What is the link between the group a metal is in and the charge on its ion?

Answer 1

Ions are electrically charged particles formed when atoms lose or gain electrons. They have the same electronic structures as noble gases.

Metal atoms form positive ions, while nonmetal atoms form negative ions. The strong electrostatic forces of attraction between oppositely charged ions are called ionic bonds.

Ionic compounds have high melting and boiling points.

How ions form Ions are electrically charged particles formed when atoms lose or gain electrons. This loss or gain leaves a complete highest energy level, so the electronic structure of an ion is the same as that of a noble gas - such as a helium, neon or argon.

Metal atoms and non-metal atoms go in opposite directions when they ionise:

• Metal atoms lose the electron, or electrons, in their highest energy level and become positively charged ions.
• Non-metal atoms gain an electron, or electrons, from another atom to become negatively charged ions.

Positively charged sodium and aluminium ions

Negatively charged oxide and chloride ions

How many charges?There is a quick way to work out what the charge on an ion should be:

• the number of charges on an ion formed by a metal is equal to the group number of the metal
• the number of charges on an ion formed by a non-metal is equal to the group number minus eight
• hydrogen forms H+ ions

Group 1Group 2Group 3Group 4Group 5Group 6Group 7Group 0Example elementNaMgAlCNOClHeCharge1+2+3+Note 13-2-1-Note 2Symbol of ionNa+Mg2+Al3+Note 1N3-O2-Cl-Note 2

Note 1: carbon and silicon in Group 4 usually form covalent bonds by sharing electrons.

Note 2: the elements in Group 0 do not react with other elements to form ions.