History of Isotopes

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Isotopes are atoms of the same element with the same number of protons, but differing numbers of neutrons. Different isotopes of the same element have different masses. Because different isotopes have different numbers of neutrons, they do not all weigh the same or have the same mass. The word isotope, means “at the same place”, hence that isotopes are at the same place on the periodic table. In chemistry, if you want to refer to a certain isotope you must write it as such: AXZ. X represents the chemical symbol of the element, Z represents the atomic number, and A represents the mass number which is the number of protons and neutrons combined. For example if one were to refer to a hydrogen isotope, they would write it as 1H1 (ordinary hydrogen), 2H1 (deuterium-hydrogen isotope with one neutron), or 3H1 (tritium-isotope with two neutrons). Light elements usually have an equal amount of neutrons and protons; heavy elements need more neutrons than protons in order to stick together. Atoms with too many neutrons, or not enough, can exist for a while, but they will be unstable. Unstable atoms are radioactive. Their nuclei will change and decay by secreting radiation in the form of electromagnetic waves. Isotopes, radioisotopes in particular, have many uses. Some commonly used radioisotopes are Americum-241, Californium-252, Carbon-14, Colbalt-60, and Xenon-133. Americum-241 is used in many smoke detectors for homes and businesses. It is also used to measure levels of toxic lead in dried paint samples and to ensure thickness in rolling processes like steel and paper production. Californium-252 is used to inspect airline luggage for hidden explosives. Carbon-14 is used in biological research, agriculture, pollution control, and archeology. Cobalt-60 is used to sterilize surgical instruments and is also used in cancer treatment, food irradiation, and radiography.

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