Question

Select the correct electron configuration for Cr. Question 2 options: 1 s 2 2 s 2 3 s 2 3 p 6 4 s 2 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 1 3 d 5 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 4 p 4

Answer 1

The electron configuration for Chromium (Cr) is [Ar]3d54s1 due to the stability of a half-filled d sub-level.

Step-by-step explanation:

The correct electron configuration for Chromium (Cr) can be a bit tricky due to an exception in the filling order of electron orbitals. Normally, we would expect Cr to have an electron configuration that ends with 4s23d4, but Cr is an exception to the general rule. Instead, its electrons are arranged to achieve a more stable, half-filled d orbital, giving it a unique electron configuration.

The correct electron configuration for Cr is [Ar]3d54s1. This is because having a half-filled d sublevel is particularly stable which results in Chromium promoting an electron from the 4s orbital to the 3d orbital, hence the configuration of 3d54s1 instead of 3d44s2.