Radioactive Decay
When an isotope is unstable it will decay by one of the following processes. Nuclear decay is a random and spontaneous process. If you observed an unstable nucleus it would not be possible to predict exactly when the nucleus would decay. The alpha, beta and gamma rays emitted by radiation are able to ionize atoms
| Type of decay | Alpha Decay | Negative Beta Decay | Positron Beta Decay | Gamma Ray |
| Description | An alpha particle is the same as a helium nucleus. The atom will emit the alpha particle, which will change the element. Alpha decay equations must be balanced. | An alpha particle is the same as a helium nucleus. The atom will emit the alpha particle, which will change the element. Alpha decay equations must be balanced. | In positron emission a proton changes into a neutron and positron. The positron is emitted along with a neutrino. | Gamma rays are high energy photons that are emitted during radioactive decay. If an isotope is still in an excited state after decay, it will emit a high energy photon to stabilize the energy. |
| Symbol | α, He²⁺, α²⁺ | β− | β | γ |
| Mass (atomic mass unit) | 4 | 1/2000 | 1/2000 | 0 |
| Speed comparatively | slow | fast | fast | very fast (speed of light) |
| Charge | +2 | -1 | +1 | 0 |
| Ionizing ability | high | medium | medium | 0 |
| Penetrating power | low | medium | medium | high |
| Can be stopped by | Paper | Aluminium | Aluminium | Lead |
