Final answer:
Radioactive decay most commonly changes the atomic number of the nucleus, transforming one element into another through processes such as alpha and beta decay. Alpha decay decreases the atomic number by 2, whereas beta decay increases it by 1. Gamma decay releases energy but does not change the atomic number or mass number.
Step-by-step explanation:
The best statement that describes the effect of radioactive decay on a nucleus is: "Radioactive decay changes the atomic number of the nucleus." There are several forms of radioactive decay, such as alpha decay, beta decay, and gamma decay, each of which impacts the nucleus differently:
- In alpha decay, the nucleus emits an alpha particle (two protons and two neutrons), leading to a decrease in the atomic number by 2 and a decrease in the mass number by 4.
- Beta decay involves the transformation of a neutron into a proton, with the emission of a beta particle (electron) resulting in an increase in the atomic number by 1 without a change in mass number.
- In the case of gamma decay, there is no change in the atomic number or the mass number; instead, gamma radiation is emitted, which is a form of energy release as the nucleus goes from a higher energy state to a lower energy state.
Therefore, while radioactive decay can alter the mass of the nucleus (as in alpha decay) and indeed may lead to more stable energy states, the defining effect of radioactive decay is the transformation of one element into another, characterized by a change in the atomic number due to alterations in the number of protons in the nucleus.