From Atoms to Materials

D. Overview of elements, compounds and mixtures (p. 52) 7. E. Writing balanced chemical equations (p. 55) 8. We can write a chemical equation to represent a chemical reaction. 13.5 Metals and alloys A. How are the uses of metals related to their properties? (p. 60) 1. Although metals have common properties, the properties of different metals may vary. 2. The uses of metals are closely related to their properties. B. How do we obtain metals? (p. 65) 3. Metals can be extracted from metal ores in the Earth’s crust. 4. Most metals exist in the form of compounds in their ores. Only a few metals (e.g. gold and platinum) exist in the form of elements in their ores. 5. Some metals exist as elements in their ores. They can be extracted using physical methods. 6. Some metals exist as compounds in their ores. They can be extracted using chemical methods. 7. Some metals (e.g. copper and iron) can be extracted by heating their oxides with carbon. This method is called carbon reduction. Chapter Review 13 From Atoms to Materials 109 Element Compound Mixture Composition •  a pure substance •  cannot be broken down into simpler substances through chemical reactions •  a pure substance •  made up of two or more elements chemically combined together •  not a pure substance •  consists of two or more pure substances that are not chemically combined together Changes during formation — A chemical change takes place. A physical change takes place. Properties Each element has its own properties. Its properties are different from those of its constituent elements. Each constituent substance keeps its own properties. Examples oxygen, hydrogen water, carbon dioxide air, sea water © United Prime Educational Publishing (HK) Limited 2024 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publisher. Sam le