http://www.ck12.org Chapter 11. Nuclear Chemistry
FIGURE 11.7
In beta decay, an electron and a proton form from a neutron (another
unusual particle, called an antineutrino, is also produced). Only the
electron is emitted from the nucleus. How does this change the atomic
number and atomic mass of the atom?234
90 Th→234
91 Pa+0
− 1 e+EnergyThe protactinium-234 produced in this reaction is radioactive and decays to another element. The electron produced
in the reaction (plus another electron) can combine with an alpha particle to form helium.
Problem Solving
Problem:Fill in the missing subscript and superscript in this nuclear equation:^13153 I→??Xe+−^01 e+Energy
Solution:The subscript is 54, and the superscript is 131.
You Try It!
Problem:Fill in the missing subscript and superscript in this nuclear equation:^14 ?C→? 7 N+−^01 e+Energy
Gamma Decay
In alpha and beta decay, both particles and energy are emitted. In gamma decay, only energy is emitted. Gamma
decay occurs when an unstable nucleus gives off gamma rays. Gamma rays, like rays of visible light and X-rays,
are waves of energy that travel through space at the speed of light. Gamma rays have the greatest amount of energy
of all such waves. By itself, gamma decay doesn’t cause one element to change into another, but it is released in
nuclear reactions that do. Some of the energy released in alpha and beta decay is in the form of gamma rays. You
can learn more about gamma radiation at this URL: http://www.youtube.com/watch?v=okyynBaSOtA (2:45).
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5015Comparing Types of Radiation
The different types of radiation vary in how far they are able to travel and what they can penetrate (seeFigure11.8
and the URL below).