Question

Which of the following electron configurations is the most stable?

A. 1s^2 2s^2 2p^6 3s^2 3p^5

B. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^5

C. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2

D. 1s^2 2s^2 2p^6 3s^2 3p^6

E. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10

Answer 1

Can anybody explain?

Answer 2

I will put my money on D. Since it has a noble gas configuration, fully filled outer shell. B and E are transition metals. C is probably calcium (if atom). A is probably chlorine, but it's a halogen for sure.

Answer 3

Thanks a lot!!!