Radioactivity

Hi......Radioactivity ........  is the process of  emitting energy in the form of the waves or particles.
And radiation is generally produced when particles interact or decay.
A  large contribution of the radiation on earth is from the sun (solar)or from radioactive isotopes of the elements(terrestial).Isotope=unstable.......isotopes two or more of an element having  the same number of protons but different number of neutrons.Certain isotopes are  "unstable" and decay.
Alpha particles have a positive charge and it is a kind of decay that gives off  2 protons & 2 neutrons and becomes a Helium nucleus.
And beta particle is a kind if decay and it gives of positron and electron...and in turn makes it negatively charged...
Gamma rays do not have a charge and it is a high energy light particle and it is not visible of the EM spectrum.
The alpha particle is a Helium nucleus and it is the same as the element Helium.