That is a wonderful question that has so many
As you know, everything is made up of atoms and
becomes what we call "matter".
Depending on the arrangement of those atoms,
different things will have different properties.
For example, if atoms or molecules are very far
apart, the substance will typically be a gas.
If the atoms are very tightly packed together, you
will get a solid.
If the distance is somewhere in between, then you
will have a liquid.
This is an example of a physical property -
which are the properties that you can measure
without altering the thing you are dealing with.
Mass, density, temperature, volume, and color are
some examples of physical properties.
Chemical properties are the ones that give
you information about how something behaves when
they react with something else (i.e. during or
after a chemical reaction).
An example of this is heat of combustion,
which is the amount of energy that is released
when you burn something under a set of specific
You would not be able to measure the heat of
combustion without going through a chemical
reaction with the oxygen in the air first!
This is what makes heat of combustion a chemical
By knowing the physical and chemical properties,
you can select the best material for any application!
If you want to build a bridge, you would pick a
strong material that would be able to hold the
weight of many cars and people and would also
withstand the temperatures of the city in which
you are building it.
These are things that many scientists
(especially chemists and materials scientists)
work with everyday!