All substances have a set of properties. Properties can be physical or chemical.
Properties
A property is how a substance looks or behaves. It is important to be aware of a substance's properties as this can allow you to select the most appropriate material for the job.
Example
Aluminium is used to make saucepans as it is a very good conductor of heat.
Physical properties
A physical change is when a substance changes its physical state from solid, liquid or gas. The process occurring can usually be observed.
Example 1
H2O going from liquid water to solid ice.
Example 2
Other examples of physical properties are: brittleness, whether a material is magnetic or not and melting/boiling point.
Chemical properties
A chemical change occurs during a chemical reaction. During the reaction, one or more new substances are formed. Chemical reactions cannot simply be observed just by looking at a material, you have to carry out a reaction or experiment.
Example
An example of measuring chemical properties is testing for pH of liquids.
Hydrochloric acid has a low pH between 0−2, which means it is acidic. Water has a ph of 7, this means it is neutral. Bleach on the other hand has a pH of 12−13, therefore it is alkaline.