We can use Lewis Electron Dot Symbols to describe the ionic bonding
that is observed in sodium chloride, which is commonly known as table salt.
The formation of sodium chloride involves sodium
metal, Na and chlorine
gas, Cl2. The reaction can be thought of involving the following
The Oxidation of Sodium Metal
Sodium atoms lose its outer-shell electron
to become a sodium ion, (i.e. cation).
The sodium metal is said to be oxidized.
The diagram below shows two sodium atoms undergoing oxidation.
The Reduction of Chlorine Gas
Recall from section 4.7,
chlorine is a diatomic element. The covalently bonded Cl2 molecule
gains two electrons to become two chloride ions,
Chlorine is said to be reduced.
Combining the above oxidation and reduction processess, the overall effect
is the transfer of ONE electron from sodium
The oppositely charged sodium and chloride ions attract each other
and ionic bonds are formed. In the solid state,
each cation is surrounded by anions, and each anion is surrounded by cations.
These ions arrange themselves in a 3-dimensional
crystal. The simplest ratio of Na+ : Cl- is 1:1. The
simplest formula for this ionic compound is NaCl.