Year 8 Science

1
Year 8 Science

• Mixtures Compounds

2
AIMS

• To understand the differences between elements
  and compounds
• To know what the differences are between mixtures
  and compounds
• To be able to recognise elements, mixtures and
  compounds from pictures of their particles

3
Elements
carbon bromine chlorine
mercury
silicon copper
uranium krypton
4
Elements

• Elements have only _______ type of atom
• Elements are the ___________ substances that can
  exist.
• The whole universe is made from about _____
  different elements.

5
Compounds
water (hydrogen oxide) salt (sodium
chloride) ammonia
rust (iron oxide) chalk
(calcium carbonate) sugar (glucose)
6
Compounds

• Most elements do ____ exist on their own
• They join with other ___________ to form
  ____________ .
• Compounds may have __________ different types of
  element in them.

7
Mixtures

• Iron and sulphur the mixture
• How can we separate the iron from the sulphur?

8
Mixtures

• Iron and sulphur the mixture
• How can we separate the iron from the sulphur?

9
Turning an iron-sulphur mixture into a new
compound
Iron-sulphur mixture
10
When iron and sulphur react

sulphur (S) atoms
iron (Fe) atoms
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When iron and sulphur react

sulphur (S) atoms
iron (Fe) atoms
iron sulphide (FeS) molecules
12
Differences between compounds and mixtures
MIXTURES
COMPOUNDS

• Mixtures can be separated easily

• Compounds can not be separated

13
Differences between compounds and mixtures
MIXTURES
COMPOUNDS

• Mixtures can be separated easily
• Mixture have the properties of the substances
  present in it

• Compounds can not be separated
• Compounds do not have the properties of the
  elements

14
Differences between compounds and mixtures
MIXTURES
COMPOUNDS

• Mixtures can be separated easily
• Mixture have the properties of the substances
  present in it
• No chemical change takes place when a mixture is
  made

• Compounds can not be separated
• Compounds do not have the properties of the
  elements
• A compound is always formed due to a chemical
  reaction

15
Differences between compounds and mixtures
MIXTURES
COMPOUNDS

• Mixtures can be separated easily
• Mixture have the properties of the substances
  present in it
• No chemical change takes place when a mixture is
  made
• There is no heat taken in or given out when a
  mixture is made

• Compounds can not be separated
• Compounds do not have the properties of the
  elements
• A compound is always formed due to a chemical
  reaction
• Heat is either taken in or given out when a
  compound is made

16
Differences between compounds and mixtures
MIXTURES
COMPOUNDS

• Mixtures can be separated easily
• Mixture have the properties of the substances
  present in it
• No chemical change takes place when a mixture is
  made
• There is no heat taken in or given out when a
  mixture is made
• A mixture can contain elements in any proportion

• Compounds can not be separated
• Compounds do not have the properties of the
  elements
• A compound is always formed due to a chemical
  reaction
• Heat is either taken in or given out when a
  compound is made
• A compound always contains the elements in fixed
  proportions, e.g. FeS contains 7g of iron to 4g
  of sulphur

17
Spotlight Science 8, page 28

• Draw boxes (a) to (e) off p28 NEATLY in your
  books.
• Write the correct description underneath each
  box.
• Answer questions 1, 2 and 4 off the bottom of p29