Conceptual Physics (12th Edition)

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

Chapter 33 - Think and Explain - Page 635-636: 74


Strontium-90 (atomic number 38) should become yttrium-90 (atomic number 39) after beta emission.

Work Step by Step

The atomic number increases by 1 for beta emission, because beta particles carry a charge of -1e. A neutron in the nucleus effectively becomes a proton. This is discussed on pages 628-629. The periodic table on page 216 is also helpful. The physicist can test the strontium sample for any yttrium, perhaps by using chemical tests, a mass spectrometer, or other means. To verify that the strontium is a pure beta emitter, she will have to rule out alpha or gamma emission. The radiation detectors described on pages 626-627 will help in that regard. Bubble chambers can distinguish between positively-charged alpha particles and negatively-charged betas, and a scintillation counter is sensitive to gamma radiation.
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