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.