Question

1. What is the ground state electron configuration of Rubidium ( Rb ) ?

a) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ c) 5s¹

b) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶ 4d¹⁰ 5s¹   d)    1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4p⁶ 5s² 5p²

Answer 1

Rubidium electronic number= 37, It belongs to the first group (alkali metal) of the periodic table.

Rb electronic configuration= 1s2,2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 (option A)

option b should not be correct because here 3d orbital is not shown and 4d is filled before 5s.

option c is incomplete

option d should not be correct because here 4s is not filled and last electron enters in 5p.