Radiocarbon dating of soils has always been a tricky problem. Since organic matter is continually being introduced into the soil, the measured age of soil organic matter has always tended to underestimate the true age of the soil. Carbon exists in the most part in the isotope C, but has a radioactive isotope, C, with a half-life of years. All terrestrial organisms use carbon dioxide in the atmosphere as a source of carbon, thus there is a constant exchange of C with the atmosphere. Since the rate of radioactive decay is proportional to the number of radioactive atoms present, it is unnecessary to measure the amount of C present in the soil sample.
Carbon dating problem examples, Review carbon 14 dating with this sample chemistry problem
How Carbon Dating Works | HowStuffWorks
Unstable nuclei decay. However, some nuclides decay faster than others. For example, radium and polonium, discovered by Marie and Pierre Curie, decay faster than uranium. That means they have shorter lifetimes, producing a greater rate of decay.
How Carbon-14 Dating Works
When we speak of the element Carbon, we most often refer to the most naturally abundant stable isotope 12 C. Although 12 C is definitely essential to life, its unstable sister isotope 14 C has become of extreme importance to the science world. Radiocarbon Dating is the process of determining the age of a sample by examining the amount of 14 C remaining against the known half-life, 5, years. The reason this process works is because when organisms are alive they are constantly replenishing their 14 C supply through respiration, providing them with a constant amount of the isotope.
About 75 years ago, Williard F. Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon, would be found to occur in nature. Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials. Working with several collaboraters, Libby established the natural occurrence of radiocarbon by detecting its radioactivity in methane from the Baltimore sewer.