19-05-2014, 03:25 PM
Radioactive isotopes- boon or a bane
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Radioactivity is the spontaneous emission of energy from unstable atoms.
Atoms are found in all natural matter. There are stable atoms, which remain the same forever, and unstable atoms, which break down or 'decay' into new atoms. These unstable atoms are said to be 'radioactive', because they emit radioactivity from the nucleus as they decay.
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.
A few important uses of radio-isotopes (usually called radionuclides) are:
Radio-isotopes are widely used in medicine, as tracers that show up on X-ray film, and sometimes to destroy cancerous growths.
They are also used widely in industry. The radiation emitted by different radio-isotopes can be used for rapid, highly accurate measurement of material thickness, including the thickness of platings or coatings. The purity or composition of materials can be established by means of radio-isotopes. Radio-isotopes are used as gamma ray sources to irradiate and sterilize materials.
In agriculture, radio-isotope tracers can be used to check for proper distribution of insecticides.
Radio-isotopes are used to detect pipeline leaks, and to trace underground water.
Naturally occurring radio-isotopes can be detected in forensic science, to assist in solving crimes.
Naturally occurring radio-isotopes are also used by archaeologists and related specialists to help establish the authenticity and age of specimens.
Naturally occurring radio-isotopes are often used by geologists to establish the ages of rocks.
1. Diseases
o Many radioactive isotopes have been used in the diagnosis (detection) and treatment of diseases. The treatment of diseases by the use of radioisotopes is called "radiotherapy." The example given below shows one use of radioactive isotopes in the detection and treatment of diseases.
Radioactive Na-24 tracer, which emits γ-rays (gamma rays), has been used to detect the exact position of a tumor or blood clot in the human body. Radioactive Na-24 is injected into the body of the patient or administered orally. When the radioactive isotope moves in the body, it accumulates in the area of the tumor or blood clot. The exact position of the Na-24 is found with the help of a γ-ray detector, which indicates the location of the tumor or blood clot.
2. Industry
o Gamma rays emitting radioactive Co-60 have been used as a catalyst in the manufacture of ethyl bromide from ethylene and hydrogen bromide.
The carbon radioactive isotope C-15 has been used as a tracer in studying mechanisms involved in many industrial processes like alkylation, polymerization and catalytic synthesis.
Radioactive isotopes are used to determine the surface area of solids and the thickness of thin films and sheets of paper, steel and rubber.
Radioactive isotopes are used to test wear and tear inside a car engine.
Radioactive isotopes are used in detecting and preventing the corrosion of metals.
3. Agriculture
o Radioactive P-32 has been used to find the exact ratio between the amount of phosphorus taken up by a plant from the soil and the amount taken from added phosphate fertilizer. This is done by adding a quantity of radioactive P-32 (which is β-emitting) to phosphate fertilizer.
When the crops are exposed to γ-rays emitted by Co-60, the yield of crops is both quantitatively and qualitatively increased.
4. Insect Control
o To check the overgrowth of insect population, large numbers of male insects are exposed to radiation. The radiation makes them sterile, and hence they are be unable to produce new generations when they mate with their female counterparts, as the eggs will not develop. Malaria is brought under control by reducing the number of mosquitoes by this technique.