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Let’s Learn About TECHNETIUM!

Technetium is a chemical element with the symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive, none of which is stable other than the fully ionized state of 97Tc. Nearly all available technetium is produced as a synthetic element. Naturally happening technetium is an unplanned quick fission product in uranium ore and thorium ore, the most common source, or the product of neutron take and hold to prevent release in molybdenum ores. The silvery gray, transparent change metamorphising metal lies between manganese and rhenium in group 7 of the list of all elements, and its chemical properties are halfway between those of both beside elements. The most common naturally happening isotope is 99Tc, in traces only.

Many of technetium’s properties had been (described a possible future event) by Dmitri Mendeleev before it was discovered. Mendeleev noted a gap in his list of all elements and gave the undiscovered element the temporary name ekamanganese (Em). In 1937, technetium (specifically the technetium-97 isotope) became the first mostly (not made by nature/fake) element to be produced, because of this its name (from the Greek τεχνητός, meaning “Craft, Art or (not made by nature/fake)”, + -ium).

One short-lived (ray of invisible energy)-sending out nuclear isomer, technetium-99m, is used in nuclear medicine for a wide variety of tests, such as bone cancer (identifications of diseases or problems, or their causes). The ground state of the nuclide technetium-99 is used as a gamma-ray-free source of beta particles. Long-lived technetium isotopes produced commercially are (things produced along with something else) of the fission of uranium-235 in nuclear reactors and are (pulled out or taken from something else) from nuclear fuel rods. Because no isotope of technetium has a half-life longer than 4.21 million years (technetium-97), the 1952 detection of technetium in red giants helped to prove that stars can produce heavier elements.

From the 1860s through 1871, early forms of the list of all elements proposed by Dmitri Mendeleev contained a gap between molybdenum (element 42) and ruthenium (element 44). In 1871, Mendeleev (described a possible future event) this missing element would occupy the empty place below manganese and have almost the same chemical properties. Mendeleev gave it the temporary name ekamanganese (from eka-, the Withoutkrit word for one) because the (described a possible future event) element was one place down from the known element manganese.

The discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segre.[14] In mid-1936, Segre visited the United States, first Columbia University in New York and then the Lawrence Berkeley National Laboratory in California. He convinced cyclotron inventor Ernest Lawrence to let him take back some thrown-out cyclotron parts that had become radioactive. Lawrence mailed him a molybdenum foil that had been part of the (object that pushes aside the flow of something) in the cyclotron.

Segre (joined the military) his fellow worker Perrier to attempt to prove, through (serving to compare two or more things) chemistry, that the molybdenum activity was in fact from an element with the atomic number 43. In 1937, th
ey succeeded in (separating far from others) the isotopes technetium-95m and technetium-97. University of Palermo (people in charge of something) wanted them to name their discovery “panormium”, after the Latin name for Palermo, Panormus. In 1947 element 43 was named after the Greek word τεχνητός, meaning “(not made by nature/fake)”, since it was the first element to be (not in a natural way/in a fake way) produced. Segre returned to Berkeley and met Glenn T. Seaborg. They (separated far from others) the metastable isotope technetium-99m, which is now used in some ten million medical disease-identifying procedures every year.

In 1952, the star expert-related Paul W. Merrill in California detected the (related to ghosts or the colors of the rainbow) signature of technetium (specifically wavelengths of 403.1 nm, 423.8 nm, 426.2 nm, and 429.7 nm) in light from S-type red giants. The stars were near the end of their lives but were rich in the short-lived element, which pointed to/showed that it was being produced in the stars by nuclear reactions. That (event(s) or object(s) that prove something) helped (or increased) the educated guess that heavier elements are the product of (the act of creating atoms) in stars. More (not very long ago), such (instances of watching, noticing, or making statements) gave/given (event(s) or object(s) that prove something) that elements are formed by neutron take and hold (to prevent release) in the s-process.

Since that discovery, there have been many searches in (on land) materials for natural sources of technetium. In 1962, technetium-99 was (far apart from others) and identified in pitchblende from the Belgian Congo in very small amounts (about 0.2 ng/kg), where it starts as an unplanned (and sudden) fission product of uranium-238. The Oklo natural nuclear fission reactor contains (event(s) or object(s) that prove something) that big amounts of technetium-99 were produced and have since (rotted/became ruined or worse) into ruthenium-99.

Technetium is a silvery-gray radioactive metal with an appearance almost the same as platinum, commonly received/got as a gray powder. The crystal structure of the bulk (completely/complete, with nothing else mixed in) metal is six-sided close-packed. The crystal structure of the nanodisperse (completely/complete, with nothing else mixed in) metal is cubic. Nanodisperse technetium does not have a split NMR spectrum, while six-sided bulk technetium has the Tc-99-NMR spectrum split in 9 satellites. Atomic technetium has (typical and expected) emission lines at wavelengths of 363.3 nm, 403.1 nm, 426.2 nm, 429.7 nm, and 485.3 nm.

The metal form is (a) little paramagnetic, meaning its magnetic dipoles match up/make even with external magnetic fields, but will assume random (directions of pointing) once the field is removed. Pure, metallic, single-crystal technetium becomes a type-II superconductor at temperatures below 7.46 K. Below this temperature, technetium has a very high magnetic penetration depth, greater than any other element except niobium.

Technetium happens naturally in the Earth’s crust in minute concentrations of about 0.003 parts per trillion. Technetium is so rare because the half-lives of 97Tc and 98Tc are only 4.2 million years. More than a thousand of such periods have passed since the (creation and construction/ group of objects) of the Earth, so the chance for the survival of even one atom of very old (from the beginning of time) technetium is effectively zero. However, small amounts exist as unplanned (and sudden) fission products in uranium ores. A kilogram of uranium contains a guessed (number) 1 nanogram (10aˆ’9 g) equal to ten trillion atoms of technetium. Some red giant stars with the (related to ghosts or the colors of the rainbow) types S-, M-, and N contain a (related to ghosts or the colors of the rainbow) (mental concentration/picking up of a liquid) line pointing to/showing the presence of technetium. These red-giants are known informally as technetium stars.

Technetium-99m (“m” points to/shows that this is a metastable nuclear isomer) is used in radioactive isotope medical tests. For example, Technetium-99m is a radioactive tracer that (X-rays, MRIs, etc.) equipment tracks in the human body. It is well suited to the role because it gives off easily detectable 140 keV (rays of invisible energy), and its half-life is 6.01 hours (meaning that about 94% of it (rots/becomes ruined/gets worse) to technetium-99 in 24 hours). The chemistry of technetium allows it to be bound to a variety of (related to the chemicals in living things) compounds, each of which decides/figures out how it is (chemically processed and used up) and deposited in the body, and this single isotope can be used for a large number of medical tests (to get information). More than 50 common radiopharmaceuticals are based on technetium-99m for imaging and functional studies of the brain, heart muscle, thyroid, lungs, liver, gall bladder, (organs that create urine), skeleton, blood, and tumors.

The longer-lived isotope, technetium-95m with a half-life of 61 days, is used as a radioactive tracer to study the movement of technetium in (the health of the Earth/the surrounding conditions) and in plant and animal systems.

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Let’s Learn About THORIUM!

Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and discolors and ruins black when it is exposed to air, forming thorium dioxide; it is moderately soft, bendable, and has a high melting point. Thorium is an electropositive actinide whose chemistry is ruled-over by the +4 oxidation state; it is quite a catalyst and can catch fire in air when finely divided.

All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it (rots/becomes ruined/gets worse) very slowly via alpha (rotted, inferior, or ruined state), starting a decay chain named the thorium series that ends at stable 208Pb. On Earth, thorium and uranium are the only significantly radioactive elements that still happen naturally in large amounts as very old (from the beginning of time) elements. Thorium is guessed (number) to be over three times as plentiful as uranium in the Earth’s crust, and is mostly high-quality from monazite sands as a (something produced along with something else) of (pulling out or taking from something else) rare-earth metals.

Thorium was discovered in 1828 by the Norwegian inexperienced/low quality mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder. Its first applications were developed in the late 19th century. Thorium’s radioactivity was widely admitted/recognized/responded to during the first at least 20 years of the 20th century. In the second half of the century, thorium was replaced in many uses due to concerns about its radioactivity.

The (firm and steady nature/lasting nature/strength) of the Roman currency relied to a high degree on the supply of silver bars, mostly from Spain, which Roman miners produced on a scale (unlike any other thing in the world) before the discovery of the New World. Reaching a peak production of 200 tonnes per year, a guessed (number) silver stock of 10000 tonnes circulated in the Roman (process of people making, selling, and buying things) in the middle of the second century AD, five to ten times larger than the combined amount of silver available to (very old time in history) Europe and the Abbasid Important Muslim religious leaderate around AD 800.

Thorium was discovered in 1828 by the Norwegian inexperienced/low quality mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder. Its first applications were developed in the late 19th century. Thorium’s radioactivity was widely admitted/recognized/responded to during the first at least 20 years of the 20th century. In the second half of the century, thorium was replaced in many uses due to concerns about its radioactivity.

Thorium is still being used as a mixture element in TIG welding electrodes but is slowly being replaced in the field with different compositions. It was also material in high-end optics and scientific instrumentation, used in some broadcast vacuum tubes, and as the light source in gas mantles, but these uses have become not important. Some say as a replacement for uranium as nuclear fuel in nuclear reactors, and (more than two, but not a lot of) thorium reactors have been built. Thorium is also used in strengthening magnesium, coating tungsten wire in electrical equipment, controlling the grain size of tungsten in electric lamps, high-temperature red-hot containers, and glasses including camera and scientific (sensitive measuring/recording device) lenses. Other uses for thorium include heat-resistant ceramics, aircraft engines, and in light bulbs.

In 1828, Morten Thrane Esmark found a black mineral on Løvøya island, Telemark county, Norway. He was a Norwegian priest and inexperienced/low quality mineralogist who studied the minerals in Telemark, where he served as vicar. He commonly sent the most interesting medical samples/examples, such as this one, to his father, Jens Esmark, a noted mineralogist and professor of mineralogy and (the study of rocks) at the Royal Frederick University in Christiania (today called Oslo). The older (person) Esmark decided/figured out that it was not a known mineral and sent a sample to Berzelius for examination. Berzelius decided/figured out that it contained a new element. He published his findings in 1829, having (separated far from others) an impure sample by reducing KThF5 with potassium metal. Berzelius reused the name of the previous supposed element discovery and named the source mineral thorite.

Jöns Jacob Berzelius, who first identified thorium as a new element.  Berzelius made some initial descriptions of the new metal and its chemical compounds: he correctly decided/figured out that the thorium-oxygen mass ratio of thorium oxide was 7.5 (its actual value is close to that, ~7.3), but he assumed the new element was divalent rather than tetravalent, and so calculated that the atomic mass was 7.5 times that of oxygen (120 amu); it is actually 15 times as large. He decided/figured out that thorium was a very electropositive metal, ahead of cerium and behind zirconium in electropositivity. Metallic thorium was (far apart from others) for the first time in 1914 by Dutch small business starters Dirk Lely Jr. and Source of gold, silver, or something valuablewijk Hamburger.

In the list of all elements published by Dmitri Mendeleev in 1869, thorium and the rare-earth elements were placed outside the main body of the table, at the end of each up-and-down period after the alkaline earth metals. This reflected the belief at that time that thorium and the rare-earth metals were divalent. With the later recognition that the rare earths were mostly trivalent and thorium was tetravalent, Mendeleev moved cerium and thorium to group IV in 1871, which also contained the modern carbon group (group 14) and titanium group (group 4), because their maximum oxidation state was +4. Cerium was soon removed from the main body of the table and placed in a separate lanthanide series; thorium was left with group 4 as it had almost the same properties to its supposed lighter congeners in that group, such as titanium and zirconium.

While thorium was discovered in 1828 its first application dates only from 1885, when Austrian chemist Carl Auer von Welsbach invented the gas mantle, a portable source of light which produces light from the glow of thorium oxide when heated by burning gaseous fuels. Many uses were (after that) found for thorium and its compounds, including ceramics, carbon arc lamps, heat-resistant red-hot containers, and as helping forces for industrial chemical reactions such as the oxidation of strong-smelling chemical to nitric acid.

Up to the late 19th century, chemists (every single person agreed) that thorium and uranium were the same as hafnium and tungsten; the existence of the lanthanides in the sixth row was carefully thought about/believed to be a one-off lucky accident. In 1892, British chemist Henry Bassett said a second extra-long list of all elements row to change something (to help someone)/take care of someone known and undiscovered elements, (thinking about/when one thinks about) thorium and uranium to be the same as the lanthanides. In 1913, Danish physicist Niels Bohr published a (related to ideas about how things work or why they happen) model of the atom and its electron orbitals, which soon gathered wide acceptance. The model pointed to/showed that the seventh row of the list of all elements should also have f-shells filling before the d-shells that were filled in the change (from one thing to another) elements, like the sixth row with the lanthanides coming before the 5d change (from one thing to another) metals. The existence of a second inner change (from one thing to another) series, in the form of the actinides, was not accepted until (things that are almost the same as other things) with the electron structures of the lanthanides had been established; Bohr suggested that the filling of the 5f orbitals may be delayed to after uranium.

It was only with the discovery of the first transuranic elements, which from plutonium onward have most in control/most common +3 and +4 oxidation states like the lanthanides, that it was (understood/made real/achieved) that the actinides were in fact filling f-orbitals rather than d-orbitals, with the change (from one thing to another)-metal-like chemistry of the early actinides being the exception and not the rule. In 1945, when American physicist Glenn T. Seaborg and his team had discovered the transuranic elements (element) and curium, he proposed the actinide idea, (understanding/making real/achieving) that thorium was the second member of an f-block actinide series the same as the lanthanides, instead of being the heavier congener of hafnium in a fourth d-block row.

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Let’s Learn About HAFNIUM!

Hafnium is a chemical element with the symbol Hf and atomic number 72. A shiny, silvery gray, tetravalent change metamorphosis metal, hafnium chemically looks like zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Coster and Hevesy, making it the second-last stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered.

Hafnium is used in thin threads and electrodes. Some (element used to make electronic circuits) lie/construction processes use its oxide for electronic devicess at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.

Hafnium’s large neutron take and hold (to prevent release) cross section makes it a good material for neutron (mental concentration/picking up of a liquid) in control rods in nuclear power plants, but at the same time needs/demands that it be removed from the neutron-clear/open and honest (slow chemical breakdown of something/rust, etc.)-resistant zirconium mixtures (of metals) used in nuclear reactors.

Hafnium is a shiny, silvery, (able to be flattened or drawn into wire) metal that is (slow chemical breakdown of something/rust, etc.)-resistant and chemically almost the same as zirconium[6] (due to its having the same number of valence electrons, being in the same group, but also to relativistic effects; the expected (act of something getting bigger, wider, etc.) of atomic radii from period 5 to 6 is almost exactly cancelled out by the lanthanide contraction). Hafnium changes from its alpha form, a six-sided close-packed (something made of crossed strips of wood, metal, etc.), to its beta form, a body-centered cubic (something made of crossed strips of wood, metal, etc.), at 2388 K.[7] The physical properties of hafnium metal samples are very (much) affected by zirconium (dirt, dust, etc.), especially the nuclear properties, as these two elements are among the hardest to separate because of their chemical (thing that’s almost the same as another thing).

A important/famous physical difference between these metals is their density, with zirconium having about one-half the density of hafnium. The most famous nuclear properties of hafnium are its high thermal neutron take and hold (to prevent release) cross section and that the centers (of cells or atoms) of (more than two, but not a lot of) different hafnium isotopes easily soak up (like a towel) two or more neutrons each. In contrast with this, zirconium is practically clear/open and honest to thermal neutrons, and it is commonly used for the metal parts/pieces of nuclear reactors – especially the covering of their nuclear fuel rods.

Hafnium reacts in air to form a (serving or acting to prevent harm) film that stops further (slow chemical breakdown of something/rust, etc.). The metal is not easily attacked by acids but can be oxidized with halogens or it can be burnt in air. Like its sister metal zirconium, finely divided hafnium can (start a fire/catch on fire) in a sudden and unplanned way in air. The metal is resistant to (mainly studied) alkalis.

The chemistry of hafnium and zirconium is so almost the same that the two cannot be separated on the basis of different/disagreeing chemical reactions. The melting points and boiling points of the compounds and the (ability to be dissolved in something) in solvents are the major differences in the chemistry of these twin elements.

The heavy mineral sands ore deposits of the titanium ores ilmenite and rutile yield most of the mined zirconium, and therefore also most of the hafnium.

Zirconium is a good nuclear fuel-rod covering metal, with the desirable properties of a very low neutron capture (thin slice that can be looked at) and good chemical (firm and steady nature/lasting nature/strength) at high temperatures. However, because of hafnium’s neutron-soaking up (like a towel) properties, in zirconium would cause it to be far less useful for nuclear-reactor uses. So, a nearly complete separation of zirconium and hafnium is necessary for their use in nuclear power. The production of hafnium-free zirconium is the main source for hafnium.

The chemical properties of hafnium and zirconium are nearly identical, which makes the two very hard to separate. The methods first used — fractional crystallization of ammonium fluoride salts or the fractional summary/(when something is boiled down) of the chloride — have not proven good for an industrial-scale production. After zirconium was chosen as material for nuclear reactor programs in the 1940s, a separation method had to be developed. Liquid-liquid extraction processes with a wide variety of solvents were developed and are still used for the production of hafnium. About half of all hafnium metal manufactured is produced as a (something produced along with something else) of zirconium (good taste/good manners/improvement). The end product of the separation is hafnium(IV) chloride. The cleaned hafnium(IV) chloride is converted to the metal by reduction with magnesium or sodium, as in the Kroll process.

HfCl4 + 2 Mg (1100 °C) a†’ 2 MgCl2 + Hf
Further cleaning is produced/made happen by a chemical transport reaction developed by Arkel and de Boer: In a closed vessel, hafnium reacts with iodine at temperatures of 500 °C, forming hafnium(IV) iodide; at a tungsten thin thread of 1700 °C the reverse reaction happens, and the iodine and hafnium are set free. The chemical  forms a solid coating at the tungsten thin thread, and the iodine can react with added/more hafnium, resulting in a steady iodine turnover.

Hf + 2 I2 (500 °C) a†’ HfI4
HfI4 (1700 °C) a†’ Hf + 2 I2

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