Question

Which of the following electron configurations is correct for nickel?

Select one:
a. [Ar] 4s2 3d8
b. [Kr] 4s1 3d8
c.

[Kr] 4s2 3d8
d. [Ar] 4s1 3d8

Answer 1

Answer:

Electron configuration of Ni ….

1s2, 2s2 2p6, 3s2 3p6 3d8, 4s2 …. or …. [Ar] 3d8, 4s2

You will notice that some answers have …4s2, 3d8 and some have 3d8, 4s2. The latter is correct. Despite what you may have read or heard, the 3d sublevel is not higher in energy than the 4s. The 4th energy level is always higher in energy than the 3d. The confusing comes from trying to extrapolate the electron configurations for K and Ca into the transition metals. As Z increases from 21 onward, the d-sublevel drops below the energy of the 4s, making the 4s sublevel the last one occupied and the first one emptied (for the first-row transition metals).

This is explained in the article in JCE by Eugen Schwarz (April 2010). The accompanying article has the graph showing the “collapse” of the d-orbitals.

Answer 2

electron configurations is correct for nickel is

1s2, 2s2 2p6, 3s2 3p6 3d8, 4s2 …. or …. [Ar] 3d8, 4s2

option a is correct

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