From Atoms to Materials

Snapshot How to separate mixtures? Constituents of a mixture may be separated by physical methods, while those of a compound may not. Below are some examples of separating mixtures using physical methods: Overview of elements, compounds and mixtures Table 13.8 summarizes the main differences between elements, compounds and mixtures. 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 Table 13.8 Differences between elements, compounds and mixtures D What other mixtures can be separated by these methods? evaporation (e.g. obtaining a salt from its solution) filtration (e.g. separating insoluble impurities from muddy water) distillation (e.g. obtaining distilled water from muddy water) heating heating 52 © 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