Question

Gadolinium belongs to 4f series. It's atomic number is 64.
Which of the following is the correct electronic configuration
of gadolinium ? [2015 RS]
(a) [Xe]4f⁸6d² (b) [Xe]4f⁹5s¹
(c) [Xe] 4f⁷5d¹6s² (d) [Xe] 4f⁶5d²6s²

Answer 1

Answer:

The correct option is (c) [Xe] 4f⁷5d¹6s²

Answer 2

The electronic configuration of Gadolinium is (c) [Xe] 4f⁷5d¹6s².

• Xenon (Xe) has an atomic number and electron count of 54. Therefore, [Xe] represents a total of 54 electrons.

• Now, the number of electrons left to be arranged in Gadolinium = 64 - 54 = 10

• Electrons arrange themselves in a way that gains them maximum stability. Half-filled and completely filled orbitals are more stable than randomly filled orbitals.

• The f-orbital can accommodate a maximum of 14 electrons. Therefore, a presence of 7 electrons in the f-orbital makes it half-filled and quite stable.

• The s-orbital can accommodate a maximum of 2 electrons.

• Therefore, the remaining 10 electrons arrange themselves in the configuration 4f⁷5d¹6s², in order to gain stability.

• So, the electronic configuration of  Gadolinium (64) is [Xe] 4f⁷5d¹6s².