d orbital vs s orbital... a small chemistry question

[albertlee]

For the transition metal element Cr

 

why are there 5 electrons filling the 3d orbital and only 1 electron filling the 4s orbital?

 

I initially think that there should be 4e in 3d and 2e in 4s

 

Why is my way of electron configuration less stable than the one in the question?

 

 

please help

 

thanks

[insane_alien]

half filled orbitals are more stable than 4s2 and 3d4

 

a half filled orbital is still reactive unlike a fully filled orbital but it is preferrable over the other options available.

 

to have 2 electrons in the 4s2 but only 4 in the 3d orbital is at a higher energy, things like low energies.