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.
To understand radiocarbon dating, you first have to understand the word Although an element’s number of protons cannot change, the number of neutrons can vary slightly from each atom.
Atoms of the same element that have different numbers of neutrons are called isotopes. Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13.
Once an organism dies, it stops taking in carbon-14.
The carbon-14 it contained at the time of death decays over a long period of time, and the radioactivity of the material decreases.
However, once the organism dies, the amount of carbon-14 steadily decreases.
Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.It can be used on objects as old as about 62,000 years.Follow the links below to learn more about radiocarbon dating. Radiocarbon dating uses carbon isotopes A special kind of radiocarbon dating: Bomb radiocarbon dating What is an isotope?Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.