D. Crowley, 2007

To understand the difference between an element, a compound and a mixture

Look at the pictures below - is it an element or a compound?

Element CompoundElement Element Compound

How about this - element or compound?

Actually this is neither an element or a compound - it is a mixture!

How can we describe a mixture?

Remember: an element is made up of just one type of atom

A compound is two or more elements which are chemically bound together…

A mixture is made from different substances which are not chemically bound

Imagine coloured sweets which can be mixed together in a packet, but are not chemically joined together

Mixture Element 1 Element 2 Element 3 Element 4

You could easily separate these into their different colours - without needing a chemical reaction…

A mixture is made from different substances, which are not chemically bound

E.g. air is a mixture of gases

The gases (oxygen; nitrogen; argon; and carbon dioxide) can be easily separated

The properties of the mixture are just a mixture of the properties of the separate parts!!!

Remember, in a compound a chemical reaction binds the substances together.

This means the properties of the newly formed compound are different from the original elements

In a mixture no chemical reaction occursSo the properties of the mixture is a

mixture of all the properties that make the mixture up!

E.g. a mixture of iron powder and sulphur powder will show properties of both iron and sulphur!

This means our mixture will contain grey magnetic bits of iron + yellow bits of sulphur

Look at the following - copy down the particle boxes, and decide if it represents an element, compound or mixture

Element CompoundElement Mixture Mixture

An element contains just one type of atom

A compound contains two or more types of atoms that are chemically bound

A mixture contains two or more different substances, that are not chemically bound

The different substances in a mixture can be elements or compounds

Copy out the table, given a description of the diagram (e.g. pure element, mixture of elements, compound etc…)

Add an example to your description

Diagram Description Example

Pure element

Pure compound

Mixture of elements

Mixture of compounds

Mixture of elements & compounds

Oxygen

Carbon dioxide

Oxygen & Helium

Alcohol & Water

Air

Try the online quiz: -

http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_test.shtml