Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 33 - Think and Explain: 66


The new atomic number is 86 and the new mass number is 222.

Work Step by Step

The atomic number decreases by 2 for alpha emission, because alpha particles carry a charge of +2e. The radium atom becomes a radon atom. The mass number decreases by 4 for alpha emission, because alpha particles have 4 nucleons. This is discussed on pages 628-629. The periodic table on page 216 is also helpful.
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