What would be the name of the compound, in terms of letters and in terms of chemical symbols?

Lithium nitride and li3n.

All ionic compounds have the metal first, and the nonmetal second. the nonmetal always ends in -ide. So lithium and nitrogen would create lithium nitride. nitrogen needs 3 electrons, and one atom of lithium can only give 1 electron. So, there needs to be three atoms of lithium to give 3 electrons to one atom of nitrogen. so, you put 3 in front of lithium to say that there has to be 3 lithium electrons. You don't put anything in front of nitrogen because there is only 1 atom needed. So, the formula will be li3n.