Matter is anything that occupies space and has mass.
All liquids, solids and gases are matter.
A particular sample of matter may be a pure substance or a mixture.
Pure substances have a uniform composition (the same throughout) and cannot be separated into simpler substances by physical means (such as filtration or distillation).
Two common examples of pure substances are table salt and sugar.
Mixtures contain one or more pure substances and can be separated into their components using physical means.
The components of a
heterogeneous mixture can often be seen with the naked eye.
A mixture of sand and sea water can be separated by filtration.
Homogeneous mixtures have a uniform composition.
Air is a homogeneous mixture of the gases nitrogen and oxygen.
may be classed as compounds or
elements.
Elements have only one type of atom.
The gas oxygen is an example of an element because it is composed of only oxygen atoms.
Elements may not be separated into simpler substances by either physical or chemical means.
Compounds have more than one type of atom.
Table salt is a compound because it has two types of atoms (sodium and chlorine).
Compounds may be separated into their elements using chemical means.
In both pure substances and elements the atoms are joined by attractive forces known as chemical bonds.