A nuclear reaction differs to that of a chemical reaction. In chemical reactions, the nuclei of the atoms from the reactants to the products is unchanged. In nuclear reactions, the protons and neutrons are rearranged in the nucleus of the atom to form new elements. Radioactive substances give off three types of radiation; alpha particles, beta particles and gamma rays.


When the nucleus of an atom has too many protons it results in disequilibrium of the nucleus due to the excessive repulsion. In order to reduce the repulsion the atom emits an alpha particle. An alpha particle consists of 2 protons and 2 neutrons and is identical to a Helium nucleus. If an atom emits an alpha particle the atomic number is reduced by two and the molar mass by four.


When the neutron to proton ratio in the nucleus is too great a beta particle is emitted. In basic beta decay a neutron is transformed into a proton and an electron. The electron is then emitted as a beta particle which increases the atomic number by one and the molar mass is unchanged.


When the nucleus of an atom is at too high an energy it reaches equilibrium by emitting an electromagnetic photon of energy known as a gamma ray. The loss of a gamma ray does not alter the atomic number or the molar mass of the element, the atom simply passes to a lower state of energy.

|Example of decay series. |Contents page. |

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ANDREW SIDELL / June 2002 /