The possible subshells in n=3 energy shell are :
The subshell 4s has the smaller energy than the subshell 3d.But the subshell configuration of Cr is 1s2 2s2 2p6 3s2 3p6 3d5 4s1.why did 3d came 1st and 4s after it ???
The order of screeening effect of electorns of s, p, d and f orbitals fo a given shell of an atom on its outer shell electrons is (a) s > P> d> f (b) f> d> p>s (c) p < d< s> f (d) f>p>s>d