The charge of an element is based on how many valence electrons is on the outer most shell. The goal is to get to 8 valence electrons to make an element stable. If the element is to the far right of the periodic table (blue section), they already have 8 so they are stable and do not have a charge.
The Charge of an Element
The charge of an element depends on where it is located on the Periodic table. If they are located all the way to the left (red), they have a +1 charge. Next to red, the next group is tan. The tan colored elements have a +2 charge. If you skip over all the transition medals from groups 3-12, group 13 has a charge of +3. The next group has a +4 charge and so on.
The Charge of Transition Metals
The charge of transition metals are not as simple to learn as the other groups of elements. There is no set rule for where they line up and what charge they have. This site will tell you the charges.
Another thing to keep in mind is that the charge is usually shown in a compound. For example, Lead(II) nitrate will show you that lead has a +2 charge. Anytime there is roman numerals behind the element, that is the charge. Another example would be Lead(IV) oxide. In the compound, lead has a +4 charge. So in these examples, you can see that lead can either have a +2 or +4 charge.
How reactive an element is depends on how many electrons they have in the outer shell. If they have 1 or 7, they are very reactive. If they have 2 or 6, they are still pretty reactive. 3 or 6, they are not as reactive. If they have 4, they are not very reactive. Since the goal is to have 8 valence electrons, elements with 1,2 or 3, want to lose theirs. Elements with 5,6, or 7 valence electrons want to gain electrons until they have 8. If an element has 4 valence electrons, they don’t lose or gain electrons. They share instead.
Hopefully this helped you understand the charges of electrons a little more.