Just going over some past papers and came across this question (left) and ans (right) (attached)
I get why it forms Na+ but why doesn't it form a bond with the N- ?
Do you mean why isn't there a line between the N and the Na to show the bond?
Well, a line represents a single covalent bond, which is not the type of bonding present in this case; it would be an ionic bond, shown by the N- and Na+ charges. (In ionic bonds, you don't draw a line).