The electronic configuration of chromium is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 1 3 d 5 .
In the case of Chromium, after the 4s2 3d4 configuration is attained, an electron from the 4s orbitaljumps to the 3d subshell because 3d5 is a much more stable configuration than 3d4.
That's why thefinal configuration for Chromium is 4s1 3d5.
3d5 4s1 has a half-filled 'd' subshell and 's' subshell so this electronic configuration is more stable.
