By Kamil Erkan Libbys discovery, now known as the carbon-14 (or radiocarbon) technique, was a method that could be used to determine the age of organic remains.In the following years, archeologists used this technique extensively and determined exact dates for pre-historic settlements in the ancient world.Today, archeologists and paleontologists employ this technique to determine the age of organic materials (bones, teeth, wood, etc.) that are less than fifty thousand years in age. The theory is simple: Cosmic particles coming from outer space continuously collide with stable carbon-12 atoms in CO2 molecules, which are widespread in the atmosphere.Each carbon-12 atom takes up two neutrons and is converted into a radioactive carbon-14 atom.Over time there is a gradual decrease in the amount of Carbon-14 and the ratio of Carbon-14 atoms to other Carbon atoms declines. Therefore half of the Carbon-14 has decayed after 5730 years.Half of the remaining Carbon-14 then decays over the next 5730 years leaving one fourth of the original amount.Radioactive carbon-14 atoms rapidly mix and become uniform throughout the atmosphere.Deep oceans, the biosphere, and carbonate rocks are giant reservoirs of carbon and with the addition of the atmosphere they constitute the carbon cycle of the Earth.
By measuring the amount of carbon-14 left in dead organic material the approximate time since it died can be worked out.There's a small amount of radioactive carbon-14 in all living organisms.When they die no new carbon-14 is taken in by the dead organism.Easily modified for different abilities, with my low ability I made all the percentages either 75%, 50% or 25% to make it much easier for them. The worksheets can be used in a number of ways, I used them in two ways, I laminated them both in the same pouch front to back for them to use as a mini whiteboard and write directly on them with a whiteboard pen then rub out the ink for reuse for different questions and classes and to use as group work.Or, just print the graph for all pupils to use independently....What methods do they use and how do these methods work?In this article, we will examine the methods by which scientists use radioactivity to determine the age of objects, most notably carbon-14 dating.Carbon-14 dating is a way of determining the age of certain archeological artifacts of a biological origin up to about 50,000 years old.It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities.A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.How do scientists know how old an object or human remains are?