Radioactivity can be defined as a process by which unstable atomic nuclei undergoes transformation to produce stable or unstable nuclei with emission of radiations. The transformation of unstable nuclei into more stable nuclei or unstable nuclei with emission of radiation is known as radioactivity decay. In case the nuclei is transformed into another unstable nuclei, the daughter nuclei also undergoes another decay process until a stable nuclei is formed. Radioactivity decay may involve transformation of one element to another which is called transmutation or transformation of one isotope of an element to another. Radioactivity involves emission of energy from particles.
These radiations can be in form of alpha particles, which have a positive charge and are identical to helium nucleus or beta particles (positron), which have a negative charge and are identical to an electron or gamma rays which have no mass or charge. The gamma rays have the highest penetrating power and pose a greater danger while the alpha particles have the highest ionization power due to the high charge and the lowest penetration power. Radioactivity reactions can also be nuclear fission where a nucleus split when bombarded with neutrons releasing a lot of radiation energy. Examples of unstable isotopes include uranium 235 uranium 237 and uranium 234 which all disintegrate through a series of radioactivity decay processed into lead isotopes which are relatively stable (Knowledgerush, 2009).
Radioactivity decay has several applications such as dating of archeological and geological materials, production of nuclear energy in nuclear reactors, diagnosis and treatment of diseases and in various industrial and agricultural applications. Moreover, nuclear science has been used in development of nuclear weapons which has in several occasion been misused or caused havoc among nations in the world.
Radio activity and carbon dating
Scientists have had knowledge of radioactivity for over a century now. It was discovered by Henri Becquerel. He was a French scientist who was doing his research with phosphorescent materials who noted that his materials were glowing in the dark after they were exposed to light. However, he did not figure out immediately what was happening as he concluded that it was as a result of x-rays. Later, after several experiments, the idea of radioactivity was developed by scientists. It is therefore believed that Becquerel discovered radioactivity by accident. At first, scientists thought that the newly discovered radiation was similar to X-rays but more research was done which led to the discovery of alpha, beta and gamma radiations as well as radioactive isotopes. Since then, numerous advancements in the understanding and application of radioactivity have been achieved making it one of the most important scientific advancement (Lawson, 1999).
There are numerous sources of radiations of varying magnitude. The cosmos constantly receive radiations from the outer space in form of charged particles produced. These particles interact with the magnetic field of the earth and the atmosphere to produce radiations. These radiations are mainly beta and gamma. The doses of these radiations vary in different areas of the world due to varying magnetic fields. Moreover, radioactive materials which constantly undergo decay producing radiations are found everywhere in the universe. The decay products of uranium and thorium are located everywhere in both living and non living things. They are found in the food we eat, water and air. The bodies of living things are made up of elements such as carbon, lead and potassium with a percentage of radioactive isotopes of these elements. There are also a considerable amount of radiations the universe is exposed to as a result of manmade sources of radiations. This include modern health procedures in diagnosis and treatment of diseases using nuclear medicine and therapy, tobacco smoking and combustion of fuels and from detectors which use radiations such as smoke detectors and security detection systems in airports. Mining and use of nuclear fuel exposes people to high magnitudes of radiations. However, dosimeters have been developed to monitor the extent of exposure to radioactive radiations (Knowledgerush, 2009).
Carbon dating
Radiocarbon dating has been described as one of the scientific discoveries that have transformed the way scientists understand the universe. It is a technique that has been used in the approximation the ages of organic materials found in different archeological and geological sites around the world. The uncertainty of this technique is as result of the environmental effects as well as other errors related to the technique. The technique was developed in the mid 20th century and has been instrumental in the estimation of ages of geological and archeological materials. Carbon has three naturally occurring isotopes which are carbon 12, carbon 13 and carbon 14. Carbon 12 and carbon 13 are relatively stable while carbon 14 is unstable and thus show some radioactivity. The three isotopes of carbon occur in nature at equilibrium concentration with carbon 12 being the most abundant (98.89 percent) followed by carbon 13 (1.11 percent) and carbon 14 (0.0000000010 percent). Radiocarbon dating is based on the radioactivity decay of carbon 14 in the sample being analyzed.
In nature, the abundance of carbon 14 is constant due to the continued addition as the decay process continues. Carbon 14 is constantly added into nature though the bombardment of nitrogen 14 by cosmic rays from the space to produce carbon 14. Carbon 14 produced is oxidized by oxygen in the atmosphere very rapidly into carbon IV oxide. Some of the carbon 14 is dissolved in water which then precipitates as carbonates rocks. It also enters the food chain through photosynthesis where it gets its way into the plant tissues and finally is utilized by animals. Therefore, equilibrium is established with the concentration of carbon 14 and other carbon isotopes which is maintained all the time. As more carbon 14 enters the food chain or the atmosphere, the same amount is lost through radioactive decay. Therefore, the probability of a carbon 14 atom decaying in an isolated sample remains constant under all environmental conditions. Carbon 14 decays constantly and spontaneously with emission of beta particles and energy. The decay process is a reverse reaction of the formation of carbon 14 since it decays to form nitrogen 14. As soon as the living organism dies, the concentration equilibrium of carbon isotopes is affected. The rate of radioactive decay of carbon 14 continues while, there is no replenishment since the organism can no longer metabolize carbon 14. Therefore, the amount of carbon 14 remaining in a dead organism reduces exponentially with time (Riddle, 2007).
In the late 1940s, scientists were able to determine the half life of carbon 14 which enabled them to estimate the ages of archeological and geological samples. A half life of a radioactive isotope is the time taken for half the amount of the sample to reduce by half through radioactive decay. The half life of carbon is approximately 5568 years and therefore, after every 5568 years, the amount of carbon 14 in a fossil reduces by half the original amount. Therefore, if the amount of carbon 14 present in a residue can be determined, it is possible to determine the number of decay the sample has undergone when compared with the life levels of carbon 14 and thus determine when the sample died. Although the method has been limited to dating of samples of up to sixty thousand years, improvement in the technology has been of great importance where very low concentrations of carbon 14 which enables even older samples to be dated but with lower precision.
In the past, the ages of prehistoric materials were estimated based on the study of geology of the area. The depths of the sample give an estimate of the ages of the sample. However, carbon dating has transformed the dating of samples as well as being valuable in geology and earth science. However, it should be clear that carbon dating technique cannot be used to estimate the ages of rocks directly since they are not made up of organic materials. The age of the rock can rather be estimated by estimating the date when the organic material found surrounded by the rocks died. This means that the process is a reverse of previous technique where the rocks were used to determine the ages of organic materials found in them.
In the 1950s, even before carbon dating technique was proved to be accurate, it was used to estimate the ages of geological samples in moraines by estimating the age of the organic materials found in glacier deposits. Using this technique, geologists estimated that the maximum ice sheets were experienced eighteen thousands years ago. After the technique was proved to be accurate in dating of samples tens of thousands years old, it has been considered to be an instrumental method in Quaternary period studies among geologists. It has also been used in paleontology to estimate the age of living matters in different parts of the world. It was used to estimate the ages when mammoth became extinct in Europe and Siberia.
It is an invaluable method in the study of hydrology and oceanography among other earth sciences disciplines. The age of sediments found in the deep oceans and other large water bodies can be estimated using this technique by determining the age of calcite shells found in these sediments. The age of ground water can also be estimated by estimating the amount of carbon 14 atoms present in carbonates dissolved in the water. The amount of carbon 14 in carbon dioxide which geologists have found ensnared in ice cores can be used to estimate the atmospheric concentrations in different ages of the geological time scale (BBC home page, 2001).
These radiations can be in form of alpha particles, which have a positive charge and are identical to helium nucleus or beta particles (positron), which have a negative charge and are identical to an electron or gamma rays which have no mass or charge. The gamma rays have the highest penetrating power and pose a greater danger while the alpha particles have the highest ionization power due to the high charge and the lowest penetration power. Radioactivity reactions can also be nuclear fission where a nucleus split when bombarded with neutrons releasing a lot of radiation energy. Examples of unstable isotopes include uranium 235 uranium 237 and uranium 234 which all disintegrate through a series of radioactivity decay processed into lead isotopes which are relatively stable (Knowledgerush, 2009).
Radioactivity decay has several applications such as dating of archeological and geological materials, production of nuclear energy in nuclear reactors, diagnosis and treatment of diseases and in various industrial and agricultural applications. Moreover, nuclear science has been used in development of nuclear weapons which has in several occasion been misused or caused havoc among nations in the world.
Radio activity and carbon dating
Scientists have had knowledge of radioactivity for over a century now. It was discovered by Henri Becquerel. He was a French scientist who was doing his research with phosphorescent materials who noted that his materials were glowing in the dark after they were exposed to light. However, he did not figure out immediately what was happening as he concluded that it was as a result of x-rays. Later, after several experiments, the idea of radioactivity was developed by scientists. It is therefore believed that Becquerel discovered radioactivity by accident. At first, scientists thought that the newly discovered radiation was similar to X-rays but more research was done which led to the discovery of alpha, beta and gamma radiations as well as radioactive isotopes. Since then, numerous advancements in the understanding and application of radioactivity have been achieved making it one of the most important scientific advancement (Lawson, 1999).
There are numerous sources of radiations of varying magnitude. The cosmos constantly receive radiations from the outer space in form of charged particles produced. These particles interact with the magnetic field of the earth and the atmosphere to produce radiations. These radiations are mainly beta and gamma. The doses of these radiations vary in different areas of the world due to varying magnetic fields. Moreover, radioactive materials which constantly undergo decay producing radiations are found everywhere in the universe. The decay products of uranium and thorium are located everywhere in both living and non living things. They are found in the food we eat, water and air. The bodies of living things are made up of elements such as carbon, lead and potassium with a percentage of radioactive isotopes of these elements. There are also a considerable amount of radiations the universe is exposed to as a result of manmade sources of radiations. This include modern health procedures in diagnosis and treatment of diseases using nuclear medicine and therapy, tobacco smoking and combustion of fuels and from detectors which use radiations such as smoke detectors and security detection systems in airports. Mining and use of nuclear fuel exposes people to high magnitudes of radiations. However, dosimeters have been developed to monitor the extent of exposure to radioactive radiations (Knowledgerush, 2009).
Carbon dating
Radiocarbon dating has been described as one of the scientific discoveries that have transformed the way scientists understand the universe. It is a technique that has been used in the approximation the ages of organic materials found in different archeological and geological sites around the world. The uncertainty of this technique is as result of the environmental effects as well as other errors related to the technique. The technique was developed in the mid 20th century and has been instrumental in the estimation of ages of geological and archeological materials. Carbon has three naturally occurring isotopes which are carbon 12, carbon 13 and carbon 14. Carbon 12 and carbon 13 are relatively stable while carbon 14 is unstable and thus show some radioactivity. The three isotopes of carbon occur in nature at equilibrium concentration with carbon 12 being the most abundant (98.89 percent) followed by carbon 13 (1.11 percent) and carbon 14 (0.0000000010 percent). Radiocarbon dating is based on the radioactivity decay of carbon 14 in the sample being analyzed.
In nature, the abundance of carbon 14 is constant due to the continued addition as the decay process continues. Carbon 14 is constantly added into nature though the bombardment of nitrogen 14 by cosmic rays from the space to produce carbon 14. Carbon 14 produced is oxidized by oxygen in the atmosphere very rapidly into carbon IV oxide. Some of the carbon 14 is dissolved in water which then precipitates as carbonates rocks. It also enters the food chain through photosynthesis where it gets its way into the plant tissues and finally is utilized by animals. Therefore, equilibrium is established with the concentration of carbon 14 and other carbon isotopes which is maintained all the time. As more carbon 14 enters the food chain or the atmosphere, the same amount is lost through radioactive decay. Therefore, the probability of a carbon 14 atom decaying in an isolated sample remains constant under all environmental conditions. Carbon 14 decays constantly and spontaneously with emission of beta particles and energy. The decay process is a reverse reaction of the formation of carbon 14 since it decays to form nitrogen 14. As soon as the living organism dies, the concentration equilibrium of carbon isotopes is affected. The rate of radioactive decay of carbon 14 continues while, there is no replenishment since the organism can no longer metabolize carbon 14. Therefore, the amount of carbon 14 remaining in a dead organism reduces exponentially with time (Riddle, 2007).
In the late 1940s, scientists were able to determine the half life of carbon 14 which enabled them to estimate the ages of archeological and geological samples. A half life of a radioactive isotope is the time taken for half the amount of the sample to reduce by half through radioactive decay. The half life of carbon is approximately 5568 years and therefore, after every 5568 years, the amount of carbon 14 in a fossil reduces by half the original amount. Therefore, if the amount of carbon 14 present in a residue can be determined, it is possible to determine the number of decay the sample has undergone when compared with the life levels of carbon 14 and thus determine when the sample died. Although the method has been limited to dating of samples of up to sixty thousand years, improvement in the technology has been of great importance where very low concentrations of carbon 14 which enables even older samples to be dated but with lower precision.
In the past, the ages of prehistoric materials were estimated based on the study of geology of the area. The depths of the sample give an estimate of the ages of the sample. However, carbon dating has transformed the dating of samples as well as being valuable in geology and earth science. However, it should be clear that carbon dating technique cannot be used to estimate the ages of rocks directly since they are not made up of organic materials. The age of the rock can rather be estimated by estimating the date when the organic material found surrounded by the rocks died. This means that the process is a reverse of previous technique where the rocks were used to determine the ages of organic materials found in them.
In the 1950s, even before carbon dating technique was proved to be accurate, it was used to estimate the ages of geological samples in moraines by estimating the age of the organic materials found in glacier deposits. Using this technique, geologists estimated that the maximum ice sheets were experienced eighteen thousands years ago. After the technique was proved to be accurate in dating of samples tens of thousands years old, it has been considered to be an instrumental method in Quaternary period studies among geologists. It has also been used in paleontology to estimate the age of living matters in different parts of the world. It was used to estimate the ages when mammoth became extinct in Europe and Siberia.
It is an invaluable method in the study of hydrology and oceanography among other earth sciences disciplines. The age of sediments found in the deep oceans and other large water bodies can be estimated using this technique by determining the age of calcite shells found in these sediments. The age of ground water can also be estimated by estimating the amount of carbon 14 atoms present in carbonates dissolved in the water. The amount of carbon 14 in carbon dioxide which geologists have found ensnared in ice cores can be used to estimate the atmospheric concentrations in different ages of the geological time scale (BBC home page, 2001).
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