Cobalt-60 Nuclear Generating Station. The cobalt targets are substituted here for a small number of fuel assemblies. After entering a living mammal (such as a human being), some of the is excreted in feces. The remainder is taken up by tissues, mainly the liver, kidneys, and bones, where the prolonged exposure to gamma radiation can cause cancer. Over time, the absorbed cobalt is eliminated in urine. Cobalt is an element used to make steel. Uncontrolled disposal of in scrap metal is responsible for the radioactivity found in several iron-based products. In August 2012, Petco recalled several models of steel pet food
Chemical element hydrogen and deuterium). Thus, all carbon isotopes have nearly identical chemical properties because they all have six protons and six electrons, even though carbon atoms may, for example, have 6 or 8 neutrons. That is why the atomic number, rather than mass number or atomic weight, is considered the identifying characteristic of a chemical element. The symbol for atomic number is "Z". Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having "different" numbers of neutrons. Thus, for example, there are three main isotopes of carbon. All carbon atoms