We know that the modern periodic table is the tabular arrangement of all known elements according to their atomic number. The elements are arranged in increasing order of their atomic number from left to right. Do you have seen C-12 and C-14 in the periodic table? No! This is because C-12 and C-14 are different forms of same element with atomic number 6 that is carbon. Therefore there is only one position in the modern periodic table for this element. In other words we can say that C-12 and C-14 are different forms of same element with same atomic number but different mass number. Mass number is sum of number of protons and neutrons. Elements with same atomic number but different mass number indicate that they must have different number of neutrons.
For example, C-12 and C-14 have same atomic number that is 6 but number of neutrons is different that is 6 in C-12 and 8 in C-14. Such elements with same atomic number but different mass number are called as isotopes. Isotopes of same elements do not have different position in the periodic table as they have same atomic number.
Isotopes of same element have identical chemical behaviour, but with different atomic masses and physical properties. There can be more than one isotopes of one element. Since the chemical properties of an element depend on the number of protons or electrons that is same in isotopes therefore they show identical behaviour but physical properties may vary due to different mass number. Some of the isotopes are stable and some are unstable in nature.
In other words, stable isotopes do not undergo radioactive decay whereas unstable isotopes undergo radioactive decay. Unstable isotopes undergo spontaneous disintegration to stable isotopes with the emission radiations. Isotopes have various applications in different fields like agriculture, medical and chemical industries.
In chemistry, isotopes are different forms of same element with same atomic number and different mass number. Due to similar atomic number, they do not have separate position in periodic table. They can be stable or unstable. Unstable isotopes involve in radioactive decay and called as radioisotopes. Radioisotopes have several applications and widely used in different industries. They use in agriculture, biology, geology, health, nutrition, chemistry, drug testing, physics as well as diagnostic techniques in medicine.
Elements with atomic number 1 to 82 are stable in nature and have approx 275 isotopes. Unstable or radioisotopes are mainly formed from the decay of primordial uranium and thorium. Approx 3800 radioisotopes are known today.
There are several ways to produce radioisotopes like neutron activation in a nuclear reactor (capture of a neutron by the nucleus to form neutron rich atom), in cyclotron (introduction of protons to the nucleus to form proton rich atom) etc. Radioactive decay of radioisotopes emits alpha and/or beta particle or positron with energy in the form of electromagnetic radiation that is called as gamma rays.
Both radioisotopes and stable isotopes are widely used in medicine to diagnose and treat illnesses. Isotopes have extensive applications in bio-medical research and other fields like chemistry, physics, biology, and geo-sciences
There are many radioisotopes which are mainly used in the treatment of hazardous diseases such as cobalt-60 ( Co-60) is used to damage the cancer cells without surgery , that is known as radiotherapy. Skin cancer is treated with the help of beta rays from the P-32 and Sr-90. Gamma rays are also used in the sterilization of medical instruments like surgical equipment, syringes and bandages etc.
Small amount of Na-24 is injected into the patient to detect the tumors and blood clots. Similarly I-131 is used to investigate the thyroid glands and Plutonium-238 is used in nuclear batteries which are used to produce small electric shocks.
Like medical industries, radioisotopes and stable isotopes are also used in agriculture. They are used to cause mutation in insects that make them sterile or to cause death. This method helps in pest control in agriculture. Small amount of P-32 in phosphate fertilizers is able to detect the metabolism of phosphorus by plants.
The emitted radiations by radioisotope can be detected with the help of Geiger-Miller counter that can be traced the passage of phosphate ions in plants. C-14 is mainly used to study the passage of carbon in plants during photosynthesis.
We can observe uses of isotopes in daily life and also in several industries such as Na-24 is used to detect the leakage of underground pipes whereas beta rays help to control the thickness of plastic, paper and metal sheets in respective industries. The level of filled bottles or cans can be detected with the help of gamma rays. On the other hand, Na-24 is used to measure the wear out rate of engine in a vehicle. Co-60 helps in food preservation.
It kills bacteria in food to make fresh vegetables and fruits last longer but do not change quality, flavor and texture of food. Exposure with gamma rays inhibits the budding in potatoes that helps the preservation of potatoes for long time. C-14 is widely used in estimation of the age of ancient artifacts by radiocarbon dating method. Nuclear energy is one of the bet alternate for future energy production that comes from nuclear fission and fusion of radioisotopes like Plutonium, Thorium etc. Radioisotopes are also used in smoke detectors and to detect flaws in steel sections which are used for bridge and jet airliner construction. Some other uses of isotopes are listed below.
- Check the integrities of welds on pipes, tanks, jet engines
- Used to gauge thickness of paper and plastic
- Control the density of mixtures
- To assess the degree of filling of cans and bottles
- To sterilize contact lens cleaning solution, cosmetics, medical instruments
- To scan luggage to detect explosives or weapons
- To detect lead in paint