Isotopes have the same chemical properties, but different physical properties.An example of isotopes is carbon, which has three main isotopes, carbon-12, carbon-13 and carbon-14.There are two definitions of half-life, but they mean essentially the same thing.Half-life is the time taken for: Different radioactive isotopes have different half-lives.Sign up for Re Actions™, the e-newsletter for educators that offers teaching ideas about nuclear science and technology.It is published by the Center for Nuclear Science and Technology Information, an initiative of the American Nuclear Society, between September and May.The carbon-14 decays, with its half-life of 5,730 years, while the amount of carbon-12 remains constant in the sample.By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing.
Students use M&M’s (or pennies and puzzle pieces) to demonstrate the idea of radioactive decay.
For example, the half-life of carbon-14 is 5,715 years, but the half-life of francium-223 is just 20 minutes. It is possible to find out the half-life of a radioactive substance from a graph of the count rate against time.
The graph shows the decay curve for a radioactive substance.
It is a great introduction to the scientific process of deducing, forming scientific theories, and communicating with peers.
It is also useful in the mathematics classroom by the process of graphing the data.