If Al = +3 and Cl = -1, then why does it combined =AlCl(subscript3)??

Question

also if N= -3 and H= +3 why does it combined = NH(subscript3)

ok so does that mean Fr1 combined with S-2 = FrS-2 ?

and

Ca+2 combined with Br-1 = CaBr-2?

Answer 1

Because you need 3 -1 oxidation bonds in order to satify the AL +3

If you cris cross the two oxidation numbers and make them subscripts then yo have the compound

ex/ Al^3Cl^-1 --> AlClsub3

Thus for N and H you get Nsub3Hsub3 but the 3's reduce so you are left with NH

Answer 2

Plusses equal minuses. Al+++ must equal 3Cl-. So AlCl3

N = -3, but H = +1. So it takes 3 +1's to equal a -3. NH3