Ions

Ions

1. Atoms and ions

   • An atom has the same number of protons and electrons. It has no overall charge, because the positive charges on the protons are balanced by the negative charges on the electrons
     • An atom can become an ion by gaining or losing one or more electrons. An ion has a charge because it no longer has the same number of protons and electrons. We show that the atom has become an ion by adding a + or - sign to the symbol

2. Cations

   • Metal atoms lose electrons to form positively charged cations
     • Metals in group 1 lose 1 electron to form ions with a +1 charge
       • Metals in group 2 lose 2 electrons to form ions with a +2 charge

3. Anions

   • Non-metal atoms gain electrons to form negatively charged atoms
     • Elements in group 6 gain 2 electrons to form ions with a 2- charge
       • Elements in group 7 gain 1 electron to form ions with a 1- charge