Explore Related Concepts

Examples of Isotopes and Their Uses

In early twentieth century, Thomson’s plain cake model prompted Rutherford to replace it by Saturn model where he described the atom as consisting of a small central nucleus surrounded by electrons and rotating in rings. 
This view was supported by a study of the behaviour of a beam of alpha particles and directed on a thin gold metal foil. Since only small fraction of the alpha particles were recoiled and deflected and major of that particles went through without any obstacles proved that there is a large empty space in the atom.
The chemical behaviour of an atom is governed by its valence electrons or the ones which are spread across the empty space outside the nucleus. 
So basically the atoms that differ from one another only in their number of neutrons in nucleus display same chemical behaviour.

Such atoms were termed as isotopes and are denoted by same chemical symbol. 
The term isotope refers to the fact that different nuclides occupy same position in periodic table by virtue of same chemical properties was introduced in early twentieth century.

As the atomic mass was discussed and reported from the number of particles present in nucleus so even though the elements showed same chemical properties they showed distinct mass due to the fact that they have different number of neutrons.
The isotopes were now having a distinct definition on the offing and it went on to become the rule that elements showing same chemical properties, having same atomic number shows different mass number due to the number of neutrons present inside the nucleus.

Isotopic fractionation is the partitioning of isotopes by physical or chemical processes and is proportional to the differences in their masses. Physical isotopic fractionation processes are those in which diffusion rates are mass dependent, such as ultra-filteration or gaseous diffusion of ions or molecules.

Application of Isotopes:
Every isotope will have different set of properties and due to their difference in neutron number the physical properties do show a variation but the chemical properties remain same.
They also exhibit varied nuclear properties.

Spectroscopy: the unique nuclear properties of specific isotopes are used in the field of spectroscopy. 
Nuclear magnetic resonance spectroscopy could be used with isotopes showing non-zero nuclear spin and most common of these are 1Hydrogen, 2Deuterium, 13 Carbon, 15 Nitrogen and 31 Phosphorus.

Radio Isotopic Labelling: the isotope usage in isotopic labelling is very common and the unusual isotopes are used as markers and tracers in various chemical reactions. 
Usually the radiations of the radioactive isotopes are used for different reactants and chemical reaction rates.

Radiometric Dating: quite similar to radio-isotopic labelling these are also used for radiometric dating or simply radiocarbon dating. 
These are generally done by using isotopic tracers which are naturally occurring.

Isotopic Substitution: the determination of a reaction mechanism by using kinetic isotope effect may be carried out by isotopic substitution.

Isotopic Analysis: the relative abundance of an isotope in a given sample is carried out by determining the isotopic signature.

Isotope Bio-geochemistry helps in understanding the isotopical application of the constituents which are either water dissolving or present in gas phase. In solute isotope biochemistry research a series of isotopes used include isotopes of S, N and C, while a fewer use of Pb, U, Rn, He, Ra, Li and B are undertaken for these kind of research work. 
Quite opposite to the isotopes in water molecules, the solute isotope ratio could be signifcantly differed by the reaction of both biological and geological materials as water circulates in catchment.

Isotopic Hydrology would definitely looks into the application of the measurement of isotopes that would form molecules of water. 
The Oxygen isotopes O-16, O-17, and O-18 while the isotopes of H2 iinclude H-1, H-2 and H-3 make the suitable combinations wherever necessary. These isotopes are considered as the ideal tracers of the sources of water mainly because they constutute the water molecules. Water isotopes on occasion could be useful tracers of the path of water flow, especially where the groundwater systems are to be found and a distinctive water source composed of isotopes is formed. 

Low temperature environment leads to a stabilised H2 and O2 isotopes behave very conservatively. Any kind of interactions with O2 and H2 in the materials of Organic & geologic background the  concentration of these does not change as because the radioactive nature and decaying rate of half life. 
The main process that ddecides the composition of O2 and H2 isotopes of waters within the catchment (1) Ground surface water undergo phase change which affects it (2) ground surface simple mixing.

The application of environmental isotopes as hydrologic tracers in low temperatures system falls into two main categories. 
(a)    The tracers of the water itself which covers the water isotope hydrology
(b)    Tracers of the solutes in the water which again covers the solute isotope bio-geochemistry

These classification are by no means universal but they are conceptually useful and often eliminate confusion when these are compared to the results using different tracers. 

The field of isotopic geo-chemistry started taking its roots right after the advent of radio-activity. 
Huge number of the radioactive stabilised isotopes present in the periodic table occurring in the environment has helped in providing a huge wealth of information towards the unravelling of many secrets of the Earth system and its immediate environmental health. 
Due to the suitable geochemical and nuclear properties the isotopes help in tracing and also investigate a variety of topics with chronometers to carry out the studies of rocks and minerals, sea level changes and their reconstructions, paleo-climates, and paleo-environments, rock erosion and again the weathering rates of these rocks and minerals; in some cases material transport of various reservoirs of Earth and their magnetic processes.


Best Results From Wikipedia Yahoo Answers Encyclopedia Youtube

From Wikipedia

Isotopes of chlorine

Chlorine(Cl) has isotopes with mass numbers ranging from 32 g mol−1 to 40 g mol−1. There are two principal stable isotopes, 35Cl (75.76%) and 37Cl (24.24%), found in the relative proportions of 3:1 respectively, giving chlorine atoms in bulk an apparent atomic weight of 35.5.
Standard atomic mass: 35.453(2) u

Chlorine-36 (36Cl)

NO amounts of radioactive36.0Cl exist in the environment, in a ratio of about 7x10−13 to 1 with stable isotopes. 36Cl is produced in the atmosphere by spallation of 36Ar by interactions with cosmic rayprotons. In the subsurface environment, 36Cl is generated primarily as a result of neutron capture by 35Cl or muon capture by 40Ca. 36Cl decays to 36S and to 36Ar, with a combined half-life of 308,000 years. The half-life of this hydrophilic nonreactive isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years. Additionally, large amounts of 36Cl were produced by irradiation of seawater during atmospheric detonations of nuclear weapons between 1952 and 1958. The residence time of 36Cl in the atmosphere is about 1 week. Thus, as an event marker of 1950s water in soil and ground water, 36Cl is also useful for dating waters less than 50 years before the present. 36Cl has seen use in other areas of the geological sciences, forecasts, and elements.



A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits a gamma ray(s) and/or subatomic particles. These particles constitute ionizing radiation. Radionuclides may occur naturally, but can also be artificially produced.

The number of radionuclides is uncertain because the number of very short-lived radionuclides that have yet to be characterized is extremely large and potentially unquantifiable. Even the number of long-lived radionuclides is uncertain (to a smaller degree), because many "stable" nuclides are calculated to have half lives so long that their decay has not been experimentally measured. The nuclide list contain 90 nuclides that are theoretically stable, and 255 total stable nuclides that have not been observed to decay. In addition, there exist about 650 radionuclides that have been experimentally observed to decay, with half lives longer than 60 minutes (see list of nuclides for this list). Of these, about 339 are known from nature (they have been observed on Earth, and not as a consequence of man-made activities).

Including artificially produced nuclides, more than 3300 nuclides are known (including ~3000 radionuclides), including many more (> ~2400) that have decay half lives shorter than 60 minutes. This list expands as new radionuclides with very short half lives are characterized.

Radionuclides are often referred to by chemists and physicists, as radioactive isotopes or radioisotopes. Radioisotopes with suitable half lives play an important part in a number of constructive technologies (for example, nuclear medicine). However, radionuclides can also present both real and perceived dangers to health.


Naturally occurring radionuclides fall into three categories: primordial radionuclides, secondary radionuclides and cosmogenic radionuclides. Primordial radionuclides originate mainly from the interiors of stars and, like uranium and thorium, are still present because their half-lives are so long that they have not yet completely decayed. Secondary radionuclides are radiogenic isotopes derived from the decay of primordial radionuclides. They have shorter half-lives than primordial radionuclides. Cosmogenic isotopes, such as carbon-14, are present because they are continually being formed in the atmosphere due to cosmic rays.

Artificially produced radionuclides can be produced by nuclear reactors, particle accelerators or by radionuclide generators:

  • Radioisotopes produced with nuclear reactors exploit the high flux of neutrons present. The neutrons activate elements placed within the reactor. A typical product from a nuclear reactor is thallium-201 and iridium-192. The elements that have a large propensity to take up the neutrons in the reactor are said to have a high neutron cross-section.
  • Particle accelerators such as cyclotrons accelerate particles to bombard a target to produce radionuclides. Cyclotrons accelerate protons at a target to produce positron emitting radioisotopes e.g. fluorine-18.
  • Radionuclide generators contain a parent isotope that decays to produce a radioisotope. The parent is usually produced in a nuclear reactor. A typical example is the technetium-99mgenerator used in nuclear medicine. The parent produced in the reactor is molybdenum-99.
  • Radionuclides are produced as an unavoidable side effect of nuclear and thermonuclear explosions.

Trace radionuclides are those that occur in tiny amounts in nature either due to inherent rarity, or to half-lives that are significantly shorter than the age of the Earth. Synthetic isotopes are inherently not naturally occurring on Earth, but can be created by nuclear reactions.


Radionuclides are used in two major ways: for their chemical properties and as sources of radiation. Radionuclides of familiar elements such as carbon can serve as tracers because they are chemically very similar to the non-radioactive nuclides, so most chemical, biological, and ecological processes treat them in a near identical way. One can then examine the result with a radiation detector, such as a geiger counter, to determine where the provided atoms ended up. For example, one might culture plants in an environment in which the carbon dioxide contained radioactive carbon; then the parts of the plant that had laid down atmospheric carbon would be radioactive.

In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma rays or positrons can provide diagnostic information about a person's internal anatomy and the functioning of specific organs. This is used in some forms of tomography: single photon emission computed tomography and positron emission tomography scanning.

From Encyclopedia

radioactive isotope

radioactive isotope or radioisotope, natural or artificially created isotope of a chemical element having an unstable nucleus that decays, emitting alpha, beta, or gamma rays until stability is reached. The stable end product is a nonradioactive isotope of another element, i.e., radium-226 decays finally to lead-206. Very careful measurements show that many materials contain traces of radioactive isotopes. For a time it was thought that these materials were all members of the actinide series ; however, exacting radiochemical research has demonstrated that certain of the light elements also have naturally occurring isotopes that are radioactive. Since minute traces of radioactive isotopes can be sensitively detected by means of the Geiger counter and other methods, they have various uses in medical therapy, diagnosis, and research. In therapy, they are used to kill or inhibit specific malfunctioning cells. Radioactive phosphorus is used to treat abnormal cell proliferation, e.g., polycythemia (increase in red cells) and leukemia (increase in white cells). Radioactive iodine can be used in the diagnosis of thyroid function and in the treatment of hyperthyroidism. Since the iodine taken into the body concentrates in the thyroid gland, the radioaction can be confined to that organ. In research, radioactive isotopes as tracer agents make it possible to follow the action and reaction of organic and inorganic substances within the body, many of which could not be studied by any other means. They also help to ascertain the effects of radiation on the human organism (see radiation sickness ). In industry, radioactive isotopes are used for a number of purposes, including measuring the thickness of metal or plastic sheets by the amount of radiation they can stop, testing for corrosion or wear, and monitoring various processes.

From Yahoo Answers


Answers:Carbon-14: Archaeological dating Americium-241: Smoke detectors Cobalt-60: Food Irradiation Phosphorus-32: Biology study

Question:2. What effect do isotopes have in terms of the properties displayed by hydrogen?

Answers:An isotope is one of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass. For your example, hydrogen contains 1 proton inside the nucleus, and of course, 1 electron that orbits the nucleus. As in the definition, an isotope of hydrogen differs only in the number of neutrons it contains. Thus, an isotope of hydrogen can contain 1 neutron, 2 neutrons, etc. There are limits to containing a reasonable amount of extra neutrons, but that is another matter. Anyway, with hydrogen essentially containing an extra neutron, its atomic mass is altered about 1 amu. (Neutrons and protons way about 1 atomic mass unit (amu) each while electrons way almost nothing.) This makes the hydrogen atom considerably heavier. An addition to atomic mass, neutrons affect the atom's stability and nuclear properties. With too few or too much neutrons, nuclear properties become more severe, making the atom unstable and exposed to decay. This is due to the neutrons neutral charge opposed to the protons positive charge; both are located next to each other inside the nucleus. The separation of protons by neutrons affects the energy between adjacent protons. Hope this helps!!

Question:Can anyone give me any examples for isotopes used in: 1) Industry 2) Medical Can you also please say what they are, and what they are used for. Thanks so much :) :)

Answers:We have isotopes of cobalt(Co) used in the treatment of cancer.The isotopes of iodine are used to treat goitre. In matters of industry, Isotopes of hydrogen( protium -H1, deutirium H2 and tritium H3 ) are used to make hydrogen bombs by nuclear fusion method. Isotopes of uranium(Ur235 and Ur238 ) are used to make nuclear reactors. Isotopes of oxygen( O16 and O18 ) are also used in the industry


Answers:There are over 200 isotopes. Two of the most commonly used isotopes are C13 which is used for Carbon Dating and Deuterium which is H2. It is used as a tracer in environmental systems and is a result of nuclear bomb testing.

From Youtube

Rate of radioactive decay: A worked example to calculate the half life of an isotope :This worked example shows step by step, how to calculate the half life of an isotope. Calculating the half-life of a radioactive isotope has many applications not just in chemistry but in physics, environmental science and medicine. The worked example shows how easy it is to use the intergrated first order rate law in order to find the half life of an isotope...

Calculating Isotopic Abundance Example :The following video is on isotopes and calculating average atomic mass of various atoms. For more science and math podcasts search Papapodcasts in iTunes