From Atoms to Materials

What is inside an atom? After scientists found out that matter is made up of atoms, they began to ask the next question: what is inside an atom? Subatomic particles After many experiments, scientists propose that an atom consists of three types of smaller particles: • proton ; • electron ; and • neutron . These particles are known as subatomic particles*. Some of their properties are listed on the right. A Subatomic particle Relative mass Electric charge Proton 1 +1 Electron about 1 1840 −1 Neutron 1 0 Table 13.1 R elative mass and charge of subatomic particles Warm up oxygen gold As of March 2017, 118 elements were known. Among them, about 90 elements can be found in nature. The remaining elements are synthesized in the laboratory. proton 質子 electron 電子 neutron 中子 subatomic particle 次原子粒子 magnesium iron There are 118 types of atoms currently known to scientists. They correspond to 118 elements. How are atoms and elements related? In this section, we shall study atoms and elements in detail. 13.2 What atoms do they contain? Atoms are the basic units of matter (we learnt this in chapter 6). Here are some examples of elements. What atoms do they contain? Share your ideas with your classmates. 10 Atoms and elements 13.2 © 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