43 molybdenum ← technetium → ruthenium Mn ↑ Tc ↓ Re Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	technetium, Tc, 43
Chemical series	transition metals
Group, Period, Block	7, 5, d
Appearance	silvery gray metal
Standard atomic weight	[98](0)  g·mol−1
Electron configuration	[Kr] 4d5 5s2
Electrons per shell	2, 8, 18, 13, 2
Physical properties
Phase	solid
Density (near r.t.)	11  g·cm−3
Melting point	2430 K (2157 °C, 3915 °F)
Boiling point	4538 K (4265 °C, 7709 °F)
Heat of fusion	33. Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Rhenium (ˈriːniəm is a Chemical element with the symbol Re and Atomic number 75 This is a typical display of the periodic table of the elements and contains the symbol and Atomic number of each element Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of chemical elements by symbol, including the A table of Chemical elements ordered by Atomic number and color coded according to type of element In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In Chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings It commonly refers to any element in In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In the Periodic table of the elements, a period is a horizontal row of the table A block of the Periodic table of elements is a set of adjacent groups The respective highest-energy electrons in each element in a block belong to the same Atomic See also A period 5 element is one of the Chemical elements in the fifth row (or period) of the periodic table of the elements. The d-block of the periodic table of the elements consists of those Periodic table groups that contain elements in which in the atomic ground state the highest-energy The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass To help compare different orders of magnitude, the following list describes various Mass levels between 10&minus36&thinsp kg and 1053&thinspkg In Atomic physics and Quantum chemistry, electron configuration is the arrangement of Electrons in an Atom, Molecule, or other Krypton (ˈkrɪptən or /ˈkrɪptɒn/ from kryptos "hidden" is a Chemical element with the symbol Kr and Atomic number 36 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron shell may be crudely thought of as an Orbit followed by Electrons around an Atom nucleus. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The standard Enthalpy of fusion (symbol \Delta{}H_{fus} also known as the heat of fusion or specific melting heat, is the amount of 29  kJ·mol−1
Heat of vaporization	585. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material The enthalpy of vaporization, (symbol \Delta{}_{v}H also known as the heat of vaporization or heat of evaporation, is the Energy required 2  kJ·mol−1
Specific heat capacity	(25 °C) 24. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity 27  J·mol−1·K−1
Vapor pressure (extrapolated) P(Pa) 1 10 100 1 k 10 k 100 k at T(K) 2727 2998 3324 3726 4234 4894
Atomic properties
Crystal structure	hexagonal
Oxidation states	7, 6, 5,[1] 4,[2] 3,[3] 1[4] (strongly acidic oxide)
Electronegativity	1. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons 9 (Pauling scale)
Electron affinity	-53 kJ/mol
Ionization energies	1st: 702 kJ/mol
	2nd: 1470 kJ/mol
	3rd: 2850 kJ/mol
Atomic radius	135  pm
Atomic radius (calc. The electron affinity, E ea of an Atom or Molecule is the energy required to detach an electron from a singly charged negative The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Atomic radius, and more generally the size of an atom, is not a precisely defined Physical quantity, nor is it constant in all circumstances A picometre ( American spelling: picometer, symbol pm) is a unit of Length in the Metric system, equal to one trillionth )	183  pm
Covalent radius	156  pm
Miscellaneous
Magnetic ordering	Paramagnetic
Thermal conductivity	(300 K) 50. The covalent radius, r cov is a measure of the size of Atom which forms part of a Covalent bond. In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. 6  W·m−1·K−1
CAS registry number	7440-26-8
Selected isotopes
Main article: Isotopes of technetium iso NA half-life DM DE (MeV) DP 95mTc syn 61 d ε - 95Mo γ 0. CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Technetium ( Tc) is one of the two elements in the first 82 that have no stable Isotopes (in fact it is the lowest-numbered element that is exclusively radioactive Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet Half-Life (computer-game page here It's already listed in the disambiguation page Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The decay energy is the Energy released by a Nuclear decay. The energy difference of the Reactants is often written as Q: where Q In Nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a Nuclide A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in To help compare Orders of magnitude of different times this page lists times between 106 seconds and 107 seconds (approximately 11 A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions 204, 0. 582, 0. 835 - IT 0. Internal conversion is a Radioactive decay process where an excited nucleus interacts with an Electron in one of the lower electron shells causing the 0389, e 95Tc 96Tc syn 4.3 d ε - 96Mo γ 0. A conversion electron is a term used to describe an Electron which results from the Internal conversion process A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in To help compare Orders of magnitude of different Times this page lists times between 105 seconds and 106 seconds (approximately 27 Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo 778, 0. 849, 0. 812 - 97Tc syn 2.6×106 y ε - 97Mo 97mTc syn 90 d IT 0. A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in To help compare Orders of magnitude of different times this page lists times between 320 000 Years and 3 200 000 years (1013 Seconds and 1014 seconds A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in To help compare Orders of magnitude of different times this page lists times between 106 seconds and 107 seconds (approximately 11 965, e 97Tc 98Tc syn 4.2×106 y β- 0. A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in To help compare Orders of magnitude of different times this page lists times between 3 In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted 4 98Ru γ 0. Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 745, 0. 652 - 99Tc trace 2.111×105 y β- 0. A trace radioisotope is a Radioisotope that occurs naturally in trace amounts (i To help compare Orders of magnitude of different times this page lists times between 32 000 Years and 320 000 years (1012 Seconds mdasha terasecond 294 99Ru 99mTc trace 6.01 h IT 0. Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies A trace radioisotope is a Radioisotope that occurs naturally in trace amounts (i To help compare Orders of magnitude of different Times this page lists times between 104 seconds and 105 seconds (approximately 2 The hour (symbol h) is a unit of Time. It is not an SI unit but is accepted for use with the SI 142, 0. 002 99Tc γ 0. 140 -
References

Technetium (pronounced /tɛkˈniːʃɪəm/) is the lightest chemical element with no stable isotope. Recommended values for many properties of the elements together with various references are collected on these data pages A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Stable isotopes are chemical isotopes that are not Radioactive (to current knowledge It is a synthetic element. In chemistry the Chemical elements labeled as synthetic are too unstable to be found naturally on Earth. It has atomic number 43 and is given the symbol Tc. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton The chemical properties of this silvery grey, crystalline transition metal are intermediate between rhenium and manganese. In Chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings It commonly refers to any element in Rhenium (ˈriːniəm is a Chemical element with the symbol Re and Atomic number 75 Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Its short-lived gamma-emitting nuclear isomer ^99mTc (technetium-99m) is used in nuclear medicine for a wide variety of diagnostic tests. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies Technetium-99m is a metastable Nuclear isomer of technetium-99 symbolized as 99mTc Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy ⁹⁹Tc is used as a gamma ray-free source of beta particles. Technetium-99 (99Tc is an isotope of Technetium which decays with a Half-life of 211000 years emitting soft beta rays but no gamma rays and has a Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Beta particles are high-energy high-speed Electrons or Positrons emitted by certain types of Radioactive nuclei such as Potassium -40 The pertechnetate ion (TcO₄^-) has been suggested as a strong anodic corrosion inhibitor for mild steel in closed cooling systems. The pertechnetate ( technetate(VII) ion is an Oxoanion with the chemical formula TcO4&minus An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0

Before the element was discovered, many of the properties of element 43 were predicted by Dmitri Mendeleev. Professor Dmitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties which appeared with some regularity as he laid out the elements Dmitri Ivanovich Mendeleev (sometimes spelled Mendeleyev; Дми́трий Ива́нович Менделе́ев) ( &ndash) was a Russian chemist and Mendeleev noted a gap in his periodic table and called the element ekamanganese(Em). The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is In 1937 its isotope ⁹⁷Tc became the first predominantly artificial element to be produced, hence its name (from the Greek τεχνητός, meaning "artificial"). Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Most technetium produced on Earth is a by-product of fission of uranium-235 in nuclear reactors and is extracted from nuclear fuel rods. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may Uranium-235 is an isotope of uranium that differs from the element's other common isotope Uranium-238, by its ability to cause a rapidly expanding fission This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages No isotope of technetium has a half-life longer than 4. Half-Life (computer-game page here It's already listed in the disambiguation page 2 million years (⁹⁸Tc), so its detection in red giants in 1952 helped bolster the theory that stars can produce heavier elements. A red giant is a luminous Giant star of low or intermediate mass (roughly 0 On Earth, technetium occurs in trace but measurable quantities as a product of spontaneous fission in uranium ore or by neutron capture in molybdenum ores. Spontaneous fission (SF is a form of Radioactive decay characteristic of very heavy Isotopes and is theoretically possible for any atomic nucleus whose mass is greater Neutron capture is a kind of Nuclear reaction in which an Atomic nucleus collides with one or more Neutrons and they merge to form a heavier nucleus Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo

Contents 1 Characteristics 2 Applications 2.1 Nuclear medicine 2.2 Industrial/Chemical 3 History 3.1 Search for element 43 3.2 Official discovery and later history 4 Occurrence and production 4.1 Byproduct production of Tc-99 in fission wastes 4.2 Neutron activation of molybdenum or other pure elements 5 Isotopes 5.1 Stability of technetium isotopes 6 References 6.1 Works cited 6.2 Notes 7 External links

Characteristics

Technetium is a silvery-grey radioactive metal with an appearance similar to platinum. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 However, it is commonly obtained as a grey powder. Its position in the periodic table is between rhenium and manganese and as predicted by the periodic law its properties are intermediate between those two elements. Rhenium (ˈriːniəm is a Chemical element with the symbol Re and Atomic number 75 Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. The Periodic table is a tabular method of displaying the chemical elements Technetium is unusual among the lighter elements in that it has no stable isotopes. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Only technetium and promethium have no stable isotopes, but are followed by elements which do. Promethium (prəˈmiːθiəm/ /proʊˈmiːθiəm is a Chemical element with the symbol Pm and Atomic number 61

Technetium is therefore extremely rare on Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Technetium plays no natural biological role and is not normally found in the human body. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus

The metal form of technetium slowly tarnishes in moist air. Tarnish is a layer of Corrosion that develops over Copper, Brass, Silver, Aluminum as well as a degree of semi-reactive metals as Its oxides are TcO₂ and Tc₂O₇. An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Under oxidizing conditions technetium (VII) will exist as the pertechnetate ion, TcO₄^-. The pertechnetate ( technetate(VII) ion is an Oxoanion with the chemical formula TcO4&minus An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge ^[5] Common oxidation states of technetium include 0, +2, +4, +5, +6 and +7. The oxidation number of a central atom in a coordination compound is the charge that it would have if all the Ligands were removed along with the Electron pairs ^[6] Technetium will burn in oxygen when in powder form. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the ^[7] It dissolves in aqua regia, nitric acid, and concentrated sulfuric acid, but it is not soluble in hydrochloric acid. Aqua regia ( Latin for royal water) is a highly corrosive fuming yellow or red solution Nitric acid ( H[[nitrate NO3]] also known as Aqua fortis and spirit of nitre, is a highly corrosive and Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Hydrochloric acid is the Solution of Hydrogen chloride ( H[[Chlorine Cl]] in water It has characteristic spectral lines at 363 nm, 403 nm, 410 nm, 426 nm, 430 nm, and 485 nm. A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range compared A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a ^[8]

The metal form is slightly paramagnetic, meaning its magnetic dipoles align with external magnetic fields even though technetium is not normally magnetic. Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges ^[9] The crystal structure of the metal is hexagonal close-packed. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. Regular hexagon The internal Angles of a regular hexagon (one where all sides and all angles are equal are all 120 ° and the hexagon has 720 degrees Pure metallic single-crystal technetium becomes a type II superconductor at 7. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance 46 K; irregular crystals and trace impurities raise this temperature to 11. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 2 K for 99. 9% pure technetium powder. ^[10] Below this temperature technetium has a very high magnetic penetration depth, the largest among the elements apart from niobium. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance Niobium (naɪˈoʊbiəm or columbium (/kəˈlʌmbiəm/ is a Chemical element that has the symbol Nb and Atomic number 41 ^[11]

Technetium is produced in quantity by nuclear fission, and spreads more readily than many radionuclides. In spite of the importance of understanding its toxicity in animals and humans, experimental evidence is scant. It appears to have low chemical toxicity. Its radiological toxicity (per unit of mass) is a function of compound, type of radiation for the isotope in question, and the isotope half-life. Technetium-99m is particularly attractive for medical applications, as the radiation from this isotope is a gamma ray with the same wavelength as X-rays used for common medical diagnostic X-ray applications, giving it adequate penetration while causing minimal damage for a gamma photon. Technetium-99m is a metastable Nuclear isomer of technetium-99 symbolized as 99mTc This, plus the extremely short half-life of this metastable nuclear isomer, followed by the relatively long half-life of the daughter isotope Tc-99 which allows it to be eliminated from the body before it decays. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies This leads to a relatively low dose of administered radiation in biologically dose-equivalent amounts (sieverts) for a typical Tc-99m based nuclear scan (see more on this subject below). The sievert (symbol Sv is the SI derived unit of dose equivalent. ^[10]

All isotopes of technetium must be handled carefully. The most common isotope, technetium-99, is a weak beta emitter; such radiation is stopped by the walls of laboratory glassware. Soft X-rays are emitted when the beta particles are stopped, but as long as the body is kept more than 30 cm away these should pose no problem. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. The primary hazard when working with technetium is inhalation of dust; such radioactive contamination in the lungs can pose a significant cancer risk. Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment For most work, careful handling in a fume hood is sufficient; a glove box is not needed. A fume hood or fume cupboard is a large piece of Scientific equipment common to Chemistry laboratories designed to limit a person's exposure to hazardous A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects while being in a different atmosphere from the object ^[10]

Applications

Nuclear medicine

^99mTc ("m" indicates that this is a metastable nuclear isomer) is used in radioactive isotope medical tests, for example as a radioactive tracer that medical equipment can detect in the human body. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy 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 ^[12] It is well suited to the role because it emits readily detectable 140 keV gamma rays, and its half-life is 6. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions 01 hours (meaning that about seven eighths of it decays to ⁹⁹Tc in 24 hours). ^[13] Klaus Schwochau's book Technetium lists 31 radiopharmaceuticals based on ^99mTc for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors. Radiopharmacology is the study and preparation of radiopharmaceuticals, which are radioactive Pharmaceuticals Radiopharmaceuticals are used in the field The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain Myocardium is the muscular tissue of the Heart. Relationship to other layers The other tissues of the heart are the Endocardium The thyroid is one of the largest Endocrine glands in the body lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive The liver is a vital organ in the human body and is present in Vertebrates and some other animals The gallbladder (or cholecyst sometimes gall bladder is a small organ whose function in the body is to store Bile and aid in the digestive process The kidneys are complicated organs that have numerous biological roles In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products See also Cancer A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells (termed neoplastic ^[10]

Immunoscintigraphy incorporates ^99mTc into a monoclonal antibody, an immune system protein capable of binding to cancer cells. Immunoscintigraphy is a commonly used procedure to find cancer cells in the body by injecting a radioactive compound which binds to cancer cells and then scanning for concentrations of Monoclonal antibodies ( mAb or moAb) are monospecific antibodies that are identical because they are produced by one type of immune cell An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled A few hours after injection, medical equipment is used to detect the gamma rays emitted by the ^99mTc; higher concentrations indicate where the tumor is. This technique is particularly useful for detecting hard-to-find cancers, such as those affecting the intestine. In Anatomy, the intestine is the segment of the alimentary canal extending from the Stomach to the Anus and in humans and other mammals consists These modified antibodies are sold by the German company Hoechst (now part of Sanofi-Aventis) under the name "Scintium". Hoechst AG was a German chemicals then life-sciences company that became Aventis after its merger with Rhône-Poulenc S Sanofi-Aventis () headquartered in Paris, France, is a multinational pharmaceutical company ^[14]

When ^99mTc is combined with a tin compound it binds to red blood cells and can therefore be used to map circulatory system disorders. Tin is a Chemical element with the symbol Sn (stannum and Atomic number 50 Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood This is an article about the rock music band "Circulatory System" It is commonly used to detect gastrointestinal bleeding sites. A pyrophosphate ion with ^99mTc adheres to calcium deposits in damaged heart muscle, making it useful to gauge damage after a heart attack. A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply ^[15] The sulfur colloid of ^99mTc is scavenged by the spleen, making it possible to image the structure of the spleen. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 The spleen is an organ found in all Vertebrate animals In humans the spleen is located in the abdomen of the body where it functions in the destruction of redundant Red ^[16]

Radiation exposure due to diagnostic treatment involving Tc-99m can be kept low. Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment Because ^99mTc has a short half-life and high energy gamma (allowing small amounts to be easily detected), its quick decay into the far-less radioactive ⁹⁹Tc results in relatively less total radiation dose to the patient, per unit of initial activity after administration. In the form administered in these medical tests (usually pertechnetate) both isotopes are quickly eliminated from the body, generally within a few days. ^[15]

Technetium for nuclear medicine purposes is usually extracted from technetium-99m generators. A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of Technetium ^95mTc, with a half-life of 61 days, is used as a radioactive tracer to study the movement of technetium in the environment and in plant and animal systems. 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 ^[10]

Industrial/Chemical

Technetium-99 decays almost entirely by beta decay, emitting beta particles with consistent low energies and no accompanying gamma rays. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Moreover, its long half-life means that this emission decreases very slowly with time. It can also be extracted to a high chemical and isotopic purity from radioactive waste. For these reasons, it is a NIST standard beta emitter, used for equipment calibration. ^[10]

Technetium-99 has also been proposed for use in optoelectric and nanoscale nuclear batteries. Nanotechnology, sometimes shortened to nanotech, refers to a field of Applied science whose theme is the control of matter on an Atomic and Molecular The terms atomic battery, nuclear battery, tritium battery and radioisotope battery are used to describe a device which uses the emissions from a Radioactive ^[17]

Like rhenium and palladium, technetium can serve as a catalyst. Rhenium (ˈriːniəm is a Chemical element with the symbol Re and Atomic number 75 Palladium (pronounced \pəˈleɪdiəm\ is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the For certain reactions, for example the dehydrogenation of isopropyl alcohol, it is a far more effective catalyst than either rhenium or palladium. Dehydrogenation is a chemical reaction that involves the elimination of Hydrogen (H2 Isopropyl alcohol (also isopropanol, iso, isopro, Rubbing alcohol, or the abbreviation IPA) is a common name for Of course, its radioactivity is a major problem in finding safe applications. ^[10]

Under certain circumstances, a small concentration (5×10⁻⁵ mol/L) of the pertechnetate ion in water can protect iron and carbon steels from corrosion. The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this The litre or liter (see spelling differences) is a unit of Volume. For this reason, pertechnetate has been suggested as a possible anodic corrosion inhibitor for steel, although technetium's radioactivity poses problems for strictly chemical uses such as these. Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 While (for example) CrO₄²⁻ can also inhibit corrosion, it requires a concentration ten times as high. In one experiment, a test specimen was kept in an aqueous solution of pertechnetate for 20 years and was still uncorroded. The mechanism by which pertechnetate prevents corrosion is not well-understood, but seems to involve the reversible formation of a thin surface layer. One theory holds that the pertechnetate reacts with the steel surface to form a layer of technetium dioxide which prevents further corrosion; the same effect explains how iron powder can be used to remove pertechnetate from water. An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element (Activated carbon can also be used for the same effect. Activated carbon, also called activated charcoal or activated coal, is a form of Carbon that has been processed to make it extremely porous and thus to ) The effect disappears rapidly if the concentration of pertechnetate falls below the minimum concentration or if too high a concentration of other ions is added.

As noted, the radioactive nature of technetium (3 MBq per liter at the concentrations required) makes this corrosion protection impractical in almost all situations. The becquerel (symbol Bq) is the SI derived unit of radioactivity. Nevertheless, corrosion protection by pertechnetate ions was proposed (but never adopted) for use in boiling water reactors. A boiling water reactor ( BWR) is a type of Nuclear reactor developed by the General Electric in the mid 1950s ^[10]

History

Search for element 43

For a number of years there was a gap in the periodic table between molybdenum (element 42) and ruthenium (element 44). Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 Many early researchers were eager to be the first to discover and name the missing element; its location in the table suggested that it should be easier to find than other undiscovered elements. It was first thought to have been found in platinum ores in 1828. Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 It was given the name polinium but it turned out to be impure iridium. Gottfried Wilhelm Osann ( 26 October 1796, Weimar – 10 August 1866, Würzburg) was a German chemist and physicist Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 Then in 1846 the element ilmenium was claimed to have been discovered but was determined to be impure niobium. Niobium (naɪˈoʊbiəm or columbium (/kəˈlʌmbiəm/ is a Chemical element that has the symbol Nb and Atomic number 41 This mistake was repeated in 1847 with the "discovery" of pelopium. ^[18] Dmitri Mendeleev predicted that this missing element, as part of other predictions, would be chemically similar to manganese and gave it the name ekamanganese. Dmitri Ivanovich Mendeleev (sometimes spelled Mendeleyev; Дми́трий Ива́нович Менделе́ев) ( &ndash) was a Russian chemist and Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn.

In 1877, the Russian chemist Serge Kern reported discovering the missing element in platinum ore. Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Kern named what he thought was the new element davyum, after the noted English chemist Sir Humphry Davy, but it was determined to be a mixture of iridium, rhodium and iron. Sir Humphry Davy 1st Baronet FRS MRIA (17 December 1778 &ndash 29 May 1829 was a British Chemist and inventor Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Another candidate, lucium, followed in 1896 but it was determined to be yttrium. Yttrium (ˈɪtriəm is a Chemical element with symbol Y and Atomic number 39 Then in 1908 the Japanese chemist Masataka Ogawa found evidence in the mineral thorianite which he thought indicated the presence of element 43. was a Japanese chemist known for the discovery of Nipponium. After graduating from the University of Tokyo, he studied under William Ramsay in London Thorianite is a rare mineral originally discovered by Ananda Coomaraswamy in 1904 as uraninite but recognized as a new species by W Ogawa named the element nipponium, after Japan (which is Nippon in Japanese). For a topic outline on this subject see List of basic Japan topics. In 2004 H. K Yoshihara utilized "a record of X-ray spectrum of Ogawa's nipponium sample from thorianite [which] was contained in a photographic plate preserved by his family. The spectrum was read and indicated the absence of the element 43 and the presence of the element 75 (rhenium). "^[19]

German chemists Walter Noddack, Otto Berg and Ida Tacke (later Mrs. Walter Noddack (* 17 August 1893 in Berlin, 7 December 1960 in Berlin) was a German chemist Ida Noddack ( 25 February 1896 - 1978 Née Ida Tacke, was a German Chemist and Physicist. Noddack) reported the discovery of element 75 and element 43 in 1925 and named element 43 masurium (after Masuria in eastern Prussia, now in Poland, the region where Walter Noddack's family originated). Prussia ( Latin: Borussia, Prutenia; Prūsija Prūsija Prusy Old Prussian: Prūsa) was most recently a historic state Poland (Polska officially the Republic of Poland ^[20] The group bombarded columbite with a beam of electrons and deduced element 43 was present by examining X-ray diffraction spectrograms. Ferrocolumbite, also called niobite, niobite-tantalite, columbate and columbite ] Mn)( Nb, Ta)2 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J X-radiation (composed of X-rays) is a form of Electromagnetic radiation. The spectrogram is the result of calculating the Frequency spectrum of Windowed frames of a compound signal. The wavelength of the X-rays produced is related to the atomic number by a formula derived by Henry Moseley in 1913. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Henry Gwyn Jeffreys Moseley ( November 23, 1887 – August 10, 1915) was an English physicist. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. Contemporary experimenters could not replicate the discovery, and in fact it was dismissed as an error for many years. ^[21][22]

In 1998 John T. Armstrong of the National Institute of Standards and Technology ran "computer simulations" of the 1925 experiments and obtained results quite close to those reported by the Noddack team. He claimed that this was further supported by work published by David Curtis of the Los Alamos National Laboratory measuring the (tiny) natural occurrence of technetium. Los Alamos National Laboratory (LANL (previously known at various times as Site Y, Los Alamos Laboratory, and Los Alamos Scientific Laboratory) is a ^[21][23] However, the Noddack's experimental results have never been reproduced, and they were unable to isolate any element 43. Debate still exists as to whether the 1925 team actually did discover element 43.

Official discovery and later history

Discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily conducted by Carlo Perrier and Emilio Segrè. For the University of Palermo in Buenos Aires, Argentina, see University of Palermo at B Emilio Gino Segrè ( February 1, 1905 – April 22, 1989) was an Italian Physicist and Nobel laureate in In the summer of 1936 Segrè and his wife visited the United States, first New York at Columbia University, where he had spent time the previous summer, and then Berkeley at Ernest O. Lawrence's Radiation Laboratory. Columbia University is a private University in the United States and a member of the Ivy League. Berkeley is a city on the east shore of San Francisco Bay in Northern California, in the United States. Ernest Orlando Lawrence ( August 8, 1901 – August 27, 1958) was an American physicist and Nobel Laureate best known for his The Ernest Orlando Lawrence Berkeley National Laboratory ( LBNL) is a U He persuaded cyclotron inventor Lawrence to let him take back some discarded cyclotron parts that had become radioactive. A cyclotron is a type of Particle accelerator. Cyclotrons accelerate Charged particles using a high- Frequency, alternating Voltage (potential In early 1937 Lawrence mailed him a molybdenum foil that had been part of the deflector in the cyclotron. Segrè enlisted his experienced chemist colleague Perrier to attempt to prove through comparative chemistry that the molybdenum activity was indeed Z = 43, an element not existent in nature because of its instability against nuclear decay. With considerable difficulty they finally succeeded in isolating three distinct decay periods (90, 80, and 50 days) that eventually turned out to be two isotopes, ⁹⁵Tc and ⁹⁷Tc, of technetium, the name given later by Perrier and Segrè to the first man-made element. ^[24] University of Palermo officials wanted them to name their discovery panormium, after the Latin name for Palermo, Panormus. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Palermo ( Sicilian: Palermu, Greek: Panormus, al-Madinah during Muslim rule is a historic City in The researchers instead named element 43 after the Greek word τεχνητός, meaning "artificial", since it was the first element to be artificially produced. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly ^[20][18] Segrè returned to Berkeley and immediately sought out Glenn T. Seaborg. Glenn Theodore Seaborg ( Glenn Teodor Sjöberg) ( April 19, 1912 &ndash February 25, 1999) won the 1951 Nobel Prize in Chemistry They isolated the technetium-99m isotope which is now used in some 10,000,000 medical diagnostic procedures annually. ^[25]

In 1952 astronomer Paul W. Merrill in California detected the spectral signature of technetium (in particular, light at 403. Paul Willard Merrill ( August 15 1887 &ndash July 19 1961) was an American Astronomer whose specialty was Spectroscopy. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ 1 nm, 423. 8 nm, 426. 8 nm, and 429. 7 nm) in light from S-type red giants. In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics A red giant is a luminous Giant star of low or intermediate mass (roughly 0 ^[10] These massive stars near the end of their lives were rich in this short-lived element, meaning nuclear reactions within the stars must be producing it. 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 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 This evidence was used to bolster the then unproven theory that stars are where nucleosynthesis of the heavier elements occurs. The word theory has many distinct meanings in different fields of Knowledge, depending on their methodologies and the context of discussion. Nucleosynthesis is the process of creating new atomic nuclei from preexisting Nucleons (protons and neutrons ^[26] More recently, such observations provided evidence that elements were being formed by neutron capture in the s-process. Neutron capture is a kind of Nuclear reaction in which an Atomic nucleus collides with one or more Neutrons and they merge to form a heavier nucleus The S-process or slow-neutron -capture-process is a Nucleosynthesis process that occurs at relatively low neutron density and intermediate temperature conditions in ^[10]

Since its discovery, there have been many searches in terrestrial materials for natural sources. In 1962, technetium-99 was isolated and identified in pitchblende from the Belgian Congo in extremely small quantities (about 0. The Belgian Congo ( Dutch: Belgisch Kongo French: Congo Belge German: Belgisch Kongo was the formal title of present-day Democratic Republic 2 ng/kg);^[10] there it originates as a spontaneous fission product of uranium-238. Spontaneous fission (SF is a form of Radioactive decay characteristic of very heavy Isotopes and is theoretically possible for any atomic nucleus whose mass is greater Uranium-238 (U-238 is the most common isotope of Uranium found in nature This discovery was made by B. T. Kenna and P. K. Kuroda. ^[27] There is also evidence that the Oklo natural nuclear fission reactor produced significant amounts of technetium-99, which has since decayed to ruthenium-99. Oklo is a region near the town of Franceville, in the Haut-Ogooué province of the Central African state of Gabon. A natural nuclear fission reactor is a Uranium deposit where analysis of Isotope Ratios has shown that self-sustaining Nuclear chain reactions ^[10]

Occurrence and production

Since technetium is unstable, only minute traces occur naturally in the Earth's crust as a spontaneous fission product of uranium. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Fission products are the atomic fragments left after a large nucleus fissions. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the In 1999 David Curtis (see above) estimated that a kilogram of uranium contains 1 nanogram (1×10⁻⁹ g) of technetium. ^[28] Extraterrestrial technetium was found in some red giant stars (S-, M-, and N-types) that contain an absorption line in their spectrum indicating the presence of this element. A red giant is a luminous Giant star of low or intermediate mass (roughly 0 ^[29]

Long-lived fission products
Property: t½ Unit: (Ma)		Yield (%)	Q * (KeV)	βγ *
99Tc	. Evolution of radioactivity in nuclear waste Nuclear fission produces Fission products, as well as Actinides from Nuclear fuel nuclei that capture Fission products are the atomic fragments left after a large nucleus fissions. Half-Life (computer-game page here It's already listed in the disambiguation page Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular See also Fission product Nuclear fission splits a heavy nucleus such as Uranium or Plutonium into two lighter nuclei which are called Fission The decay energy is the Energy released by a Nuclear decay. The energy difference of the Reactants is often written as Q: where Q Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Technetium-99 (99Tc is an isotope of Technetium which decays with a Half-life of 211000 years emitting soft beta rays but no gamma rays and has a 211	6. 1385	294	β
126Sn	. Tin-126 is a Radioisotope of Tin and one of only 7 long-lived Fission products While tin-126's Halflife of 230000 years translates to a 230	. 1084	4050	βγ
79Se	. Selenium-79 is a Radioisotope of Selenium present in Spent nuclear fuel and the wastes resulting from reprocessing this fuel 295	. 0447	151	β
93Zr	1. 93Zr is a Radioisotope of Zirconium with a Half life of 153 million years decaying with a low-energy Beta particle to Niobium 53	5. 4575	91	βγ
135Cs	2. Caesium-135 is a Caesium Radioisotope with a Half-life of 23 million years undergoing low-energy Beta decay to Barium -135 3	6. 9110	269	β
107Pd	6. Palladium -107 is the second longest lived ( Halflife of 65 million years and least radioactive ( Decay energy only 33 KeV, Specific activity 5	1. 2499	33	β
129I	15. Iodine-129 (129I is a Radioisotope of Iodine. Formation and decay 129I is primarily formed from the Fission 7	. 8410	194	βγ

Byproduct production of Tc-99 in fission wastes

In contrast with the rare natural occurrence, bulk quantities of technetium-99 are produced each year from spent nuclear fuel rods, which contain various fission products. Spent nuclear fuel, occasionally called used nuclear fuel, is Nuclear fuel that has been irradiated in a Nuclear reactor (usually at a Nuclear power Nuclear fuel is any material that can be consumed to derive Nuclear energy, by analogy to chemical Fuel that is burned to derive energy Fission products are the atomic fragments left after a large nucleus fissions. The fission of a gram of uranium-235 in nuclear reactors yields 27 mg of ⁹⁹Tc, giving technetium a fission product yield of 6. Uranium-235 is an isotope of uranium that differs from the element's other common isotope Uranium-238, by its ability to cause a rapidly expanding fission This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled See also Fission product Nuclear fission splits a heavy nucleus such as Uranium or Plutonium into two lighter nuclei which are called Fission 1%. ^[30] Other fissile isotopes also produce similar yields of technetium,^[10] e. In Nuclear engineering, a fissile material is one that is capable of sustaining a Chain reaction of Nuclear fission. g. 4. 9% from uranium-233 or 6. Uranium-233 is a Fissile artificial isotope of Uranium, which has been used in a few Nuclear reactors and has been proposed for much wider use as a 21% from plutonium-239. Plutonium-239 is an Isotope of Plutonium. Plutonium-239 is the primary Fissile isotope used for the production of Nuclear weapons although

It is estimated that up to 1994, about 49,000 TBq (78 metric tons) of technetium was produced in nuclear reactors, which is by far the dominant source of terrestrial technetium. The becquerel (symbol Bq) is the SI derived unit of radioactivity. This article is about the tonne or metric ton For other tons see Ton. ^[31] However, only a fraction of the production is used commercially. As of 2005, technetium-99 is available to holders of an ORNL permit for US$83/g plus packing charges. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Oak Ridge National Laboratory ( ORNL) is a multiprogram science and technology National laboratory managed for the United States Department of Energy by The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been ^[32]

Since the yield of technetium-99 as a product of the nuclear fission of both uranium-235 and plutonium-239 is moderate, it is present in radioactive waste of fission reactors and is produced when a fission bomb is detonated. Fission products are the atomic fragments left after a large nucleus fissions. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. The amount of artificially produced technetium in the environment exceeds its natural occurrence to a large extent. This is due to release by atmospheric nuclear testing along with the disposal and processing of high-level radioactive waste. Nuclear weapons tests are experiments carried out to determine the effectiveness yield and explosive capability of Nuclear weapons Throughout the twentieth century most nations Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose Due to its high fission yield and relatively high half-life, technetium-99 is one of the main components of nuclear waste. Its decay, measured in becquerels per amount of spent fuel, is dominant at about 10⁴ to 10⁶ years after the creation of the nuclear waste. ^[31]

An estimated 160 TBq (about 250 kg) of technetium-99 was released into the environment up to 1994 by atmospheric nuclear tests. The becquerel (symbol Bq) is the SI derived unit of radioactivity. ^[31] The amount of technetium-99 from nuclear reactors released into the environment up to 1986 is estimated to be on the order of 1000 TBq (about 1600 kg), primarily by nuclear fuel reprocessing; most of this was discharged into the sea. Nuclear reprocessing separates components of Spent nuclear fuel such as Reprocessed uranium Plutonium Minor In recent years, reprocessing methods have improved to reduce emissions, but as of 2005 the primary release of technetium-99 into the environment is by the Sellafield plant, which released an estimated 550 TBq (about 900 kg) from 1995–1999 into the Irish Sea. Sellafield is a nuclear processing and former electricity generating site close to the village of Seascale on the coast of the Irish Sea in Cumbria The Irish Sea ( Irish: Muir Éireann or Muir Meann; Scottish Gaelic: Muir Eireann Welsh: Môr Iwerddon, From 2000 onwards the amount has been limited by regulation to 90 TBq (about 140 kg) per year. ^[33]

As a result of nuclear fuel reprocessing, technetium has been discharged into the sea in a number of locations, and some seafood contains tiny but measurable quantities. For example, lobster from west Cumbria contains small amounts of technetium. The European lobster ( Homarus gammarus) (possibly referred as Crayfish) is a large European clawed Lobster. Boundaries and divisions Cumbria is neighboured by Northumberland, County Durham, North Yorkshire, Lancashire, and the Lieutenancy ^[34] The anaerobic, spore-forming bacteria in the Clostridium genus are able to reduce Tc(VII) to Tc(IV). An anaerobic organism is any Organism that does not require Oxygen for growth and may even die in its presence An endospore is a dormant, tough and non-reproductive structure produced by a small number of Bacteria from the Firmicute phylum The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Clostridium is a Genus of Gram-positive bacteria belonging to the Firmicutes. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic Clostridia bacteria play a role in reducing iron, manganese and uranium, thereby affecting these elements' solubility in soil and sediments. Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Their ability to reduce technetium may determine a large part of Tc's mobility in industrial wastes and other subsurface environments. ^[35]

The long half-life of technetium-99 and its ability to form an anionic species makes it (along with ¹²⁹I) a major concern when considering long-term disposal of high-level radioactive waste. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Iodine-129 (129I is a Radioisotope of Iodine. Formation and decay 129I is primarily formed from the Fission In addition, many of the processes designed to remove fission products from medium-active process streams in reprocessing plants are designed to remove cationic species like caesium (e. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Caesium or cesium (ˈsiːziəm is the Chemical element with the symbol Cs and Atomic number 55 g. , ¹³⁷Cs) and strontium (e. Caesium-137 (also spelled cesium is a radioactive Isotope of Caesium which is formed mainly by Nuclear fission. Strontium (ˈstrɒntiəm /ˈstrɒnʃiəm/) is a Chemical element with the symbol Sr and the Atomic number 38 g. , ⁹⁰Sr). Strontium-90 (90Sr is a Radioactive Isotope of Strontium, with a Half life of 28 Hence the pertechnetate is able to escape through these treatment processes. Current disposal options favor burial in geologically stable rock. The deep geological repository concept involves the placement of long-lived Radioactive waste, often Spent nuclear fuel, in rooms excavated deep within stable low-permeability The primary danger with such a course is that the waste is likely to come into contact with water, which could leach radioactive contamination into the environment. The anionic pertechnetate and iodide are less able to absorb onto the surfaces of minerals so they are likely to be more mobile. An iodide Ion is an iodine atom with a &minus1 charge. Compounds with iodine in formal Oxidation state &minus1 are called iodides

By comparison plutonium, uranium, and caesium are much more able to bind to soil particles. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Caesium or cesium (ˈsiːziəm is the Chemical element with the symbol Cs and Atomic number 55 For this reason, the environmental chemistry of technetium is an active area of research. An alternative disposal method, transmutation, has been demonstrated at CERN for technetium-99. Nuclear transmutation is the conversion of one Chemical element or Isotope into another which occurs through Nuclear reactions Natural transmutation occurs The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN This transmutation process is one in which the technetium (⁹⁹Tc as a metal target) is bombarded with neutrons to form the shortlived ¹⁰⁰Tc (half life = 16 seconds) which decays by beta decay to ruthenium (¹⁰⁰Ru). The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 If recovery of usable ruthenium is a goal, an extremely pure technetium target is needed; if small traces of the minor actinides such as americium and curium are present in the target, they are likely to undergo fission and form more fission products which increase the radioactivity of the irradiated target. The minor actinides are the Actinide elements in used Nuclear fuel other than Uranium and Plutonium, which are termed the Major actinides Americium (ˌæməˈrɪsiəm is a Synthetic element that has the symbol Am and Atomic number 95 This article is about the chemical element Curium for the ancient city also called Curium (located in Cyprus see Kourion Curium (ˈkjuːriəm Fission products are the atomic fragments left after a large nucleus fissions. The formation of ¹⁰⁶Ru (half life 374 days) from the fresh fission is likely to increase the activity of the final ruthenium metal, which will then require a longer cooling time after irradiation before the ruthenium can be used. Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44

The actual production of technetium-99 from spent nuclear fuel is a long process. During fuel reprocessing, it appears in the waste liquid, which is highly radioactive. After sitting for several years, the radioactivity has fallen to a point where extraction of the long-lived isotopes, including technetium-99, becomes feasible. Several chemical extraction processes are used yielding technetium-99 metal of high purity. ^[10]

Neutron activation of molybdenum or other pure elements

The meta stable (a state where the nucleus is in an excited state) isotope ^99mTc is produced as a fission product from the fission of uranium or plutonium in nuclear reactors. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies Fission products are the atomic fragments left after a large nucleus fissions. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled Because used fuel is allowed to stand for several years before reprocessing, all ⁹⁹Mo and ^99mTc will have decayed by the time that the fission products are separated from the major actinides in conventional nuclear reprocessing. Major actinides is a term used in the Nuclear power industry that refers to the Plutonium and Uranium present in used Nuclear fuel, as opposed The PUREX raffinate will contain a high concentration of technetium as TcO₄^- but almost all of this will be ⁹⁹Tc. In Solvent extraction, a raffinate is a Liquid stream that remains after the extraction with the immiscible liquid to remove solutes from the The vast majority of the ^99mTc used in medical work is formed from ⁹⁹Mo which is formed by the neutron activation of ⁹⁸Mo. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. ⁹⁹Mo has a half-life of 67 hours, so short-lived ^99mTc (half-life: 6 hours), which results from its decay, is being constantly produced. ^[36] The hospital then chemically extracts the technetium from the solution by using a technetium-99m generator ("technetium cow", also occasionally called a "molybdenum cow"). A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of Technetium

The normal technetium cow is an alumina column which contains molybdenum-98; in as much as aluminium has a small neutron cross section, it is convenient for an alumina column bearing inactive ⁹⁸Mo to be irradiated with neutrons to make the radioactive Mo-99 column for the technetium cow. ^[37] By working in this way, there is no need for the complex chemical steps which would be required to separate molybdenum from a fission product mixture. This alternative method requires that an enriched uranium target be irradiated with neutrons to form ⁹⁹Mo as a fission product, then separated. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Fission products are the atomic fragments left after a large nucleus fissions. ^[38]

Other technetium isotopes are not produced in significant quantities by fission; when needed, they are manufactured by neutron irradiation of parent isotopes (for example, ⁹⁷Tc can be made by neutron irradiation of ⁹⁶Ru).

Isotopes

Main article: isotopes of technetium

Technetium is one of the two elements in the first 82 that have no stable isotopes (in fact, it is the lowest-numbered element that is exclusively radioactive); the other such element is promethium. Technetium ( Tc) is one of the two elements in the first 82 that have no stable Isotopes (in fact it is the lowest-numbered element that is exclusively radioactive Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Promethium (prəˈmiːθiəm/ /proʊˈmiːθiəm is a Chemical element with the symbol Pm and Atomic number 61 ^[39] The most stable radioisotopes are ⁹⁸Tc (half-life of 4. 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 Half-Life (computer-game page here It's already listed in the disambiguation page 2 Ma), ⁹⁷Tc (half-life: 2. Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular 6 Ma) and ⁹⁹Tc (half-life: 211. 1 ka). Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular ^[40]

Twenty-two other radioisotopes have been characterized with atomic masses ranging from 87. The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass 933 u (⁸⁸Tc) to 112. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express 931 u (¹¹³Tc). Most of these have half-lives that are less than an hour; the exceptions are ⁹³Tc (half-life: 2. 75 hours), ⁹⁴Tc (half-life: 4. 883 hours), ⁹⁵Tc (half-life: 20 hours), and ⁹⁶Tc (half-life: 4. 28 days). ^[40]

Technetium also has numerous meta states. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies ^97mTc is the most stable, with a half-life of 90. 1 days (0. 097 MeV). This is followed by ^95mTc (half life: 61 days, 0. 038 MeV), and ^99mTc (half-life: 6. 01 hours, 0. 143 MeV). ^99mTc only emits gamma rays, subsequently decaying to ⁹⁹Tc. Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions ^[40]

For isotopes lighter than the most stable isotope, ⁹⁸Tc, the primary decay mode is electron capture, giving molybdenum. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Electron capture (sometimes called inverse beta decay) is a Decay mode for Isotopes that will occur when there are too many Protons in the Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo For the heavier isotopes, the primary mode is beta emission, giving ruthenium, with the exception that ¹⁰⁰Tc can decay both by beta emission and electron capture. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Ruthenium (ruːˈθiːniəm is a Chemical element that has the symbol Ru and Atomic number 44 ^[40][41]

Technetium-99 is the most common and most readily available isotope, as it is a major product of the fission of uranium-235. One gram of ⁹⁹Tc produces 6. 2×10⁸ disintegrations a second (that is, 0. 62 GBq/g). The becquerel (symbol Bq) is the SI derived unit of radioactivity. ^[42]

Stability of technetium isotopes

Technetium and promethium are unusual light elements in that they have no stable isotopes. Promethium (prəˈmiːθiəm/ /proʊˈmiːθiəm is a Chemical element with the symbol Pm and Atomic number 61 The reason for this is somewhat complicated. ^[43]

Using the liquid drop model for atomic nuclei, one can derive a semiempirical formula for the binding energy of a nucleus. In Nuclear physics, the semi-empirical mass formula ( SEMF) sometimes also called Weizsäcker's formula is a formula used to approximate the Mass This formula predicts a "valley of beta stability" along which nuclides do not undergo beta decay. A nuclide (from lat nucleus is a species of Atom characterized by the constitution of its nucleus and hence by the number of Protons, the number of Nuclides that lie "up the walls" of the valley tend to decay by beta decay towards the center (by emitting an electron, emitting a positron, or capturing an electron). The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron.

For a fixed odd number of nucleons A, the graph of binding energies vs. atomic number (number of protons) is shaped like a parabola (U-shaped), with the most stable nuclide at the bottom. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular A single beta decay or electron captures then transforms one nuclide of mass A into the next or preceding one, if the product has a lower binding energy and the difference in energy is sufficient to drive the decay mode. When there is only one parabola, there can be only one stable isotope lying on that parabola.

For a fixed even number of nucleons A, the graph is jagged and is better visualized as two separate parabolas for even and odd atomic numbers, because isotopes with an even number of protons and an even number of neutrons are more stable than isotopes with an odd number of neutrons and an odd number of protons. In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular

When there are two parabolas, that is, when the number of nucleons is even, it can happen (rarely) that there is a stable nucleus with an odd number of neutrons and an odd number of protons (although there are only 4 truly stable examples as opposed to very long-lived: the light nuclei: ²H, ⁶Li, ¹⁰B, ¹⁴N). In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. However, if this happens, there can be no stable isotope with an even number of neutrons and an even number of protons.

For technetium (Z=43), the valley of beta stability is centered at around 98 nucleons. However, for every number of nucleons from 95 to 102, there is already at least one stable nuclide of either molybdenum (Z=42) or ruthenium (Z=44). For the isotopes with odd numbers of nucleons, this immediately rules out a stable isotope of technetium, since there can be only one stable nuclide with a fixed odd number of nucleons. For the isotopes with an even number of nucleons, since technetium has an odd number of protons, any isotope must also have an odd number of neutrons. In such a case, the presence of a stable nuclide having the same number of nucleons and an even number of protons rules out the possibility of a stable nucleus. ^[44]

References

Works cited

Notes

External links

• WebElements.com – Technetium
• pubs.acs.org – ACS article on validity of Noddack and Tacke's discovery

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