The electron configurations for vanadium is: $\ce{1s^2 2s^2 2p^2 3s^2 3p^6 3d^3 4s^2}$, and the electron configuration for chromium is: $\ce{1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^1}$.
In looking at the electron configurations of two consecutive elements, I noticed that an electron in the $\ce{4s}$ orbital "jumped" to the higher energy $\ce{3d}$ orbital. Why is this so?
