why do this happend ??(electronic configuration)?

Question

Cr: [Ar]4s^2 3d^4 = [Ar]4s^1 3d^5 ?????????

Answer 1

the 4s^1 3d^5 configuration is more stable than the 4s^2 3d^4 this is also true in the case of 4s^1 3d^10 which is more stable than 4s^2 3d^9. given the option the atom in question will always seek to be in a more stable electron configuration even if this means moving one of its electrons into a higher energy level.

Answer 2

Half filled,completely filled and empty atomic orbitals of the atoms are highly stable.So 3d orbital of Cr becomes more stable by getting 5 electrons in it as its capacity is of maximum 10 electrons.

Answer 3

Chromium has 5 3d orbitals. If each is half-full, it is in a lower energy state than having the 4s orbital full and one of the 3d orbitals empty.