Elements, compounds & mixtures

1. D. Crowley, 2007

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

3. Look at the pictures below - is it an element or a
compound?
Element CompoundElement ElementCompound

4. How about this - element or compound?
Actually this is neither an element or a compound - it
is a mixture!

5. 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

6. Imagine coloured sweets which can be mixed together in a packet,
but are not chemically joined together
Mixture Element 1Element 2Element 3Element 4
You could easily separate these into their different colours -
without needing a chemical reaction…

7. 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!!!

8. 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 occurs
So the properties of the mixture is a mixture of all
the properties that make the mixture up!

9. 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

10. Look at the following - copy down the particle
boxes, and decide if it represents an element,
compound or mixture
Element CompoundElement Mixture Mixture

11. 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

12. 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

13. Try the online quiz: -
http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_test.shtml