There are three common types of radiation.Alpha Radiation (α),Beta Radiation (β),Gamma Radiation (γ).
Alpha Radiation (α) is the emission of an alpha particle from an atom's nucleus.
An α particle contains two protons and two neutrons (and is similar to a He nucleus: ).
When an atom emits an a particle, the atom's atomic mass will decrease by four units (because two protons and two neutrons are lost) and the atomic number (z) will decrease by two units.
The element is said to "transmute" into another element that is two z units smaller.
An example of an a transmutation takes place when uranium decays into the element thorium (Th) by emitting an alpha particle.
The nuclei of atoms represented by their atomic numbers and mass numbers are called nucleides.
For example 92235U
Note: in nuclear chemistry, element symbols are traditionally preceded by their atomic weight (upper left) and atomic number (lower left).
Beta Radiation (β) is the transmutation of a neutron into a proton and a electron (followed by the emission of the electron from the atom's nucleus:).
When an atom emits a β particle, the atom's mass will not change (since there is no change in the total number of nuclear particles), however the atomic number will increase by one (because the neutron transmutated into an additional proton).
An example of this is the decay of the isotope of carbon named carbon-14 into the element nitrogen:
Gamma Radiation (γ) involves the emission of electromagnetic energy (similar to light energy) from an atom's nucleus.
No particles are emitted during gamma radiation, and thus gamma radiation does not itself cause the transmutation of atoms, however γ radiation is often emitted during, and simultaneous to, α or β radioactive decay.
X-rays, emitted during the beta decay of cobalt-60, are a common example of gamma radiation.