How do i assign oxidation states for atoms in a compound with more than 2 elements?
Well Mg is always +2 and O is always -2 2(+2)=+4 and 7(-2)=-14 so all you need to find now is the oxidation number of P (sum must be 0) Mg2P2|O7=0 +4 |-14= 0 +4 doesn’t equal -14, so you need to figure out what number does; you find that it is +10 now you see that +10/2 = +5 and that is how you find the oxidation number for P +4 +10 | -14 = 0 Mg = +2, O = -2, and P = +5