All atoms want to have a full outer shell of electrons.
This is 2 on the first shell and 8 on the rest of the shells.
This is Neon. He is a stable atom.
This makes him happy!
Why is he stable?
lithium
These atoms are all unstable as
beryllium
they do notfluorine
have full outer shells sodium
of
electrons.
chlorine
What could you suggest to help
them out?
hydrogen
oxygen
Chlorine has gained an electron.
It now has a -1 charge
Sodium has lost an electron.
It now has a +1 charge
XX
XX
sodium
chlorine
X
X
ionic bond
X
X
X
X
X
X
X
XX
XX
Sodium is stable
Chlorine is stable
8 electrons in outer shell
8 electrons in outer shell
They are now bonded together to make a compound
called sodium chloride. This giving and taking of
electrons is called ionic bonding.
METAL
One electron donated
One electron
accepted
NaCl sodium chloride
NON-METAL
Ionic Bonding
• Normally happens between non-metals and metals.
• Ionic bonding is a transfer of electrons
• Metals always produce positive ions.
• Non-metals always produce negative ions.
Calcium has lost two electrons.
It now has a +2 charge
Oxygen has gained two electrons.
It now has a -2 charge
XX
calcium
oxygen
X
X
X
ionic bond
X
XX
Calcium is stable
Oxygen is stable
8 electrons in outer shell
8 electrons in outer shell
They are now bonded together to make a compound
called calcium oxide. This giving and taking of
electrons is called ionic bonding.
Working out the Formula of an Ionic Compound
Positive Ions
All Group 1 All Group 2
Li +
Na +
K+
Mg 2+
Ca 2+
Negative ions
2- ions
1- ions
Carbonate CO32Sulphate SO42All Group 6
O2-
Hydroxide OHNitrate NO3All Group 7
F-
S2-
ClBrI-
Working out the Formula of an Ionic
Compound
The charges of the ions in a compound have to balance.
For example,
What is the formula of sodium hydroxide?
Sodium ion is Na+
Hydroxide ion is OHYou only need one of each ion to balance the charges so
the formula of sodium hydroxide is NaOH.
Working out the Formula of an Ionic
Compound
The charges of the ions in a compound have to balance.
For example,
What is the formula of magnesium chloride?
Magnesium ion is Mg 2+
Chloride ion is ClYou need two Chloride ions to balance the charge of one
Magnesium ion so the formula of magnesium chloride is
MgCl2.
Work out the Formulae
Try the exercises on the worksheet