Question

The electronic configuration of gadolinium (Atomic number 64) is ______.

विकल्प

• `[Xe] 4f^3 5d^5 6s^2`

• `[Xe] 4f^7 5d^2 6s^1`

• `[Xe] 4f^7 5d^1 6s^2`

• `[Xe] 4f^8 5d^6 6s^2`

Answer 1

The electronic configuration of gadolinium (Atomic number 64) is `[Xe] 4f^7 5d^1 6s^2`.

Explanation:

The electronic configuration of La (Z = 57) is [Xe] 5d¹ 6s². Therefore, further addition of electrons occurs in the lower energy 4f-orbital till it is exactly half-filled at Eu (Z = 63) Thus, the electronic configuration of Eu is [Xe] 4f⁷ 6s². Thereafter, addition of next electron does not occur in the more stable exactly half-filled 4f⁷ shell but occurs in the little higher energy 5d-orbital. Thus, the electronic configuration of Gd (Z = 64) is [Xe] 4f⁷ 5d¹ 6s².