Question

Which among the following lanthanoids, shows only +3 oxidation state?

Options

• Cerium

• Gadolinium

• Terbium

• Neodynium

Answer 1

Gadolinium

Explanation:

Gadolinium (Gd) has only one oxidation state, which is +3, and has the electronic structure [Xe] 4f⁷, 5d¹, 6S². To produce a stable +3 oxidation state, this element can easily give up three valence electrons from the 5d and 6s subshells. Because Gd contains half-filled (4f⁷) f-subshells, the state is exceptionally stable.