Explain why transition elements with electronic configuration 3d44s2 a

1.	Explain why transition elements with electronic configuration 3d44s2 and 3d94s2 do not exist.
Answer» (1) d-orbitals are degenerate orbitals and they acquire extra stability when half-filled (3d⁵) or completely filled (3d¹⁰). Hence, 3d⁴ and 3d⁹ electronic configurations are less stable. (2) The energy difference between 3d and 4s subshells is very low, hence there arises a transfer of one electron from 45 orbital to 3d orbital. The electronic configuration changes as, 3d⁴, 4s² → 3d⁵4s¹ 3d⁹,4s² → 3d¹⁰ 4s¹ Therefore transition elements, with electronic configurations 3d⁴, 4s² and 3d⁹, 4s² do not exist.

Explain why transition elements with electronic configuration 3d44s2 and 3d94s2 do not exist.

Answer»

(1) d-orbitals are degenerate orbitals and they acquire extra stability when half-filled (3d⁵) or completely filled (3d¹⁰).

Hence,

3d⁴ and 3d⁹ electronic configurations are less stable.

(2) The energy difference between 3d and 4s subshells is very low, hence there arises a transfer of one electron from 45 orbital to 3d orbital.

The electronic configuration changes as,

3d⁴, 4s² → 3d⁵4s¹

3d⁹,4s² → 3d¹⁰ 4s¹

Therefore transition elements, with electronic configurations 3d⁴, 4s² and 3d⁹, 4s² do not exist.