how do we get all other materials? aims: –to be able to classify materials as elements and...
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How do we get all other materials?
• Aims:
– To be able to classify materials as elements and non-elements
– To be able to describe simple compounds and molecules
Elements
• Elements are the simplest chemicals. They make up all other chemicals.
• Oxygen (O2) is an element:
• Elements have only one type of atom in their molecules
O O
Combining elementsHow is possible to have so many different materials from a limited number of elements?
Combining elements
How do you get so many different cheeses?
What is the key ingredient in all cheeses?
Milk is combined with a small number of ingredients under different conditions to make a huge number of different cheeses.
In a similar way, a small number of elements can be combined in many different ways to
make a huge number of different compounds.
Compounds
• Compounds are chemicals made when elements join together chemically.
• Water is a compound.
• Compounds have more than one type of atom in their molecules
H O H
Making a compound – carbon dioxide
A compound has very different properties to the elements from which it is made.
carbon dioxide
A colourless gas which is used
to put out fires.
to make
carbon
A black solid which can be
used as a fuel.
combines with
compound
elementsoxygen
A colourless gas which is essential
for life.
Making a compound – water What are the elements which make up water? In what ways are the elements different to their compound?
to makecombines with
compound
elementswater
A liquid which is essential to our lives and has
many different uses.
hydrogen
A colourless gas which is
used in hot air balloons.
A colourless gas which is essential
for life.
oxygen
More than one type of atom
• Elements join together to form compounds
• Water is a compound made from 2 elements– Hydrogen– Oxygen
• The smallest particle of water contains two atoms of hydrogen and one of oxygen– This is a molecule of water
Definitions
• Molecule– Two or more atoms joined together
• Compound– Chemicals made when two or more
elements join together chemically.
Element or compound?
Copy and complete the table
Sample name Element or compound
Type and number of
atoms in the molecule
water compound 2 hydrogen1 oxygen