| Magnesium is a Group II-A element; therefore, it will have a +2 charge on
the magnesium ion. Oxygen is in Group VI-A. It has six electrons in its outer shell. It
has room for two more so when it forms an ion, it has a -2 charge and it is called an
oxide ion. Here again, we have equal charges on the two ions: a +2 on the magnesium and a
-2 charge on the oxygen. So they will combine in a 1:1 ratio and the formula for that
compound is MgO. It is called magnesium oxide because it is made of magnesium ions and
oxide ions. |
| Ions |
Mg2+ |
O2- |
Simplified
charge ratio |
1 |
1 |
| Ion ratio |
1 |
1 |
| Formula |
MgO |
|
