1. Thermal Expansion is
the tendency of
matter to change in
volume in response to
a change in

2. When a substance is heated, its particles begin
moving more and thus usually maintain a greater
average separation. Materials which contract with
increasing temperature are unusual; this effect is
limited in size ,and only occurs within limited
temperature ranges . The degree of expansion
divided by the change in temperature is called the
material’s coefficient of thermal expansion and
generally varies with temperature.

3. Thermal Expansion decreases with increasing
Bond Energy.
 Thermal Expansion decreases with Melting point.
 Unlike gases or liquids, solids tend to keep their
shape when undergoing thermal expansion.
Thermal Expansion of glasses is higher
compared to that of crystals.
 Absorption or desorption of water can also effect
thermal expansion.

4. The coefficient of thermal expansion describes how the size of
an object changes with a change in temperature.
In general case of a gas , liquid , or solid the volumetric coefficient of
thermal expansion is given by ;

5. Materials change their size when subjected to a temperature change
while the pressure is held constant.
It is the change in length measurements of an object due to
thermal expansion. It’s coefficient is ;
It is the fractional change in area per degree of temperature
change. It’s coefficient is ;