From Atoms to Materials

(c) and (d) are two isotopes of carbon. Explore Exp (a) 16 O 8 protons electrons neutrons (b) 24 Mg 12 protons electrons neutrons (c) 1 2 C 6 protons electrons neutrons (d) 1 4 C 6 protons electrons neutrons • Atomic number is the number of protons in an atom. • Mass number is the sum of the numbers of protons and neutrons in an atom. 13.2 Atomic number and mass number What elements do these atoms belong to? 1. Write the numbers of protons, electrons and neutrons in these atoms. 2. For the following atoms, write the atomic symbols (with atomic number and mass number) by referring to Table 13.2 on p. 15. (a) (b) (c) 1 proton, 0 neutrons 1 electron 4 protons, 5 neutrons 4 electrons 7 protons, 7 neutrons 7 electrons 19 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