Question

The electron configuration of a ground-state Co atom is:
which one is correct :

1-[Ar]4s23d7

2-1s22s22p63s23d9

3-[Ne]3s23d7

4-[Ar]4s13d5

5-[Ar]4s24d7

Answer 1

Answer:

5 Option is correct

Explanation:

Hope it helps You

Answer 2

Co (Cobalt) belongs to the third period of the periodic table the Noble gas present in the third period is argon so in order to save time we usually write electronic configuration wrt the Noble gas present in that period

You need to know the atomic no's of all the Noble gas elements so that the question becomes easier

Atomic no of argon is 18

Atomic no of Co is 27

Hence u need 9 more electrons

You also need to know that while filling electrons 4s2 is filled first then3d

Hence the answer is

(Ar)4s2 3d7

I hope it helps

I THINK I WROTE TOOOO MUCH