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 (see internal conversion) . History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom Internal conversion is a Radioactive decay process where an excited nucleus interacts with an Electron in one of the lower electron shells causing the The radionuclide, in this process, undergoes radioactive decay, and emits a gamma ray(s) and/or subatomic particles. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions A subatomic particle is an elementary or composite Particle smaller than an Atom. These particles constitute ionizing radiation. Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation Radionuclides may occur naturally, but can also be artificially produced.
Radionuclides are often referred to by chemists and physicists as radioactive isotopes or radioisotopes, and play an important part in the technologies that provide us with food, water and good health. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides However, they can also constitute real or perceived dangers.
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Origin
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. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 Half-Life (computer-game page here It's already listed in the disambiguation page 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. Environmental Radioactivity is the study of radioactive materials in the Human environment. Carbon-14, 14C, or radiocarbon, is a Radioactive isotope of Carbon discovered on February 27, 1940, by For the 1962 Bruce Conner film see Cosmic Ray (film Cosmic rays are energetic particles originating from space that impinge on
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. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The neutrons activate elements placed within the reactor. A typical product from a nuclear reactor is thallium-201 and Iridium-192. Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 The elements that have a large propensity to take up the neutrons in the reactor have a high Barnes Number.
- Particle accelerators such as cyclotrons accelerate particles to bombard a target to produce radionuclides. A cyclotron is a type of Particle accelerator. Cyclotrons accelerate Charged particles using a high- Frequency, alternating Voltage (potential Cyclotrons accelerate protons at a target to produce positron emitting radioisotopes e. g. fluorine-18. Fluorine-18 is a Fluorine radioisotope which is an important source of Positrons It has a mass of 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-99m generator used in nuclear medicine. Technetium-99m is a metastable Nuclear isomer of technetium-99 symbolized as 99mTc A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of Technetium Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy The parent produced in the reactor is molybdenum-99. There are 35 known isotopes of Molybdenum ( Mo) ranging in Atomic mass from 83 to 117 as well as four metastable Nuclear isomers Seven isotopes
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. Half-Life (computer-game page here It's already listed in the disambiguation page Synthetic isotopes are not naturally occurring on Earth, but they can be created by nuclear reactions. In Nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles
Uses
Radionuclides are used in two major ways: for their chemical properties and as sources of radiation. Radiation, as in Physics, is Energy in the form of waves or moving Subatomic particles emitted by an atom or other body as it changes from a higher energy 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. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 A radioactive tracer, also called a radioactive label, is a substance containing a Radioisotope (which is an isotope that has an unstable nucleus and that stabalizes One can then examine the result with a radiation detector, such as a geiger counter, to determine where the provided atoms ended up. A Geiger counter, also called a Geiger-Müller counter, is a type of Particle detector that measures Ionizing radiation. 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. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single
In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy 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. Single photon emission computed tomography (SPECT or less commonly SPET is a Nuclear medicine tomographic imaging technique using Gamma rays. Positron emission tomography ( PET) is a Nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the
Radioisotopes are also a promising method of treatment in hemopoietic forms of tumors, while the success for treatment of solid tumors has been limited so far. More powerful gamma sources sterilise syringes and other medical equipment. Sterilization (or sterilisation, see spelling differences) refers to any process that effectively kills or eliminates transmissible agents (such as Fungi About one in two people in Western countries are likely to experience the benefits of nuclear medicine in their lifetime. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy
In biochemistry and genetics, radionuclides label molecules and allow tracing chemical and physiological processes occurring in living organisms, such as DNA replication or amino acid transport. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is DNA replication is the process of copying a double-stranded DNA molecule to form two double-stranded molecules In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this
In food preservation, radiation is used to stop the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables. Food preservation is the process of treating and handling Food in a way that preserves its edibility and nutrition value
In agriculture and animal husbandry, radionuclides also play an important role. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture Animal husbandry, also called Animal science, stockbreeding or simple husbandry, is the agricultural practice of breeding They produce high intake of crops, disease and weather resistant varieties of crops, to study how fertilisers and insecticides work, and to improve the production and health of domestic animals.
Industrially, and in mining, radionuclides examine welds, to detect leaks, to study the rate of wear, erosion and corrosion of metals, and for on-stream analysis of a wide range of minerals and fuels. For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious" Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body
Most household smoke detectors contain the radionuclide americium formed in nuclear reactors, saving many lives. A smoke detector is a device that detects Smoke and issues an Alarm. Americium (ˌæməˈrɪsiəm is a Synthetic element that has the symbol Am and Atomic number 95 This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled
Radionuclides trace and analyze pollutants, to study the movement of surface water, and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers. Natural radionuclides are used in geology, archaeology, and paleontology to measure ages of rocks, minerals, and fossil materials. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Archaeology, archeology, or archæology (from Greek grc ἀρχαιολογία archaiologia – grc ἀρχαῖος archaīos Palaeontology redirects here For the Scientific journal, see Palaeontology (journal.
Dangers
If radionuclides are released into the environment, through accident, poor disposal, or other means, they can potentially cause harmful effects of radioactive contamination. Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment They can also cause damage if they are excessively used during treatment or in other ways applied to living beings. This is called radiation poisoning. Radiation poisoning, also called " radiation sickness " or a " creeping dose " is a form of damage to organ tissue due to excessive exposure to Radionuclides can also cause malfunction of electrical devices.
See also
References
- Carlsson J et al. This section covers Radionuclides hydrocarbures and organic solvents and information on the plants used for their remediation Radioactivity can be used in life sciences as a Radiolabel to easily visualise components or target molecules in a biological system Radiometric dating (often called radioactive dating) is a technique used to date materials usually based on a comparison between the observed abundance of a naturally occurring A radionuclide cisternogram is a Medical imaging study which involves injecting a Radionuclide by Lumbar puncture (spinal tap into a patient's Cerebral :"Tumour therapy with radionuclides: assessment of progress and problems". Radiotherapy and Oncology, Volume 66, Issue 2, February 2003, Pages 107–117. PMID 12648782. Available online as full text.
- Radioisotopes in Industry, World Nuclear Association.
External links
- PocketRad - A source for radioactive isotopes
- EPA - Radionuclides - EPA's Radiation Protection Program: Information.
- Interactive Chart of Nuclides - A chart of all nuclides
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