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Alpha Beta Gamma Radiation


alpha particle Alpha Particles-

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 produced from large nuclei.

When an atom emits an alpha particle, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle. The atomic number of the atom goes down by exactly two, as a result of the loss of two protons – the atom becomes a new element. Examples of this are when uranium becomes thorium, or radium becomes radon gas due to alpha decay.

Alpha particles are commonly emitted by all of the larger radioactive nuclei such as uranium, thorium, actinium, and radium, as well as the transuranic elements. Unlike other types of decay, alpha decay as a process must have a minimum-size atomic nucleus which can support it. The smallest nuclei which have to date been found to be capable of alpha emission are the lightest nuclides of tellurium (element 52), with mass numbers between 106 and 110. The process of emitting an alpha sometimes leaves the nucleus in an excited state, with the emission of a gamma ray removing the excess energy.

example one


electron Beta Particles-

Beta emission is when a high speed electron (negative charge) leaves the nucleus. Beta emission occurs in elements with more neutrons than protons, so a neutron splits into a proton and an electron. The proton stays in the nucleus and the electron is emitted. 

example two

gamma ray symbolGamma Rays-

A nucleus which is in an excited state may emit one or more photons (packets of electromagnetic radiation) of discrete energies. The emission of gamma rays does not alter the number of protons or neutrons in the nucleus but instead has the effect of moving the nucleus from a higher to a lower energy state (unstable to stable). Gamma ray emission frequently follows beta decay, alpha decay, and other nuclear decay processes.



Positron emission involves a particle that has the same mass as an electron but a positive charge. The particle is released from the nucleus when a proton splits into a neutron and positive electron.


Separation of some radioactive emissions

Note the path of the beta particle is curved more than the alpha. This is due to the mass.

A wiffle ball can curve more than a more massive baseball.

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