Chemically, we know Potassium is a lot like Lithium and Sodium What these elements (the alkali metals) have in common is an unpaired valence electron in an s orbital If Potassium has an unpaired electron in an s orbital it would mean that it is in the 4s orbital Thus, the 4s orbital would appear to be of lower energy than the 3d orbital(s) The 4s orbital would be filled when we have an element wit