Alpha particles consist of two
protons and two
neutrons bound together into a particle identical to a
helium nucleus. They are generally produced in the process of
alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the
Greek alphabet,
a. The symbol for the alpha particle is a or a
2+. Because they are identical to helium nuclei, they are also sometimes written as or indicating a helium ion with a +2 charge (missing its two electrons). If the
ion gains electrons from its environment, the alpha particle can be written as a normal (electrically neutral) helium atom .