From Atoms to Materials

Fig. 13.5 A simple model of the atom (not drawn to scale) (positively charged particle in the nucleus) (electrically neutral particle in the nucleus) (negatively charged particles around the nucleus) From Table 13.1 on p. 10, we see that: • A proton and a neutron have about the same mass. Compared to them, an electron is much lighter. • A proton is positively charged, an electron is negatively charged, and a neutron has no charge (or is neutral). Simple model of an atom To show the structure of an atom, scientists have constructed atomic models . In a simplified atomic model, its centre is a small, dense region called the nucleus . Protons and neutrons are packed tightly together in the nucleus. Electrons occupy the space outside the nucleus. As protons are positively charged, and neutrons have no charge, the nucleus is positively charged. The space occupied by electrons in an atom is much larger than the nucleus. This space is known as an ‘electron cloud’. It is negatively charged. atomic model 原子模型 nucleus 原子核 Write down the names of subatomic particles. (a) (b) (c) nucleus 11 13 From Atoms to Materials © 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