Please see chart:
Work Step by Step
For each row, the formula of the molecule must have a net charge of 0. So, once you look up the charge on each cation (positively charged) and anion (negatively charged), you need to balance the charges. For row one, you have a lithium ion with a charge of +1 and the oxide ion with charge -2. To have a net charge of 0, you would need two lithium ions and one oxide ion, for a formula of Li2O. Carry this process out for the whole table. When you come across roman numerals in parentheses next to an ion in the name, such as the (II) in Copper (II) Nitrate, that tells you the charge of the cation is in this case +2.