From Atoms to Materials

physical method 物理方法 chemical method 化學方法 Fig. 13.23 Some common metal ores in which the metals exist in the form of elements Recall physical changes and chemical changes on p. 49. • Metals can be extracted from metal ores in the Earth’s crust. • 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. Extracting metals from their ores Depending on whether metals exist as elements or compounds in their ores, different methods are used to extract them. Extraction methods can be classified into physical methods and chemical methods . 1. Physical methods Some metals exist as elements in their ores. They can be extracted by physical methods. When a physical method is carried out, no new substance is formed . For example, the extraction of gold involves a physical method. See Fig. 13.24 on the next page. However, some metals exist as elements in their ores. gold ore platinum ore platinum grain Silver may also be found as an element in some ores. platinum gold gold 66 © 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. Sample