Physics » Radioactivity and Nuclear Physics » Nuclear Decay and Conservation Laws

# Summarizing Nuclear Decay and Conservation Laws

## Nuclear Decay and Conservation Laws Summary

• When a parent nucleus decays, it produces a daughter nucleus following rules and conservation laws. There are three major types of nuclear decay, called alpha $$(\alpha ),$$ beta $$(\beta ),$$ and gamma $$(\gamma )$$. The $$\alpha$$ decay equation is

$${}_{Z}^{A}{X}_{N}\to {}_{Z-2}^{A-4}{\text{Y}}_{N-2}+{}_{2}^{4}{\text{He}}_{2}.$$

• Nuclear decay releases an amount of energy $$E$$ related to the mass destroyed $$\Delta m$$ by

$$E=(\Delta m){c}^{2}.$$

• There are three forms of beta decay. The $${\beta }^{-}$$decay equation is

$${}_{Z}^{A}{X}_{N}\to {}_{Z+1}^{A}{\text{Y}}_{N-1}+{\beta }^{-}+{\overline{\nu }}_{e}.$$

• The $${\beta }^{+}$$ decay equation is

$${}_{Z}^{A}{X}_{N}\to {}_{Z-1}^{A}{\text{Y}}_{N+1}+{\beta }^{+}+{\nu }_{e}.$$

• The electron capture equation is

$${}_{Z}^{A}{X}_{N}+{e}^{-}\to {}_{Z-1}^{A}{\text{Y}}_{N+1}+{\nu }_{e}.$$

• $${\beta }^{-}$$ is an electron, $${\beta }^{+}$$ is an antielectron or positron, $${\nu }_{e}$$ represents an electron’s neutrino, and $${\overline{\nu }}_{e}$$ is an electron’s antineutrino. In addition to all previously known conservation laws, two new ones arise— conservation of electron family number and conservation of the total number of nucleons. The $$\gamma$$ decay equation is

$${}_{Z}{}^{A}\text{}{\text{X}}_{N}^{*}\to {}_{Z}{}^{A}\text{}{\text{X}}_{N}+{\gamma }_{1}+{\gamma }_{2}+\cdots$$

$$\gamma$$ is a high-energy photon originating in a nucleus.

## Glossary

### parent

the original state of nucleus before decay

### daughter

the nucleus obtained when parent nucleus decays and produces another nucleus following the rules and the conservation laws

### positron

the particle that results from positive beta decay; also known as an antielectron

### decay

the process by which an atomic nucleus of an unstable atom loses mass and energy by emitting ionizing particles

### alpha decay

type of radioactive decay in which an atomic nucleus emits an alpha particle

### beta decay

type of radioactive decay in which an atomic nucleus emits a beta particle

### gamma decay

type of radioactive decay in which an atomic nucleus emits a gamma particle

### decay equation

the equation to find out how much of a radioactive material is left after a given period of time

### nuclear reaction energy

the energy created in a nuclear reaction

### neutrino

an electrically neutral, weakly interacting elementary subatomic particle

### electron’s antineutrino

antiparticle of electron’s neutrino

### positron decay

type of beta decay in which a proton is converted to a neutron, releasing a positron and a neutrino

### antielectron

another term for positron

### decay series

process whereby subsequent nuclides decay until a stable nuclide is produced

### electron’s neutrino

a subatomic elementary particle which has no net electric charge

### antimatter

composed of antiparticles

### electron capture

the process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino

### electron capture equation

equation representing the electron capture