Radioisotopes

adioisotopes: What Are They and How Are They Made?What are isotopes?The isotopes of an element are all the atoms that have in their nucleus the number of protons (atomic number) corresponding to the chemical behavior of that element. However, the isotopes of a single element vary in the number of neutrons in their nuclei. Since they still have the same number of protons, all these isotopes of an element have identical chemical behavior. But since they have different numbers of neutrons, these isotopes of the same element may have different radioactivity. An isotope that is radioactive is called a radioisotope or radionuclide. Two examples may help clarify this.The most stable isotope of uranium, U-238, has an atomic number of 92 (protons) and an atomic weight of 238 (92 protons plus 146 neutrons). The isotope of uranium of greatest importance in atomic bombs, U-235, though, has three fewer neutrons. Thus, it also has an atomic number of 92 (since the number of protons has not changed) but an atomic weight of 235 (92 protons plus only 143 neutrons). The chemical behavior of U-235 is identical to all other forms of uranium, but its nucleus is less stable, giving it higher radioactivity and greater susceptibility to the chain reactions that power both atomic bombs and nuclear fission reactors. Another example is iodine, an element essential for health; insufficient iodine in one 's diet can lead to a goiter. Iodine also is one of the earliest elements whose radioisotopes were used in what is now called nuclear medicine. The most common, stable form of iodine has an atomic number of 53 (protons) and an atomic weight of 127 (53 protons plus 74 neutrons). Because its nucleus has the "correct" number of neutrons, it is stable and is not radioactive. A less stable form of iodine also has 53 protons (this is what makes it behave chemically as iodine) but four extra neutrons, for a total atomic weight of 131 (53 protons and 78 neutrons). With "too many" neutrons in its

References: Barium-133 | 9694 TBq/Kg (262 Ci/g) | 10.7 years | 81.0, 356.0 | Cadmium-109 | 96200 TBq/Kg (2600 Ci/g) | 453 days | 88.0 | Cobalt-57 | 312280 TBq/Kg (8440 Ci/g) | 270 days | 122.1 | Cobalt-60 | 40700 TBq/Kg (1100 Ci/g) | 5.27 years | 1173.2, 1332.5 | Europium-152 | 6660 TBq/Kg (180 Ci/g) | 13.5 years | 121.8, 344.3, 1408.0 | Manganese-54 | 287120 TBq/Kg (7760 Ci/g) | 312 days | 834.8 | Sodium-22 | 237540 Tbq/Kg (6240 Ci/g) | 2.6 years | 511.0, 1274.5 | Zinc-65 | 304510 TBq/Kg (8230 Ci/g) | 244 days | 511.0, 1115.5 | Tritium (Hydrogen-3) | 357050 TBq/Kg (9650 Ci/g) | 12.32 years | 5.7 (average) | Alpha emission only Isotope | Activity | Half-life | Energies (KeV) | Polonium-210 | 166500 TBq/Kg (4500 Ci/g) | 138 days | 5304.5 | Isotope | Activity | Half-life | Radiation types | Energies (KeV) | Caesium-137 | 3256 TBq/Kg (88 Ci/g) | 30.1 years | Gamma & beta | G: 32, 661.6 B: 511.6, 1173.2 |