| − | '''Radioactivity''' is the emission of high [[energy]] [[particles]] through the natural phenomenon of the decay of unstable [[isotopes]] of [[chemical elements]] into more stable forms. | + | '''Radioactivity''' is the emission of high [[energy]] [[particles]] through the natural phenomenon of the decay of unstable [[isotopes]] of [[chemical elements]] into more stable forms. The most common types of radiation are called alpha, beta, and gamma radiation.<ref>http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html</ref> |