# How is the electron configuration of chromium different?

May 13, 2017

Electron configurations are determined experimentally. The electron configuration for chromium is $\text{[Ar]3d"^5"4s"^1}$. 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.