To answer this question you need to be familiar with the atoms with predictable single charges. These are given on the table below. Notice ...
Notice that atoms in group 1 only form ions of charge +1. In a similar way, atoms in group 2 form ions of charge +2 (except from Beryllium).
In group 3, aluminum is the only atom that forms a single charge ion, that is +3.
In group 5, nitrogen is the only atom that forms a single charge ion, that is -3.
Most atoms in groups 6 and 7 form single charge ions, which are -2 and -1, respectively.
If you are familiar with the groups and atoms that can generate ions with a single charge,
you can easily determine the ions that produce species with multiple charges.
Example,
Which atom can form ions of different charges?
a) Al b) Ba c) Sn d) K e) Cs
Solution
1. remember the groups on the periodic table with predictable single charges
2. eliminate the atoms with predictable single charges
3. you will end up with the atoms capable of forming multiple charges
