How many covalent bonds do nitrogen atoms make and why?

Nitrogen makes 3 covalent bonds. It is in the second period of the periodic table and so has its outer electron in the second shell/energy level. This shell requires eight electrons in order to be filled.A full shell is a low energy/ stable arrangement of electrons and so atoms 'want' a full outer shell. Nitrogen is also in group 5 of the periodic table and so requires 3 more electrons to fill its' outer shell. Each covalent bond contains two electrons, one from each of the bonded atoms. Thus each covalent bond formed by an atom adds one additional electron to its' outer shell. Nitrogen thus makes 3 covalent bonds.