Magnesium is almost always +2. with an electron configuration of
1s22s22p3s2 Magnesium tends to lose the two 3s electrons. This leaves magnesium with the stable electron configuration of Neon and a positive 2 charge.
Oxygen is almost always -2 with an electron configuration of
1s22s22p4. Oxygen with a high electro negativity tends to gain to electrons. This leaves Oxygen with the stable electron configuration of Neon and a negatitive 2 charge.
The polyatomic ion of NO2 nitrite has a net charge of -1. The charge of the nitrogen can be calculated using the equation.
1×N+2×O=−1 The charge on Oxygen -2 can be put in for O
1×N+2×−2=−1 This gives
N+−4=−1 adding +4 from both sides gives
N+−4+4=−1+4 This gives
N = +3
