Balancing Nuclear Equations

Radioactive nucleus - A nucleus that spontaneously changes and emits (releases) energy.

This occurs spontaneously: by itself and with no outside energy required. You don't always have to "split an atom." Many isotopes do it naturally. A radioactive nucleus spontaneously changes into a different nucleus, releasing other particles and energy in the process. This occurs randomly and without any outside source of energy.

You might wonder what happens to the electrons. They get redistributed in the process of the nuclear change, but we don't usually worry about them when writing nuclear reactions.

Not all isotopes are radioactive. We'll learn how to predict whether an isotope is radioactive on the next page.