What are isotopes? now being used for many purposes?
Many of us may know that elements are made up of microscopic particles, known as atoms. Every atom has one core at the center, called a nucleus, around which electrons revolve in different orbits. Atom constitutes two particles-protons and neutrons.
What are isotopes?
Elements are made up of microscopic particles, known as atoms. Every atom has one core at the center, called a nucleus, around which electrons revolve in different orbits. Atom constitutes two particles-protons and neutrons. Atoms of a particular element have the same number of protons but can vary in neutrons. The number of protons in an atom is called the atomic number, of the element, whereas the total number of protons and neutrons in an atom is called the mass number or atomic weight of that element to which the atom belongs.
Atoms with the same number of protons but different numbers of neutrons are called isotopes. They have the same chemical nature/properties, as electrons revolving around the atom are the same but physical nature/properties can vary depending on mass, melting or boiling point, density, and freezing point of the element.
Isotopes are of two types, such as stable isotopes or nonradioactive isotopes and unstable isotopes or radioactive isotopes. Isotopes that don’t emit radiation are known as stable, whereas isotopes that emit radiation are called unstable. We may take the example of hydrogen having three isotopes. They are protium, deuterium, and tritium.
Protium/ hydrogen -1, has one proton, one electron, and zero neutrons, and deuterium has the same number of proton, electron, and one neutron. Tritium has one proton, one electron, and two neutrons. (2H) Deuterium and its compounds are used as nonradioactive or stable in chemical experiments. (3H)Tritium is also found in nature in small quantities and it is unstable or radioactive.
Silicon (14 Si) has 23 known isotopes, with the mass numbers raising from 22 to 44. The most common isotope is Si, and the most abundant isotope is 28 Si (92.23%), 29 Si (4.67%), and 30 Si (3.1%) are stable isotopes. 32 Si (silicon-28) is a stable isotope of Silicon, and the largest lived radioisotope is 32 Si.
The heaviest stable mono isotopic element is gold (197Au), which has one stable isotope 197Au, and 36 radioisotopes, with 195Au, being the most stable with a half-life of 186 days. Uranium -238, plutonium-238, plutonium-240. plutonium -241, and plutonium-242 are radioactive isotopes.
How isotopes are formed?
Isotopes are formed naturally through radioactive decay of the nucleus vide the emission of energy in the form of alpha particles, beta particles, etc. Examples of naturally occurring isotopes include isotopes of hydrogen-1H/ protium, 2H/deuterium, and 3H/tritium.
Carbon has 15 known isotopes from 6C to 22C of which 12C & 13C are stable, others are unstable and 14C is the longest-lived isotope, Uranium has 37 known isotopes including-234U, 235U, 238U, out of which 238U is more stable than other two isotopes. Titanium has also been released during nuclear weapons tests.
Further, it can be produced artificially in nuclear/ research reactors and accelerators by exposing a target substance to intense particles like neutrons or protons. It is called synthetic radioisotopes not produced in nature and have a short half-life. Most artificial isotopes have health hazards but have important applications in nuclear medicines and other industrial and research uses.
Examples of such isotopes include technetium-99,(produced during nuclear reactor operation) technetium-99m (a short-lived form of Tc-99), and promethium-146.
Uses of isotopes
Isotopes are used in many fields for their unique properties including medical research, diagnosis, and treatment of diseases, nuclear medicines, power generation, oil and gas exploration, national security, agriculture, carbon dating, space, migration of animals, birds and insects, basic research and real-life, etc.
- Nuclear medicine uses radioisotopes as tracers for diagnosis, to know the functioning of a specific organ for proper treatment. Technetium-99m (99m Tc) is a radioisotope that has been approved by the FDA for diagnostic imaging of different organs including the brain, bone, lungs, kidney, thyroid, heart, liver, bone marrow, and so on. Technetium-99m is taken orally or injected or inhaled into the body as required for the specific purpose. Approximately 40 million nuclear medicine procedures are followed all over the world every year.
- Iodine-131 is used for the treatment of tumors of the thyroid gland.
- In therapeutic applications in therapeutic applications of radioisotopes, specific cells are targeted to destroy, which is the basis of radiotherapy, commonly used in the treatment of cancer. Cesium-137 and Cobalt-60 both are also used to shrink the size of tumors in the body. In developed countries about one person in 50 uses diagnostic nuclear medicine each year.
- Radioisotopes are also used, to produce high-yield crop seeds for higher agricultural yield. It is further used to monitor the functions of fertilizers in different crops, fruit-bearing trees, plants, etc. Radiation from certain radioisotopes is used to kill harmful pests and insects to protect crops. Ionizing radiation is very useful for the preservation of agriculture and food products. Cobalt-60 is used to control the spoilage in stored grain pests.
- A fertilizer labeled with particular isotopes like nitrogen-15, or phosphors-32, provides a clue to determine the quantity of fertilizers taken by plants and how much of it got lost, for better fertilizer management.
- Energy can be produced in two ways in nuclear power plants- fission & fusion using radioactive isotopes. When nuclei of atoms split into several parts called fission and when nuclei fuse together forms fusion. Nuclear power reactors/ power plants are fueled with isotopes of uranium 235 for the generation of electrical energy. It is capable of sustaining a controlled nuclear chain reaction for the purpose called the fission process. In nuclear fusion isotopes of hydrogen-deuterium and tritium are used as fuel. In the process, two lighter atomic nuclei combine to form a heavier nucleolus, and the fusion reactor harvests the energy.
- Further, hydrogen-deuterium called heavy water used as a cooling agent in nuclear power plants.
- Radioisotope Power System (RPS) converts the heat energy ( heat generated by the natural decay of plutonium-238, a radioactive isotope) into electrical energy
Many countries are using nuclear reactors in satellite systems for the long lives of the satellites. The US in its first nuclear-powered space mission in 1961, sent the Transit IV-A satellite to space. On 29th June 2021, they celebrated the 60th anniversary of Transit IV-A’s launch. The satellite Radioisotope Power System(RPS) installed, converts heat(generated by the natural decay of plutonium-238 ) into electrical power making the satellite active.
In the defense sector, nuclear-powered submarines, ships, and nuclear weapons are now common.
Dr. Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate recently quoted saying that ” Nuclear power has opened the solar system to exploration, allowing us to observe and understand dark, distant planetary bodies that would otherwise be unreachable. And we’re just getting started.” which is very meaningful in further space research.
Radiocarbon dating (Carbon-14 dating), the method developed long back in 1940, is still an important tool for determining the age of an object containing organic material by using the properties of radiocarbon( a radioactive isotope of carbon).
Other important uses and applications of radioisotopes are in smoke detection. The technology is being used in the detection of flaws in steel sections for bridge and jet airliner constructions, to check the integrities of welds on pipes, tanks, jet engines, etc.
Study the migration of animals:
- Stable isotopes like deuterium isotope measurements are widely being used today to study the migration of many animals including bats, birds, insects, and fish. These stable isotopes are very useful for the evaluation of species diets, migration patterns in relation to climate change, habitation, land use pattern, etc.
- Ramananda Chakrabarti, Associate Professor at the Centre of Earth Sciences (CEaS) , Indian Institute of Science, Bangalore, India, and his team, published an article in Chemical Geology, recently where they claimed to find a way to map the oceanic temperature changes over millennia by probing tiny bone in the ears of fish called otoliths/otolites. Here they analyzed the ratio of different calcium isotopes in otoliths with Thermal Ionisation Mass Spectrometer (TINS) and measured the ratios of calcium isotopes in samples, and they were successful to correlate it with the seawater temperature, from which the fish were collected.
- Anthropologists use isotopic analysis to know the population movements, and their diets from chemical analysis of ancient human remain.
Geo isotopic mapping technology can provide vital information about the geographic origin of forensic evidence, and scientists are detecting the maps of the isotopic distribution of landscapes using the technology.
Isotopes of many elements are being used for the betterment of human civilization at the same time it is also being used for making weapons of mass destruction. Scientists and the head of the countries have to introspect and maintain constraints on weapons making and focus on utilizing the knowledge for better management of human and natural resources to drive away poverty, hunger, suffering, sorrows, pandemics, and so on.