Natural Radioactive Decay Series—Nuclear Equations

6 Natural Radioactive Decay Series—Nuclear Equations 

7 Given the identity of a radioactive isotope and the particle it emits, write a nuclear equation for the emission. 

When a radionuclide emits an alpha or beta particle, there is a transmutation of an element, that is, a change from one element to another. This means that the remaining nuclide has a different atomic number—a different number of protons—from the original nuclide. A nuclear change—actually a nuclear reaction— has occurred. The original substance (nuclide) has been destroyed and a new substance (nuclide) has been formed. 

The emission of a gamma ray does not change the elemental identity of the nucleus, even though energy is released. In that sense, a gamma emission, by itself, is not a nuclear change. Therefore, for the remainder of this chapter we will consider only alpha and beta emissions in nuclear reactions. 

As chemists write chemical equations to describe chemical changes, they write nuclear equations to describe nuclear changes. A nuclear equation shows the reactant nuclides or particles on the left and the product nuclides or particles on the right. The first step in the natural radioactive series observed by Becquerel is an alpha decay reaction. In it, a nucleus disintegrates, or decays, into a He nucleus (alpha particle) and a nucleus. The nuclear equation is 

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Section 20.6 Natural Radioactive Decay Series—Nuclear Equations... 

We use X to indicate any element defined by its nuclear charge, Z and Z-2 in this equation. Examples are given in Ch. 1, and can be found e.g. in the natural radioactive decay series, see next chapter. 

Radioactive nuclei emit a particles, 13 particles, positrons, or y rays. The equation for a nuclear reaction includes the particles emitted, and both the mass numbers and the atomic numbers must balance. Uranium-238 is the parent of a natural radioactive decay series. A number of radioactive isotopes, such as and C, can be used to date objects. Artificially radioactive elements are created by the bombardment of other elements by accelerated neutrons, protons, or a particles. Nuclear fission is the splitting of a large nucleus into smaller nuclei plus neutrons. When these neutrons are captured efficiently by other nuclei, an uncontrollable chain reaction can occur. Nuclear reactors use the heat... 

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