Why chromium has electron configuration 4s1 3d5?

Chromium has electron configuration of 4s1 3d5? Why

Chromium has  the expected electronic configuration is 4s2 3d4. But actually one electron from 4s gets transferred to 3d making it 4s1 3d5. This happens so because it is a more stable configuration.

In other words:
Electron orbitals are most stable when they are fully filled or half filled. … In the case of Chromium, after the 4s2 3d4 configuration is attained, an electron from the 4s orbital jumps to 3d subshell because 3d5 is a much more stable configuration than 3d4. That’s why final configuration for Chromium is 4s1 3d5.

Actually the order of stability of orbitals goes like this:

Fully filled > half filled > incompletely filled

  • s orbital can accommodate a maximum of 2 electrons
  • p orbital can accommodate a maximum of 6 electrons
  • d orbital can accomodate a maximum of 10 electrons f orbital can accomodate a maximum of 14 electrons

4s1 3d5 satisfies the condition that half filled orbital is more stable.

In case of vanadium the electronic configuration remains 4s1 3d3