Ionic Bonding
Ion: An electrically charged particle formed from an atom or group of atoms by
loss or gain of electrons
Ionic bonding
 Ionic compounds, eg. NaCl, consist of a regular arrangement of positive and
negative ions.
 Electrons from the metal atoms are transferred to the non-metal atoms so
that all the atoms have full outer shells.
 The metal atoms lose their outer shell electrons to become positively
charged.
 The non-metal atoms gain electrons to become negatively charged.
 We can show this by a dot and-cross diagram
 Examples
Sodium chloride (NaCl)
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Sodium lost one outer electron to gain a full outer shell of electrons forming
a positive sodium ion with the charge +1 is formed.
Chlorine gained an electron to have a full outer shell of electrons forming a
negatively charged chloride ion with a charge of -1.
One electron is transferred from the outer shell of the sodium atom to the
outer shell of the chlorine atom.
Magnesium oxide, MgO
Magnesium lost two electrons. These are transferred to the oxygen atom. In
magnesium oxide, the Mg2+ and O2− are oppositely charged and are attracted to
one another. The formula for magnesium oxide is MgO.
Calcium chloride (CaCl2)
The calcium atom gives each of the two chlorine atoms one electron.
In this case, a compound is formed containing two chloride ions (Cl−) for each
calcium ion (Ca2+). The chemical formula is CaCl2