Why in transmission elements elecrons in presiding shell increase rather than that of last shell?

Asked by RAHUL rd | 2nd Mar, 2015, 09:43: AM

Expert Answer:

Electrons fill low energy orbitals (closer to the nucleus) before they fill higher energy ones. In case of transition elements 3d, 4s and 4p orbitals have almost same energy with the increasing order as given below:
4p > 3d > 4s
so the 4s orbital will fill first, followed by all the 3d orbitals and then the 4p orbitals.

Answered by Arvind Diwale | 2nd Mar, 2015, 11:19: AM