The f- and d- block elements: Atomic size and its significance

  • The f-block and d-block elements are two sets of transition metals found in the periodic table.
  • They occupy the middle part of the periodic table.
  • The atomic size of these elements has important implications for their chemical behavior.
  • In this lecture, we will explore the atomic size of f-block and d-block elements and discuss its significance.
  • Atomic size refers to the size of an atom, which can be measured by its atomic radius.
  • Atomic radius is defined as the distance between the nucleus of an atom and its outermost electron shell.
  • Atomic size generally decreases across a period and increases down a group in the periodic table.
  • This trend is observed for both f-block and d-block elements.
  • The atomic size of f-block and d-block elements is influenced by their electron configurations.

Factors influencing atomic size

  • The atomic size of f-block and d-block elements is affected by the shielding effect and effective nuclear charge.
  • The shielding effect is the repulsion between electrons in different energy levels that shield the outermost electrons from the full effect of the nucleus.
  • Effective nuclear charge is the net positive charge experienced by the outermost electrons due to the attraction of the nucleus.
  • The stronger the shielding effect and the weaker the effective nuclear charge, the larger the atomic size.

Atomic size of f-block elements

  • F-block elements, also known as inner transition metals, are located at the bottom of the periodic table.
  • They have their outermost electrons in the f-orbital.
  • Due to the presence of f-orbitals, the atomic size of f-block elements is significantly larger than the d-block elements.
  • For example, the atomic size of lanthanides (f-block elements) is larger than that of transition metals (d-block elements) in the same period.

Atomic size of d-block elements

  • D-block elements, also known as transition metals, are located in the middle of the periodic table.
  • They have their outermost electrons in the d-orbital.
  • The atomic size of d-block elements is smaller compared to f-block elements.
  • This is because the d-orbital is closer to the nucleus, leading to a stronger effective nuclear charge and smaller atomic size.
  • Across a period in the periodic table, the atomic size of both f-block and d-block elements generally decreases.
  • This is due to the increase in effective nuclear charge, which attracts the outermost electrons closer to the nucleus.
  • For example, the atomic size of lanthanum (f-block element) is smaller than that of scandium (d-block element) in the same period.
  • Down a group in the periodic table, the atomic size of both f-block and d-block elements generally increases.
  • This is because the addition of a new energy level results in more shielding effect and weaker effective nuclear charge.
  • For example, the atomic size of cerium (f-block element) is larger than that of titanium (d-block element) in the same group.

Significance of atomic size

  • The atomic size of f-block and d-block elements impacts their physical and chemical properties.
  • Larger atomic sizes of f-block elements result in higher metallic character and lower ionization energies.
  • Smaller atomic sizes of d-block elements contribute to their high melting and boiling points and ability to form complex compounds.
  • Understanding atomic size trends is essential for predicting the behavior and reactivity of f-block and d-block elements.
  1. Factors influencing atomic size in f-block elements:
  • The atomic size of f-block elements is larger due to the presence of f-orbitals.
  • The shielding effect in f-block elements is stronger, resulting in larger atomic sizes.
  • The effective nuclear charge experienced by the outermost electrons is weaker in f-block elements, contributing to their larger atomic sizes.
  • Example: Comparing the atomic sizes of lanthanides (f-block elements) and transition metals (d-block elements) in the same period.
  1. Factors influencing atomic size in d-block elements:
  • The atomic size of d-block elements is smaller compared to f-block elements.
  • The d-orbital being closer to the nucleus leads to a stronger effective nuclear charge and smaller atomic size.
  • The shielding effect in d-block elements is less significant, contributing to their smaller atomic sizes.
  • Example: Comparing the atomic sizes of transition metals (d-block elements) in different periods.
  1. Periodic trend: Atomic size across a period:
  • Across a period, the atomic size of both f-block and d-block elements generally decreases.
  • This is due to the increase in effective nuclear charge, resulting in the attraction of outermost electrons closer to the nucleus.
  • Example: Comparing the atomic sizes of lanthanum (f-block element) and scandium (d-block element) in the same period.
  1. Periodic trend: Atomic size down a group:
  • Down a group, the atomic size of both f-block and d-block elements generally increases.
  • The addition of new energy levels increases the shielding effect and weakens the effective nuclear charge.
  • Example: Comparing the atomic sizes of cerium (f-block element) and titanium (d-block element) in the same group.
  1. Significance of large atomic size in f-block elements:
  • Larger atomic sizes contribute to higher metallic character in f-block elements.
  • The lower ionization energies in f-block elements make them more reactive.
  • Example: Lanthanides, with their large atomic sizes, are used in the production of alloys and catalysts.
  1. Significance of small atomic size in d-block elements:
  • The small atomic sizes of d-block elements contribute to their high melting and boiling points.
  • D-block elements can form complex compounds due to their smaller atomic sizes.
  • Example: Transition metals like iron and copper form coordination compounds with ligands.
  1. Importance of atomic size in predicting chemical behavior:
  • Understanding atomic size trends is crucial for predicting the behavior of f-block and d-block elements.
  • Atomic size influences the ability of elements to form bonds and compounds.
  • Example: The small atomic size of transition metals allows them to form stable complexes with ligands.
  1. Relationship between atomic size and reactivity:
  • Elements with large atomic sizes tend to be more reactive as they have lower ionization energies.
  • Elements with small atomic sizes may exhibit higher reactivity due to their ability to form stable complexes.
  • Example: Lanthanides have large atomic sizes and are highly reactive in various chemical reactions.
  1. Applications of atomic size trends:
  • Knowledge of atomic size trends is utilized in materials science and various industries.
  • The properties and behavior of f-block and d-block elements are essential for developing new materials and chemicals.
  • Example: Using atomic size trends to design catalysts for specific chemical reactions.
  1. Summary:
  • Atomic size is influenced by factors such as shielding effect and effective nuclear charge.
  • F-block elements have larger atomic sizes compared to d-block elements due to the presence of f-orbitals.
  • Atomic size generally decreases across a period and increases down a group in the periodic table.
  • Understanding atomic size trends is crucial for predicting the reactivity and behavior of f-block and d-block elements.
  1. Factors influencing atomic size in f-block elements:
  • The atomic size of f-block elements is larger due to the presence of f-orbitals.
  • The shielding effect in f-block elements is stronger, resulting in larger atomic sizes.
  • The effective nuclear charge experienced by the outermost electrons is weaker in f-block elements, contributing to their larger atomic sizes.
  • Example: Comparing the atomic sizes of lanthanides (f-block elements) and transition metals (d-block elements) in the same period.
  1. Factors influencing atomic size in d-block elements:
  • The atomic size of d-block elements is smaller compared to f-block elements.
  • The d-orbital being closer to the nucleus leads to a stronger effective nuclear charge and smaller atomic size.
  • The shielding effect in d-block elements is less significant, contributing to their smaller atomic sizes.
  • Example: Comparing the atomic sizes of transition metals (d-block elements) in different periods.
  1. Periodic trend: Atomic size across a period:
  • Across a period, the atomic size of both f-block and d-block elements generally decreases.
  • This is due to the increase in effective nuclear charge, resulting in the attraction of outermost electrons closer to the nucleus.
  • Example: Comparing the atomic sizes of lanthanum (f-block element) and scandium (d-block element) in the same period.
  1. Periodic trend: Atomic size down a group:
  • Down a group, the atomic size of both f-block and d-block elements generally increases.
  • The addition of new energy levels increases the shielding effect and weakens the effective nuclear charge.
  • Example: Comparing the atomic sizes of cerium (f-block element) and titanium (d-block element) in the same group.
  1. Significance of large atomic size in f-block elements:
  • Larger atomic sizes contribute to higher metallic character in f-block elements.
  • The lower ionization energies in f-block elements make them more reactive.
  • Example: Lanthanides, with their large atomic sizes, are used in the production of alloys and catalysts.
  1. Significance of small atomic size in d-block elements:
  • The small atomic sizes of d-block elements contribute to their high melting and boiling points.
  • D-block elements can form complex compounds due to their smaller atomic sizes.
  • Example: Transition metals like iron and copper form coordination compounds with ligands.
  1. Importance of atomic size in predicting chemical behavior:
  • Understanding atomic size trends is crucial for predicting the behavior of f-block and d-block elements.
  • Atomic size influences the ability of elements to form bonds and compounds.
  • Example: The small atomic size of transition metals allows them to form stable complexes with ligands.
  1. Relationship between atomic size and reactivity:
  • Elements with large atomic sizes tend to be more reactive as they have lower ionization energies.
  • Elements with small atomic sizes may exhibit higher reactivity due to their ability to form stable complexes.
  • Example: Lanthanides have large atomic sizes and are highly reactive in various chemical reactions.
  1. Applications of atomic size trends:
  • Knowledge of atomic size trends is utilized in materials science and various industries.
  • The properties and behavior of f-block and d-block elements are essential for developing new materials and chemicals.
  • Example: Using atomic size trends to design catalysts for specific chemical reactions.
  1. Summary:
  • Atomic size is influenced by factors such as shielding effect and effective nuclear charge.
  • F-block elements have larger atomic sizes compared to d-block elements due to the presence of f-orbitals.
  • Atomic size generally decreases across a period and increases down a group in the periodic table.
  • Understanding atomic size trends is crucial for predicting the reactivity and behavior of f-block and d-block elements.