Passage IV

Atomic nuclei can be represented by the combination of symbols

where Z is the number of protons in a nucleus of Element X, and A (equal to Z plus the number of neutrons) is the mass number of the same nucleus. For example, represents a nucleus of carbon containing 6 protons and 6 neutrons;represents a nucleus of a different isotope (type) of carbon that contains 6 protons and 8 neutrons.

Atomic nuclei undergo 3 types of radioactive decay. Particles emitted during the 3 types of decay are listed in Table 1. Figure 1 shows a sequence of radioactive decays, called the uranium series, that begins with the decay of .