Answer:
See below.
Step-by-step explanation:
Radioactive isotopes are isotopes that are unstable; the nucleus decays spontaneously, giving off detectable particles and energy. An atom with a certain number of protons and neutrons is known as a nuclide. They can be either radioactive or stable. Carbon-12 is a stable carbon nuclide with six protons and six neutrons, whereas C-14 is a radioactive carbon nuclide with six protons and eight neutrons. C-14 is radioactive due to the extra two neutrons, whereas C-12 (and C-13, for that matter) is stable. Oh, and the fine point here is that the same nuclide can have different energy levels. As a result, barium-137 can exist in both a higher and lower energy state; they are distinct isotopes of the same nuclide. Consider a ball resting on top of a table - it might be on top of the table or on the floor just beneath the table. The ball is in the same area in both scenarios, but if it's on top of the table, it has a greater energy level; if it rolls off and falls to the floor, it loses that energy, just as Ba-137m will radioactively decay to Ba-137 (which is stable). OK, so this touches on what makes an atom radioactive in some way. If the nucleus has more energy than it needs, it will give it away by producing radiation. And the source of that extra energy is a mismatch between the amount of protons (which repel each other) and neutrons (which attract each other) (which tend to bind the nucleus together). The nucleus has excessive electrostatic repulsion if there are too few neutrons; if there are too many neutrons, the nucleus has excessive energy gluing it together. Protons become neutrons or neutrons become protons in beta decays; alpha decays remove two protons and two neutrons from the nucleus; in both situations, the nucleus is closer to the lowest-energy configuration that will survive. Oh, and in certain situations, when a radioactive atom decays to generate a non-radioactive one, the "daughter" atom will remain in an excited state for a brief period of time before giving up its energy by generating a gamma-ray photon. As a result, atoms become radioactive because they contain too much energy. So, depending on what they're employed for, certain atoms are radioactive... That's a vast issue, and I won't be able to get into it in depth here. However, here is a list of some of the applications:
- Cancer Treatment
- imaging for diagnosis (nuclear medicine)
- diagnosis of infectious diseases (radio-immune assay kits)
- Investigate biokinetics (where in the body do drugs or other compounds travel)
- dynamics of cells (where in the cell do specific molecules go)
- Sequencing of DNA (not as common today, but still used at times)
- causing mutations to investigate DNA damage and repair processes
- to examine genetic variability by introducing mutations\
- gauges for process control (thickness of glass, paper, steel, etc.)
- density and moisture content of the soil (for construction sites)
- Measurements of quality assurance
- metalworking (e.g. lead and metals analyzers)
- gauges for tank levels (over- and under-flow prevention)
- non-destructive evaluation (industrial radiography)