4 Energy 2
4.1 Different Forms of Energy 2
4.2 Energy Changes 7
4.3 Fuels 15
4.4 Generating Electricity 24
4.5 Energy and Us 36
Summary 41
Glossary 41
Key Points 42
Test yourself 44
5 Water 52
5.1 Water Purification 52
5.2 Further Treatment of Water 62
5.3 The Water Cycle 67
5.4 Water Conservation and Pollution 75
5.5 Dissolving 88
5.6 Growing Crystals 97
5.7 Solvents Other than Water 101
Summary 104
Glossary 104
Key Points 105
Test yourself 108
6 Matter 115
6.1 States of Matter 115
6.2 Particle Theory of Matter 125
6.3 The Particle Model 133
6.4 Gas Pressure 139
6.5 Density 145
6.6 Expansion and Contraction 153
Summary 164
Glossary 164
Key Points 165
Test yourself 168
Index 172