Question

Which of the following elements involve gradual filling of 5f-level?

Options

• Lanthanoids

• Actinoids

• Transition metals

• Coinage metals

Answer 1

Actinoids

Explanation:

Actinoids are the 14 elements from thorium (Th, Z = 90) to lawrencium (Lr, Z = 103). These elements involve the gradual filling of 5f orbitals in their electronic configurations. That is why they are also known as 5f-block elements. In contrast, lanthanoids involve filling of 4f orbitals. Actinoids are typically radioactive and show variable oxidation states.