Chemistry: The Central Science (13th Edition)

Published by Prentice Hall
ISBN 10: 0321910419
ISBN 13: 978-0-32191-041-7

Chapter 21 - Nuclear Chemistry - Exercises - Page 947: 21.21a


Potassium - 40 is the radioisotope. It contains 21 neutrons as compared to K-39's 20 which makes it unstable. It, however, is a very long lived isotope.

Work Step by Step

Potassium - 39 is the stable isotope because its ratio of Neutrons to Protons is perfect for stability.
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