Question

The most common oxidation state of lanthanoid elements is +3. Which of the following is likely to deviate easily from +3 oxidation state?

Options

• Ce (At. no. 58)

• La (At. no. 51)

• Lu (At. no. 71)

• Gd (At. no. 64)

Answer 1

Ce (At. no. 58)

Explanation:

The most common oxidation state of lanthanoids is +3. However, cerium (Ce) can easily deviate from +3 and show a +4 oxidation state. Cerium \[\ce{(Ce^{3+} -> Ce^{4+})}\] is stable because the Ce⁴⁺ ion has an empty 4f orbital (4f⁰), which is a stable electronic configuration. Therefore, cerium readily shows +4 oxidation state in addition to +3.