Question

How is the electron configuration of chromium different?

Answer 1

The electron configuration of chromium is different because it contains five 3d electrons and one 4s electron, rather than four 3d electrons and two 4s electrons.

Explanation:

Electron configurations are determined experimentally. The electron configuration for chromium is `"[Ar]3d"^5"4s"^1"`. The difference between chromium's electron configuration and most other elements, is that the 3d sublevel and the 4s sublevel are half filled. It is expected that the 3d sublevel would contain 4 electrons, and that the 4s sublevel would contain 2 electrons. However, in the case of chromium, the half-filled 3d and 3s sublevels make the atoms of chromium more stable.

There are many transition metals that have unpredicted electron configurations, determined experimentally.

You can print a periodic table that has the electron configurations of the elements from here: https://www.vertex42.com/ExcelTemplates/periodic-table-of-elements.html