Calcium, which is in Period 2 and has 2 valence electrons, has an ion of Ca 2+
This is because it can give up the two electrons to get a full outer shell.
Nitrogen, on the other hand, has 5 valence electrons. To get a full outer shell, it can either gain 3 electrons or lose 5. Since it is easier to gain 3, Nitrogen usually gains 3 electrons to form a N3- ion.
Even though it is rare, it is possible for Nitrogen to form a positive ion, which is N5+
Hope I helped!! xx
