Is li3n ionic or covalent

Li₃N is Ionic compound.

Explanation:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.  

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

For example:

Lithium nitride is ionic compound. The electronegativity of Li is 0.98 and for nitrogen is 3.04. There is large difference is present. That's why electron from Li is transfer to the nitrogen. Lithium becomes positive and nitrogen becomes negative ion. Both atoms are bonded together electrostatic attraction occur between anion and cations.

while

Covalent bond:

It is formed by the sharing of electron pair between bonded atoms.  

The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.