radioactive decay

There are three types of natural radioactive decay. They are alpha emisson, beta emission, and gamma emission. The two types of artificial radiation are positron emission and electron capture. Alpha emission results in releasing an alpha particle. An alpha particle has two protons and two neutrons, so it has a positive charge. (Since it has two protons it is a helium nucleus.) It is written in equations like this:
alpha particle

beta emission

Beta emission is when a high speed electron (negative charge) leaves the nucleus. Beta emission occurs in elements with more neutons than protons, so a neutron splits into a proton and an electron. The proton stays in the nucleus and the electron is emitted. Negative electrons are represented as follows:
electron

gamma emission

Gamma Emission is when an excited nucleus gives off a ray in the gamma part of the spectrum. A gamma ray has no mass and no charge. This often occurs in radioactive elements because the other types of emission can result in an excited nucleus. Gamma rays are represented with the following symbol.
gamma ray symbol

positron emission

Positron emission involves a particle that has the same mass as an electron but a positive charge. The particle is released from the nucleus.
Positron

electron capture

Electron capture is when an unstable nucleus grabs an electron from its inner shell to help stabilize the nucleus. The electrons combine with a proton to form a neutron which stays in the nucleus.
Electron Capture