1. 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

2. Elements Elements are the simplest chemicals. They make up all other chemicals. Oxygen (O 2 ) is an element: Elements have only one type of atom in their molecules O O

3. Combining elements How is possible to have so many different materials from a limited number of elements?

4. 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.

5. 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

6. 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 compoundelements oxygen A colourless gas which is essential for life.

7. Making a compound – water What are the elements which make up water? In what ways are the elements different to their compound? to make combines with compoundelements water 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

8. 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

9. Definitions Molecule –Two or more atoms joined together Compound –Chemicals made when two or more elements join together chemically.

10. Element or compound?

12. Copy and complete the table Sample nameElement or compound Type and number of atoms in the molecule watercompound2 hydrogen 1 oxygen