Radioactivity, also known as radioactive decay, is a process by which a radioactive isotope loses subatomic particles (helium nuclei or electrons) from its nucleus along with usual emission of gamma radiation, and becomes a different element.In a large collection of atoms, there is a definite time, called the half-life of the isotope, after which one-half of the total number of nuclei would have decayed.Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source (rā'dē-ō-mět'rĭk) A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.For inorganic materials, such as rocks containing the radioactive isotope rubidium, the amount of the isotope in the object is compared to the amount of the isotope's decay products (in this case strontium).The carbon-14 it contained at the time of death decays over a long period of time.By measuring the amount of carbon-14 left in dead organic material the approximate time since it died can be worked out.His work has been published online and in various newspapers, including "The Cornish Times" and "The Sunday Independent." Grahams specializes in technology and communications.He holds a Bachelor of Science, postgraduate diplomas in journalism and website design and is studying for an MBA.
Later called Ötzi the Iceman, small samples from his body were carbon dated by scientists.The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out. Chronometric dating, also known as chronometry or absolute dating, is any archaeological dating method that gives a result in calendar years before the present time.Scientists first developed absolute dating techniques at the end of the 19th century.Before this, archaeologists and scientists relied on deductive dating methods, such as comparing rock strata formations in different regions.