Use group number to work out the charge on ions from Group 1, Group 2, Group 6 and Group 7 elements.

The charge on ions can be determined using the group number of the elements in the periodic table. For Group 1 elements, such as sodium, they lose one electron to form a +1 ion. Group 2 elements, like magnesium, lose two electrons, resulting in a +2 ion. Conversely, Group 6 elements, such as oxygen, gain two electrons to form a -2 ion, while Group 7 elements, like chlorine, gain one electron to create a -1 ion. This relationship between group number and ion charge helps predict the behavior of elements during ionic bonding.