Radiochemical dating uses
The periodic table of the elements assigns one place to every atomic number, and each of these places is labeled with the common name of the element, as, for example, calcium, radon, or uranium.
Not all the atoms of an element need have the same number of neutrons in their nuclei. Three nuclei with one proton are known that contain 0, 1, and 2 neutrons, respectively.
A form of radiometric dating used to determine the age of organic remains in ancient objects, such as archaeological specimens, on the basis of the half-life of carbon-14 and a comparison between the ratio of carbon-12 to carbon-14 in a sample of the remains to the known ratio in living organisms. A technique for measuring the age of organic remains based on the rate of decay of carbon 14.
The carbon 14 present in an organism at the time of its death decays at a steady rate, and so the age of the remains can be calculated from the amount of carbon 14 that is left. The cells of all living things contain carbon atoms that they take in from their environment.
The atomic mass is the sum of the protons and neutrons.
There are 82 stable elements and about 275 stable isotopes of these elements.
Uses of stable isotopes include the custom synthesis of new and complex labeled compounds to use in agriculture, biology, chemistry, drug testing, geology, health, nutrition, physics as well as diagnostic techniques in medicine.The total number of neutrons and protons (symbol A), or mass number, of the nucleus gives approximately the mass measured on the so-called atomic- mass-unit (amu) scale.The numerical difference between the actual measured mass of an isotope and A is called the mass defect.» View Examples of Stable Isotope Compounds Many of the chemical elements have a number of isotopes.The isotopes of an element have the same number of protons in their atoms (atomic number) but different masses due to different numbers of neutrons.