Example concept half life used radiometric dating
In other words, half (50%) of the Carbon-14 you started with has decayed into the daughter isotope Nitrogen-14.However, your readout from your radioactivity measuring instrument says you have only 25% Carbon-14 and 75% Nitrogen-14, so your fossil must have been through more than one half-life.Below is a chart of commonly used radiometric isotopes, their half-lives, and the daughter isotopes they decay into.Let's say you found a fossil you think to be a human skeleton.Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for the exponential decay equation.The accompanying table shows the reduction of a quantity as a function of the number of half-lives elapsed.Now it is time to put those math skills to good use.At one half-life, you would have approximately 50% Carbon-14 and 50% Nitrogen-14.
Now that you know how many half-lives have passed for your fossil, you need to multiply your number of half-lives by how many years are in one half-life. Your fossil is of an organism (maybe human) that died 11,460 years ago.Note the consequence of the law of large numbers: with more atoms, the overall decay is more regular and more predictable.A half-life usually describes the decay of discrete entities, such as radioactive atoms.One way that helps scientists place fossils into the correct era on the geologic time scale is by using radiometric dating.
Also called absolute dating, scientists use the decay of radioactive elements within the fossils or the rocks around the fossils to determine the age of the organism that was preserved.The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay.