kuo, P. K.; Thomas, R. L.; Anthony, T. R.; Banholzer, W. F. (1993). “Thermal conductivity of isotopically modified single crystal diamond”. Physical Review Letters. 70 (24): 3764–3767. Bibcode:1993PhRvL..70.3764W. doi:10.1103/PhysRevLett.70.3764. PMID 10053956.

^ Jump up to:^a b c d “Periodic Table of Chemical Elements”. www.acs.org. American Chemical Society. 2021. Archived from the original on 3 February 2021. Retrieved 27 March 2021.

^ “Periodic Table”. www.rsc.org. Royal Society of Chemistry. 2021. Archived from the original on 21 March 2021. Retrieved 27 March 2021.

^ Jump up to:^{a b c d e} Seaborg, G. (c. 2006). “transuranium element (chemical element)”. Encyclopædia Britannica. Archived from the original on 30 November 2010. Retrieved 16 March 2010.

^ Sherwin, E.; Weston, G. J. (1966). Spice, J. E. (ed.). Chemistry of the Non-Metallic Elements. Pergamon Press. ISBN 978-1-4831-3905-0.

^ Jump up to:^a b Hawkes, Stephen J. (2001). “Semimetallicity?”. Journal of Chemical Education. 78 (12): 1686–1687. Bibcode:2001JChEd..78.1686H. doi:10.1021/ed078p1686.

^ Jump up to:^a b Jensen, William B. (1986). “Classification, symmetry and the periodic table” (PDF). Comp. & Maths. With Appls. 12B (I/2). Archived (PDF) from the original on 31 January 2017. Retrieved 18 January 2017.

^ Greenwood and Earnshaw, pp. 29–31

^ Fernelius, W. C.; Loening, Kurt; Adams, Roy M. (1971). “Names of groups and elements”. Journal of Chemical Education. 48 (11): 730–731. Bibcode:1971JChEd..48..730F. doi:10.1021/ed048p730.

^ Jensen, William B. (2003). “The Place of Zinc, Cadmium, and Mercury in the Periodic Table” (PDF). Journal of Chemical Education. 80 (8): 952–961. Bibcode:2003JChEd..80..952J. doi:10.1021/ed080p952. Archived from the original (PDF) on 11 June 2010. Retrieved 6 May 2012.

^ Leigh, G. J., ed. (2011). Principles of Chemical Nomenclature (PDF). The Royal Society of Chemistry. p. 9. ISBN 978-1-84973-007-5.

^ Winter, Mark (1993–2022). “WebElements”. The University of Sheffield and WebElements Ltd, UK. Retrieved 5 December 2022.

^ Cowan, Robert D. (1981). The Theory of Atomic Structure and Spectra. University of California Press. p. 598. ISBN 978-0-520-90615-0.

^ Villar, G. E. (1966). “A suggested modification to the periodic chart”. Journal of Inorganic and Nuclear Chemistry. 28 (1): 25–29. doi:10.1016/0022-1902(66)80224-5.

^ Jump up to:^a b Cotton, S. A. (1996). “After the actinides, then what?”. Chemical Society Reviews. 25 (3): 219–227. doi:10.1039/CS9962500219.

^ Neve, Francesco (2022). “Chemistry of superheavy transition metals”. Journal of Coordination Chemistry. 75 (17–18): 2287–2307. doi:10.1080/00958972.2022.2084394. S2CID 254097024.

^ Mingos, Michael (1998). Essential Trends in Inorganic Chemistry. Oxford University Press. p. 387. ISBN 978-0-19-850109-1.

^ “A New Era of Discovery: the 2023 Long Range Plan for Nuclear Science” (PDF). U.S. Department of Energy. October 2023. Archived from the original (PDF) on 5 October 2023. Retrieved 20 October 2023 – via OSTI. Superheavy elements (Z > 102) are teetering at the limits of mass and charge.

^ Kragh, Helge (2017). “The search for superheavy elements: Historical and philosophical perspectives”. arXiv:1708.04064 [physics.hist-ph].

^ Theuns, Tom. “Metallicity of stars”. icc.dur.ac.uk. Durham University. Archived from the original on 27 September 2021. Retrieved 27 March 2021.

^ Burns, Gerald (1985). Solid State Physics. Academic Press, Inc. pp. 339–40. ISBN 978-0-12-146070-9.

^ Duffus, John H. (2002). “”Heavy Metals”–A Meaningless Term?” (PDF). Pure and Applied Chemistry. 74 (5): 793–807. doi:10.1351/pac200274050793. S2CID 46602106. Archived (PDF) from the original on 11 April 2021. Retrieved 27 March 2021.

^ Koppenol, W. (2016). “How to name new chemical elements” (PDF). Pure and Applied Chemistry. DeGruyter. doi:10.1515/pac-2015-0802. hdl:10045/55935. S2CID 102245448. Archived (PDF) from the original on 11 May 2020. Retrieved 15 August 2021.

^ Roth, Klaus (3 April 2018). “Is Element 118 a Noble Gas?”. Chemie in unserer Zeit. doi:10.1002/chemv.201800029. Archived from the original on 2 March 2021. Retrieved 27 March 2021.

^ The Chemical Society of Japan (25 January 2018). “【お知らせ】高等学校化学で用いる用語に関する提案（1）への反応”. www.chemistry.or.jp. The Chemical Society of Japan. Archived from the original on 16 May 2021. Retrieved 3 April 2021. 「12．アルカリ土類金属」の範囲についても，△を含めれば，すべての教科書で提案が考慮されている。歴史的には第4 周期のカルシウム以下を指していた用語だったが，「周期表の2 族に対応する用語とする」というIUPAC の勧告1）に従うのは現在では自然な流れだろう。

^ Wurzer, Ferdinand (1817). “Auszug eines Briefes vom Hofrath Wurzer, Prof. der Chemie zu Marburg” [Excerpt of a letter from Court Advisor Wurzer, Professor of Chemistry at Marburg]. Annalen der Physik (in German). 56 (7): 331–334. Bibcode:1817AnP….56..331.. doi:10.1002/andp.18170560709. Archived from the original on 8 October 2021. Retrieved 15 August 2021. Here, Döbereiner found that strontium’s properties were intermediate to those of calcium and barium.

^ Döbereiner, J. W. (1829). “Versuch zu einer Gruppirung der elementaren Stoffe nach ihrer Analogie” [An attempt to group elementary substances according to their analogies]. Annalen der Physik und Chemie. 2nd series (in German). 15 (2): 301–307. Bibcode:1829AnP….91..301D. doi:10.1002/andp.18290910217. Archived from the original on 8 October 2021. Retrieved 15 August 2021. For an English translation of this article, see: Johann Wolfgang Döbereiner: “An Attempt to Group Elementary Substances according to Their Analogies” (Lemoyne College (Syracuse, New York, USA)) Archived 9 March 2019 at the Wayback Machine

^ Horvitz, L. (2002). Eureka!: Scientific Breakthroughs That Changed The World. New York: John Wiley. p. 43. Bibcode:2001esbt.book…..H. ISBN 978-0-471-23341-1. OCLC 50766822.

^ Scerri, p. 47

^ Ball, P. (2002). The Ingredients: A Guided Tour of the Elements. Oxford: Oxford University Press. p. 100. ISBN 978-0-19-284100-1.

^ Jump up to:^a b Chisholm, Hugh, ed. (1911). “Newlands, John Alexander Reina” . Encyclopædia Britannica. Vol. 19 (11th ed.). Cambridge University Press. p. 515.

^ Meyer, Julius Lothar; Die modernen Theorien der Chemie (1864); table on page 137 Archived 2 January 2019 at the Wayback Machine

^ Scerri, pp. 106–108

^ Scerri, p. 113

^ Jump up to:^a b Scerri, pp. 117–123

^ Mendeleev, D. (1871). “The natural system of elements and its application to the indication of the properties of undiscovered elements”. Journal of the Russian Chemical Society (in Russian). 3: 25–56. Archived from the original on 13 August 2017. Retrieved 23 August 2017.

^ Scerri, p. 149

^ Scerri, p. 151–2

^ Rouvray, R. “Dmitri Mendeleev”. New Scientist. Archived from the original on 15 August 2021. Retrieved 19 April 2020.

^ Scerri, pp. 164–169

^ Jump up to:^a b c Marshall, J.L.; Marshall, V.R. (2010). “Rediscovery of the Elements: Moseley and Atomic Numbers” (PDF). The Hexagon. Vol. 101, no. 3. Alpha Chi Sigma. pp. 42–47. S2CID 94398490. Archived from the original (PDF) on 16 July 2019. Retrieved 15 August 2021.

^ A. van den Broek, Physikalische Zeitschrift, 14, (1913), 32–41

^ Scerri, p. 185

^ A. van den Broek, Die Radioelemente, das periodische System und die Konstitution der Atom, Physik. Zeitsch., 14, 32, (1913).

^ E. Rutherford, Phil. Mag., 27, 488–499 (Mar. 1914). “This has led to an interesting suggestion by van Broek that the number of units of charge on the nucleus, and consequently the number of external electrons, may be equal to the number of the elements when arranged in order of increasing atomic weight. On this view, the nucleus charges of hydrogen, helium, and carbon are 1, 2, 6 respectively, and so on for the other elements, provided there is no gap due to a missing element. This view has been taken by Bohr in his theory of the constitution of simple atoms and molecules.”

^ Atkins, P. W. (1995). The Periodic Kingdom. HarperCollins Publishers, Inc. p. 87. ISBN 978-0-465-07265-1.

^ Egdell, Russell G.; Bruton, Elizabeth (2020). “Henry Moseley, X-ray spectroscopy and the periodic table”. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 378 (2180). doi:10.1002/chem.202004775. PMID 32811359.

^ Hisamatsu, Yoji; Egashira, Kazuhiro; Maeno, Yoshiteru (2022). “Ogawa’s nipponium and its re-assignment to rhenium”. Foundations of Chemistry. 24: 15–57. doi:10.1007/s10698-021-09410-x.

^ Jump up to:^a b c Scerri, Eric (2013). A Tale of Seven Elements. Oxford University Press. pp. 47–53, 115. ISBN 978-0-19-539131-2.

^ See Bohr table from 1913 paper below.

^ Helge Kragh, Aarhus, Lars Vegard, Atomic Structure, and the Periodic System, Bull. Hist. Chem., VOLUME 37, Number 1 (2012), p.43.

^ Scerri, pp. 208–218

^ Niels Bohr, “On the Constitution of Atoms and Molecules, Part III, Systems containing several nuclei” Philosophical Magazine 26:857–875 (1913)

^ Kragh, Helge (1 January 1979). “Niels Bohr’s Second Atomic Theory”. Historical Studies in the Physical Sciences. 10: 123–186. doi:10.2307/27757389. ISSN 0073-2672. JSTOR 27757389.

^ W. Kossel, “Über Molekülbildung als Folge des Atom- baues”, Ann. Phys., 1916, 49, 229–362 (237).

^ Translated in Helge Kragh, Aarhus, Lars Vegard, Atomic Structure, and the Periodic System, Bull. Hist. Chem., VOLUME 37, Number 1 (2012), p.43.

^ Langmuir, Irving (June 1919). “The Arrangement of Electrons in Atoms and Molecules”. Journal of the American Chemical Society. 41 (6): 868–934. Bibcode:1919JAChS..41..868L. doi:10.1021/ja02227a002. ISSN 0002-7863. Archived from the original on 26 January 2021. Retrieved 22 October 2021.

^ Jump up to:^a b Bury, Charles R. (July 1921). “Langmuir’s Theory of the Arrangement of Electrons in Atoms and Molecules”. Journal of the American Chemical Society. 43 (7): 1602–1609. Bibcode:1921JAChS..43.1602B. doi:10.1021/ja01440a023. ISSN 0002-7863. Archived from the original on 30 October 2021. Retrieved 22 October 2021.

^ Jensen, William B. (2003). “The Place of Zinc, Cadmium, and Mercury in the Periodic Table” (PDF). Journal of Chemical Education. 80 (8): 952–961. Bibcode:2003JChEd..80..952J. doi:10.1021/ed080p952. Archived (PDF) from the original on 19 April 2012. Retrieved 18 September 2021. The first use of the term “transition” in its modern electronic sense appears to be due to the British chemist C. R.Bury, who first used the term in his 1921 paper on the electronic structure of atoms and the periodic table

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^ Burdette, Shawn C.; Thornton, Brett F. (2018). “Hafnium the lutécium I used to be”. Nature Chemistry. 10 (10): 1074. Bibcode:2018NatCh..10.1074B. doi:10.1038/s41557-018-0140-6. PMID 30237529. Retrieved 8 February 2024.

^ Scerri, pp. 218–23

^ Jensen, William B. (2007). “The Origin of the s, p, d, f Orbital Labels” (PDF). Journal of Chemical Education. 84 (5): 757–8. Bibcode:2007JChEd..84..757J. doi:10.1021/ed084p757. Archived from the original (PDF) on 23 November 2018. Retrieved 15 August 2021.

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^ Klechkovskii, V.M. (1962). “Justification of the Rule for Successive Filling of (n+l) Groups”. Journal of Experimental and Theoretical Physics. 14 (2): 334. Retrieved 23 June 2022.

^ Jump up to:^a b Demkov, Yury N.; Ostrovsky, Valentin N. (1972). “n+l Filling Rule in the Periodic System and Focusing Potentials”. Journal of Experimental and Theoretical Physics. 35 (1): 66–69. Bibcode:1972JETP…35…66D. Retrieved 25 November 2022.

^ Scerri, pp. 313–321

^ Scerri, pp. 322–340

^ Jump up to:^a b Seaborg, Glenn T. (1997). “Source of the Actinide Concept” (PDF). fas.org. Los Alamos National Laboratory. Archived (PDF) from the original on 15 August 2021. Retrieved 28 March 2021.

^ Scerri, pp. 356–9

^ Öhrström, Lars; Holden, Norman E. (2016). “The Three-letter Element Symbols”. Chemistry International. 38 (2): 4–8. doi:10.1515/ci-2016-0204. S2CID 124737708.

^ Wapstra, A. H. (1991). “Criteria that must be satisfied for the discovery of a new chemical element to be recognized”. Pure and Applied Chemistry. 63 (6): 879–886. doi:10.1351/pac199163060879. S2CID 95737691. Retrieved 18 October 2022.

^ “Names and symbols of transfermium elements (IUPAC Recommendations 1997)”. Pure and Applied Chemistry. 69 (12): 2471–2474. 1997. doi:10.1351/pac199769122471.

^ Hofmann, Sigurd (2019). “Criteria for New Element Discovery”. Chemistry International. 41 (1): 10–15. doi:10.1515/ci-2019-0103.

^ Scerri, E. (2012). “Mendeleev’s Periodic Table Is Finally Completed and What To Do about Group 3?”. Chemistry International. 34 (4). doi:10.1515/ci.2012.34.4.28. Archived from the original on 5 July 2017.

^ Scerri, pp. 356–363

^ Jump up to:^a b Chapman, Kit (30 November 2016). “What it takes to make a new element”. Chemistry World. Royal Society of Chemistry. Archived from the original on 28 October 2017. Retrieved 22 March 2022.

^ Briggs, Helen (29 January 2019). “150 years of the periodic table: Test your knowledge”. Archived from the original on 9 February 2019. Retrieved 8 February 2019.

^ Hofmann, Sigurd; Dmitriev, Sergey N.; Fahlander, Claes; Gates, Jacklyn M.; Roberto, James B.; Sakai, Hideyuki (4 August 2020). “On the discovery of new elements (IUPAC/IUPAP Report)”. Pure and Applied Chemistry. 92 (9): 1387–1446. doi:10.1515/pac-2020-2926. S2CID 225377737.

^ Jump up to:^a b Fricke, Burkhard (1975). “Superheavy elements: a prediction of their chemical and physical properties”. Recent Impact of Physics on Inorganic Chemistry. Structure and Bonding. 21: 89–144. doi:10.1007/BFb0116498. ISBN 978-3-540-07109-9. Retrieved 4 October 2013.

^ Jump up to:^a b c Fricke, Burkhard (1977). “Dirac–Fock–Slater calculations for the elements Z = 100, fermium, to Z = 173” (PDF). Recent Impact of Physics on Inorganic Chemistry. 19: 83–192. Bibcode:1977ADNDT..19…83F. doi:10.1016/0092-640X(77)90010-9. Retrieved 25 February 2016.

^ Jump up to:^a b Ball, P. (2019). “Extreme chemistry: experiments at the edge of the periodic table”. Nature. 565 (7741): 552–555. Bibcode:2019Natur.565..552B. doi:10.1038/d41586-019-00285-9. ISSN 1476-4687. PMID 30700884.

^ Dmitriev, Sergey; Itkis, Mikhail; Oganessian, Yuri (2016). Status and perspectives of the Dubna superheavy element factory (PDF). Nobel Symposium NS160 – Chemistry and Physics of Heavy and Superheavy Elements. doi:10.1051/epjconf/201613108001. Archived (PDF) from the original on 28 August 2021. Retrieved 15 August 2021.

^ Sokolova, Svetlana; Popeko, Andrei (24 May 2021). “How are new chemical elements born?”. jinr.ru. JINR. Archived from the original on 4 November 2021. Retrieved 4 November 2021.

^ Chapman, Kit (10 October 2023). “Berkeley Lab to lead US hunt for element 120 after breakdown of collaboration with Russia”. Chemistry World. Retrieved 20 October 2023.

^ Biron, Lauren (16 October 2023). “Berkeley Lab to Test New Approach to Making Superheavy Elements”. lbl.gov. Lawrence Berkeley National Laboratory. Retrieved 20 October 2023.

^ Gan, Z. G.; Huang, W. X.; Zhang, Z. Y.; Zhou, X. H.; Xu, H. S. (2022). “Results and perspectives for study of heavy and super-heavy nuclei and elements at IMP/CAS”. The European Physical Journal A. 58 (158). Bibcode:2022EPJA…58..158G. doi:10.1140/epja/s10050-022-00811-w.

^ Jump up to:^a b Scerri, Eric (2020). “Recent attempts to change the periodic table”. Philosophical Transactions of the Royal Society A. 378 (2180). Bibcode:2020RSPTA.37890300S. doi:10.1098/rsta.2019.0300. PMID 32811365. S2CID 221136189.

^ Frazier, K. (1978). “Superheavy Elements”. Science News. 113 (15): 236–38. doi:10.2307/3963006. JSTOR 3963006.

^ Jump up to:^a b c Fricke, B.; Greiner, W.; Waber, J. T. (1971). “The continuation of the periodic table up to Z = 172. The chemistry of superheavy elements”. Theoretica Chimica Acta. 21 (3): 235–60. doi:10.1007/BF01172015. S2CID 117157377.

^ Jump up to:^a b Pyykkö, P. (2011). “A suggested periodic table up to Z ≤ 172, based on Dirac–Fock calculations on atoms and ions”. Physical Chemistry Chemical Physics. 13 (1): 161–68. Bibcode:2011PCCP…13..161P. doi:10.1039/c0cp01575j. PMID 20967377. S2CID 31590563.

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