Radioactivity and Man-Made Radioactive Decay

For purposes of this book, I define radioactivity as the spontaneous decay of an unstable nucleus. An unstable nucleus may break apart into two or more other particles with the release of some energy (see Gone (Nuclear) Fission, later in this chapter, for more info on this process). This breaking apart can occur in a number of ways, depending on the particular atom that s decaying. 

You can often predict one of the particles of a radioactive decay by knowing the other particle. Doing so involves something called balancing the nuclear reaction. (A nuclear reaction is any reaction involving a change in nuclear structure.) 

Balancing a nuclear reaction is really a fairly simple process. But before 1 explain it, 1 want to show you how to represent a reaction  

Reactants are the substances you start with, and products are the new substances being formed. The arrow, called a reaction arrow, indicates that a reaction has taken place. 

For a nuclear reaction to be balanced, the sum of all the atomic numbers on the left-hand side of the reaction arrow must equal the sum of all the atomic numbers on the right-hand side of the arrow. The same is true for the sums of the mass numbers. Here s an example Suppose you re a scientist performing a nuclear reaction by bombarding a particular isotope of chlorine (Cl-35) with a neutron. (Work with me here. I m just trying to get to a point.) You observe that an isotope of hydrogen, H-1, is created along with another isotope, and you want to figure out what the other isotope is. The equation for this example is 

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If this subtraction stuff confuses you, check out how to balance equations in the section Radioactivity and Man-Made Radioactive Decay, earlier in this chapter.)... 

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