The half-life is the time required for half of the original sample of radioactive nuclei to decay.For example, if you start off with 1000 radioactive nuclei with a half-life of 10 days, you would have 500 left after 10 days; you would have 250 left after 20 days (2 half-lives); and so on.There are three carbon isotopes that occur as part of the Earth's natural processes; these are carbon-12, carbon-13 and carbon-14.The unstable nature of carbon 14 (with a precise half-life that makes it easy to measure) means it is ideal as an absolute dating method.
Some examples of the types of material that radiocarbon can determine the ages of are wood, charcoal, marine and freshwater shell, bone and antler, and peat and organic-bearing sediments.
Ever wondered how scientists know the age of old bones in an ancient site or how old a scrap of linen is?
The technique used is called carbon dating and in this lesson we will learn what this is and how it is used. Carbon dating, or radiocarbon dating, is a method used to date materials that once exchanged carbon dioxide with the atmosphere. In the late 1940s, an American physical chemist named Willard Libby first developed a method to measure radioactivity of carbon-14, a radioactive isotope.
This technique works well for materials up to around 50,000 years old.
Each radioactive isotope decays by a fixed amount, and this amount is called the half-life.