The size of the ions

The diameter of ions can be very different: - In a group (column) of the periodic table the diameter of ions having the same charge increases from top to bottom because the number of electrons increases too. - In a period (line) of the periodic table, it appears that positive ions are smaller: The positive charge attracts the electrons towards the nucleus even more than the positive charge is greater. On the contrary, negative ions are bigger: The global negative charge repels the electrons even more than the negative charge is greater (in absolute value ).