How do I work out what the ionic charge is for different elements in the periodic table?

The useful thing is that different elements have been grouped together on the periodic table so that it's easy to see which ones share something in common. Group 1 elements become 1+, Group 2 becomes 2+, Group 3 becomes 3+, Group 4 becomes 4+, Group 5 becomes 3-, Group 6 becomes 2-, Group 7 becomes 1-, Group 8 is always 0 (inert). (n)+ means there're more protons (positively charged) than electrons (negatively charged). (n)- means the opposite. Look at the elements on the periodic table e.g. Na which has an atomic number of 11 (number of protons and therefore electrons - if both are equal it's a neutral charge). Remember protons and neutrons are in the nucleus; electrons orbit it in rings. The inner ring only holds 2; all subsequent rings hold 8. (DRAW OUT Na STRUCTURE) - 2 + 8 + 1 = 11. See that the outer ring only has 1 electron. Atoms like having full rings, so it's just easy if Na 'kicks' out that one electron becoming 2 + 8. This therefore means there's one less electron than there are protons hence Na+ charge in it's ionic form. In contrast Group 7 elements you will find (I will draw an example) it's easier to gain electrons from surroundings because their outer ring is nearly full, so they'll have more electrons than protons and therefore become negatively charged in their ionic state e.g. Fl-