Scandium:a chemical element with symbol Sc

Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallictransition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and thelanthanoids. It was discovered in 1879 by spectral analysis, of the minerals euxenite and gadolinite from Scandinavia.HP Pavilion DV4 Battery

Scandium is present in most of the deposits of rare earth and uranium compounds, but it is extracted from these ores in only a few mines worldwide. Because of the low availability and the difficulties in the preparation of metallic scandium, which was first done in 1937, it took until the 1970s before applications for scandium were developed.HP Pavilion DV4-1000 Battery

The positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains its only major application.

The properties of scandium compounds are intermediate between those of aluminium and yttrium. HP Pavilion DV4-1000EA Battery

A diagonal relationship exists between the behavior of magnesium and scandium, just as there is between beryllium and aluminium. In the chemical compounds of the elements shown as group 3, above, the predominant oxidation state is +3.HP Pavilion DV4-1000ET Battery

Chemical characteristics of the element

Scandium metal is soft metal with a silvery appearance. It develops a slightly yellowish or pinkish cast when oxidized by air. It is susceptible to weathering and dissolves slowly in most dilute acids. It does not react with a 1:1 mixture ofnitric acid (HNO3) and hydrofluoric acid (HF), possibly due to the formation of an impermeable passive layer.HP Pavilion DV4-1001 Battery

Scandium exists naturally exclusively as the isotope 45Sc, which has a nuclear spin of 7/2. Thirteen radioisotopes have been characterized with the most stable being 46Sc with a half-life of 83.8 days, 47Sc with a half-life of 3.35 days, and 48Sc with a half-life of 43.7 hours. HP Pavilion DV4-1001AX Battery

All of the remaining radioactive isotopes have half-lives that are less than 4 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has five meta states with the most stable being 44mSc (t½ = 58.6 h).[3]

The isotopes of scandium range from 36Sc to 60Sc. HP Pavilion DV4-1001TU Battery

The primary decay mode at masses lower than the only stable isotope, 45Sc, is electron capture, and the primary mode at masses above it is beta emission. The primary decay products at atomic weights below 45Sc are calcium isotopes and the primary products from higher atomic weights are titanium isotopes.HP Pavilion DV4-1001TX Battery

Occurrence

In terms of earth's crust, scandium is not particularly rare, Estimates vary from 18 to 25 ppm, which is comparable to the abundance of cobalt (20–30 ppm). Scandium is only the 50th most common element on earth (35th most abundant in the crust, but it is the 23rd most common element in the sun).HP Pavilion DV4-1002 Battery

However, scandium is distributed sparsely and occurs in trace amounts in many minerals.[5] Rare minerals from Scandinavia[6]and Madagascar[7] such as thortveitite, euxenite, and gadolinite are the only known concentrated sources of this element. Thortveitite can contain up to 45% of scandium in the form ofscandium(III) oxide.HP Pavilion DV4-1002AX Battery

The stable form of scandium is created in supernovas via the r-process.

Production

World production of scandium is in the order of 2 tonnes per year in the form of scandium oxide. The primary production is 400 kg while the rest is from stockpiles of Russia generated during the Cold War. HP Pavilion DV4-1002TU Battery

In 2003, only three mines produced scandium: the uranium and iron mines in Zhovti Vody in Ukraine, the rare earth mines in Bayan Obo, China and the apatite mines in the Kola peninsula, Russia. In each case, scandium is a byproduct from the extraction of other elements[9] and is sold as scandium oxide.HP Pavilion DV4-1002TX Battery

The production of metallic scandium is in the order of 10 kg per year.[9][10] The oxide is converted to scandium fluoride andreduced with metallic calcium.

Madagascar and Iveland-Evje region in Norway have the only deposits of minerals with high scandium content, thortveitite(Sc,Y)2(Si2O7) and kolbeckite ScPO4·2H2O, but these are not being exploited.HP Pavilion DV4-1003AX Battery

The absence of reliable, secure, stable and long term production has limited commercial applications of scandium. Despite this low level of use, scandium offers significant benefits. Particularly promising is the strengthening of aluminium alloys with as little as 0.5% scandium. HP Pavilion DV4-1003TU Battery

Scandium-stabilized zirconia enjoys a growing market demand for use as a high efficiency electrolyte in solid oxide fuel cells.

Compounds

The chemistry is almost completely dominated by the trivalent ion, Sc3+. The radii of M3+ ions in the table below indicate that in terms of chemical properties, scandium ions are more similar to those of yttrium than to those of aluminium. In part for this similarity, scandium is often classified as a lanthanide-like element.HP Pavilion DV4-1003TX Battery

Oxides and hydroxides

The oxide Sc2O3 and the hydroxide Sc(OH)3 are amphoteric:[11]

Sc(OH)3 + 3 OH? ? Sc(OH)3?
6

Sc(OH)3 + 3 H+ + 3 H2O ? [Sc(H2O)6]3+

The ?- and ?- forms of scandium oxide hydroxide (ScO(OH)), are isostructural with their aluminium oxide hydroxidecounterparts.[12] Solutions of Sc3+ in water are acidic because of hydrolysis.HP Pavilion DV4-1004AX Battery

Halides and pseudohalides

The halides ScX3 (X = Cl, Br, I) are very soluble in water, but ScF3 is insoluble. In all four halides the scandium is 6-coordinated. The halides are Lewis acids; for example, ScF3 dissolves a solution containing excess fluoride to form [ScF6]3?. The coordination number 6 is typical of Sc(III). HP Pavilion DV4-1004TU Battery

In the larger Y3+ and La3+ ions, coordination numbers of 8 and 9 are common.Scandium(III) triflate is sometimes used as a Lewis acid catalyst in organic chemistry.

Organic derivatives

Scandium forms a series of organometallic compounds with cyclopentadienyl ligands (Cp), similar to the behavior of the lanthanide.HP Pavilion DV4-1004TX Battery

One example is the chlorine-bridged dimer, [ScCp2Cl]2 and related derivatives of pentamethylcyclopentadienylligands.[13]

Uncommon oxidation states

Compounds that feature scandium in the oxidation state other than +3 are rare but well characterized. The blue-black compound CsScCl3 is one of the simplest. HP Pavilion DV4-1005TX Battery

This material adopts a sheet-like structure that exhibits extensive bonding between the scandium(II) centers.[14] Scandium hydride is not well understood, although it appears not to be a saline hydride of Sc(II). As is observed for most elements, a diatomic scandium hydride has been observed spectroscopically at high temperatures in the gas phase.HP Pavilion DV4-1006TX Battery

Scandium borides and carbides are non-stoichiometric, as is typical for neighboring elements.

Dmitri Mendeleev, creator of the periodic table, predicted the existence of an element ekaboron, with an atomic mass between 40 and 48 in 1869. HP Pavilion DV4-1007TX Battery

Lars Fredrik Nilsonand his team detected this element in the minerals euxenite and gadolinite. Nilson prepared 2 grams of scandium oxide of high purity.[16][17] He named the element scandium, from the Latin Scandia meaning "Scandinavia". Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized the correspondence and notified Mendeleev.HP Pavilion DV4-1008TX Battery

Metallic scandium was produced for the first time in 1937 by electrolysis of a eutectic mixture, at 700–800 °C, of potassium, lithium, and scandium chlorides.[19]The first pound of 99% pure scandium metal was produced in 1960. The use for aluminium alloys began in 1971, following a US patent.[20] Aluminium-scandium alloys were also developed in the USSR.HP Pavilion DV4-1009TX Battery

The addition of scandium to aluminium limits the excessive grain growth that occurs in the heat-affected zone of welded aluminium components. This has two beneficial effects: the precipitated Al3Sc forms smaller crystals than are formed in other aluminium alloysand the volume of precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys is reduced.HP Pavilion DV4-1010TX Battery

Both of these effects increase the usefulness of the alloy. However, titanium alloys, which are similar in lightness and strength, are cheaper and much more widely used.[23]

The main application of scandium by weight is in aluminium-scandium alloys for minor aerospace industry components. These alloys contain between 0.1% and 0.5% of scandium. HP Pavilion DV4-1011TX Battery

They were used in the Russian military aircraft, specifically the MiG-21 and MiG-29.

Some items of sports equipment, which rely on high performance materials, have been made with scandium-aluminium alloys, includingbaseball bats,[24] and bicycle[25] frames and components. Lacrosse sticks are also made with scandium-titanium alloys to take advantage of the strength of titanium. HP Pavilion DV4-1012TX Battery

The American firearm manufacturing company Smith & Wesson produces revolvers with frames composed of scandium alloy and cylinders of titanium or carbon steel.

Approximately 20 kg (as Sc2O3) of scandium is used annually in the United States to make high-intensity discharge lamps.HP Pavilion DV4-1013TX Battery

Scandium iodide, along with sodium iodide, when added to a modified form of mercury-vapor lamp, produces a form of metal halide lamp. This lamp is a white light source with high color rendering indexthat sufficiently resembles sunlight to allow good color-reproduction with TV cameras.HP Pavilion DV4-1014NR Battery

About 80 kg of scandium is used in metal halide lamps/light bulbs globally per year. The first scandium-based metal halide lamps were patented by General Electric and initially made in North America, although they are now produced in all major industrialized countries. HP Pavilion DV4-1014TX Battery

The radioactive isotope 46Sc is used in oil refineries as a tracing agent.[28] Scandium triflate is a catalytic Lewis acid used inorganic chemistry.[30]

Health and safety

Elemental scandium is considered non-toxic and little animal testing of scandium compounds has been done.HP Pavilion DV4-1015TX Battery

The median lethal dose (LD50) levels for scandium(III) chloride for rats have been determined as 4 mg/kg for intraperitoneal and 755 mg/kg for oral administration.[32] In the light of these results compounds of scandium should be handled as compounds of moderate toxicity.HP Pavilion DV4-1015TX Battery

Naturally occurring scandium (Sc) is composed of one stable isotope 45Sc. Twenty-four radioisotopes have been characterized with the most stable being 46Sc with ahalf-life of 83.8 days, 47Sc with a half-life of 3.35 days, and 48Sc with a half-life of 43.7 hours.HP Pavilion DV4-1016TX Battery

All of the remaining radioactive isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes, the least stable being 39Sc with a half-life shorter than 300 nanoseconds. The half-lives for isotopes with mass numbers less than 39 is unknown. HP Pavilion DV4-1017TX Battery

This element also has 10 meta states with the most stable being 44mSc (t½ 58.6 h).

The isotopes of scandium range in atomic weight from 36 u (36Sc) to 60 u (60Sc). The primary decay mode at masses lower than the only stable isotope, 45Sc, is Beta-plus or electron capture, and the primary mode at masses above it is beta-minus. HP Pavilion DV4-1018TX Battery

The primary decay products at atomic weights below 45Sc are calcium isotopes and the primary products from higher atomic weights are titanium isotopes.

As defined by IUPAC, rare earth elements or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium.HP Pavilion DV4-1019TX Battery

Scandium and yttrium are considered rare earth elements since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.

Despite their name, rare earth elements (with the exception of the radioactive promethium) are relatively plentiful in the Earth's crust, with cerium being the 25th most abundant element at 68 parts per million (similar to copper). HP Pavilion DV4-1020TX Battery

However, because of their geochemical properties, rare earth elements are typically dispersed and not often found in concentrated and economically exploitable forms. The few economically exploitable deposits are known as rare earth minerals.[3] It was the very scarcity of these minerals (previously called "earths") that led to the term "rare earth". HP Pavilion DV4-1020US Battery

The first such mineral discovered was gadolinite, acompound of cerium, yttrium, iron, silicon and other elements. This mineral was extracted from a mine in the village of Ytterby inSweden; many of the rare earth elements bear names derived from this location.HP Pavilion DV4-1021TX Battery

A table listing the seventeen rare earth elements, their atomic number and symbol, the etymology of their names, and their main usages (see also Lanthanide#Technological_applications) is provided here. Some of the rare earths are named for the scientists who discovered or elucidated their elemental properties, and some for their geographical discovery.HP Pavilion DV4-1022TX Battery

Discovery and early history

Rare earth elements became known to the world with the discovery of the black mineral "ytterbite" (renamed to gadolinite in 1800) by Lieutenant Carl Axel Arrheniusin 1787, at a quarry in the village of Ytterby, Sweden.HP Pavilion DV4-1023TX Battery

Arrhenius' "ytterbite" reached Johan Gadolin, a Royal Academy of Turku professor, and his analysis yielded an unknown oxide (earth) which he called Ytteria. Anders Gustav Ekeberg isolated beryllium from the gadolinite but failed to recognize other elements which the ore contained. HP Pavilion DV4-1024TX Battery

After this discovery in 1794 a mineral fromBastnäs near Riddarhyttan, Sweden, which was believed to be an iron-tungsten mineral, was re-examined by Jöns Jacob Berzelius and Wilhelm Hisinger. In 1803 they obtained a white oxide and called it ceria. Martin Heinrich Klaproth independently discovered the same oxide and called it ochroia.HP Pavilion DV4-1025TX Battery

Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and ytteria (the similarity of the rare earth metals' chemical properties made their separation difficult).HP Pavilion DV4-1026TX Battery

In 1839 Carl Gustav Mosander, an assistant of Berzelius, separated ceria by heating the nitrate and dissolving the product in nitric acid. He called the oxide of the soluble salt lanthana. It took him three more years to separate the lanthana further into didymia and pure lanthana. Didymia, although not further separable by Mosander's techniques was a mixture of oxides.HP Pavilion DV4-1027TX Battery

In 1842 Mosander also separated the ytteria into three oxides: pure ytteria, terbia and erbia (all the names are derived from the town name "Ytterby"). The earth giving pink salts he called terbium; the one which yielded yellow peroxide he called erbium.

So in 1842 the number of rare earth elements had reached six: yttrium, cerium, lanthanum, didymium, erbium and terbium.HP Pavilion DV4-1028TX Battery

Nils Johan Berlin and Marc Delafontaine tried also to separate the crude ytteria and found the same substances that Mosander obtained, but Berlin named (1860) the substance giving pink salts erbium and Delafontaine named the substance with the yellow peroxide terbium.HP Pavilion DV4-1028US Battery

This confusion led to several false claims of new elements, such as the mosandrium of J. Lawrence Smith, or the philippiumand decipium of Delafontaine.

There were no further discoveries for 30 years, and the element didymium was listed in the periodic table of elements with a molecular mass of 138. HP Pavilion DV4-1029TX Battery

In 1879 Delafontaine used the new physical process of optical-flame spectroscopy, and he found several new spectral lines in didymia. Also in 1879, the new element samariumwas isolated by Paul Émile Lecoq de Boisbaudran from the mineral samarskite.HP Pavilion DV4-1030EE Battery

The samaria earth was further separated by Lecoq de Boisbaudran in 1886 and a similar result was obtained by Jean Charles Galissard de Marignac by direct isolation from samarskite. They named the element gadolinium after Johan Gadolin, and its oxide was named "gadolinia".HP Pavilion DV4-1030EI Battery

Further spectroscopic analysis between 1886 and 1901 of samaria, ytteria, and samarskite by William Crookes, Lecoq de Boisbaudran and Eugène-Anatole Demarçay yielded several new spectroscopic lines that indicated the existence of an unknown element. The fractional crystallization of the oxides then yielded europium in 1901.HP Pavilion DV4-1030EJ Battery

In 1839 the third source for rare earths became available. This is a mineral similar to gadolinite, uranotantalum (now called "samarskite"). This mineral from Miassin the southern Ural Mountains was documented by Gustave Rose. The Russian chemist R.HP Pavilion DV4-1030EN Battery

Harmann proposed that a new element he called "ilmenium" should be present in this mineral, but later, Christian Wilhelm Blomstrand, Galissard de Marignac, and Heinrich Rose found only tantalum and niobium (columbium) in it.

The exact number of rare earth elements that existed was highly unclear, and a maximum number of 25 was estimated. HP Pavilion DV4-1030TX Battery

The use of X-ray spectra (obtained by X-ray crystallography) by Henry Gwyn Jeffreys Moseley made it possible to assign atomic numbers to the elements. Moseley found that the exact number of lanthanides had to be 15 and that element 61 had yet to be discovered.HP Pavilion DV4-1031TX Battery

Using these facts about atomic numbers from X-ray crystallography, Moseley also showed that hafnium (element 72) would not be a rare earth element. Moseley was killed in World War I in 1915, years before hafnium was discovered. Hence, the claim of Georges Urbain that he had discovered element 72 was untrue. HP Pavilion DV4-1032TX Battery

Hafnium is an element that lies in the periodic table immediately below zirconium, and hafnium and zirconium are very similar in their chemical and physical properties.

During the 1940s, Frank Spedding and others in the United States (during the Manhattan Project) developed the chemical ion exchange procedures for separating and purifying the rare earth elements. HP Pavilion DV4-1033TX Battery

This method was first applied to the actinides for separating plutonium-239 and neptunium, from uranium, thorium, actinium, and the other actinide rare earths in the materials produced in nuclear reactors. The plutonium-239 was very desirable because it is a fissile material.HP Pavilion DV4-1034TX Battery

The principal sources of rare earth elements are the minerals bastnäsite, monazite, and loparite and the lateritic ion-adsorption clays. Despite their high relative abundance, rare earth minerals are more difficult to mine and extract than equivalent sources of transition metals (due in part to their similar chemical properties), making the rare earth elements relatively expensive.HP Pavilion DV4-1035LA Battery

Their industrial use was very limited until efficient separation techniques were developed, such asion exchange, fractional crystallization and liquid-liquid extraction during the late 1950s and early 1960s.

Origin

Rare earth elements are heavier than iron and thus are produced by supernova nucleosynthesis or the s-process in asymptotic giant branch stars.HP Pavilion DV4-1035TX Battery

In nature,spontaneous fission of uranium-238 produces trace amounts of radioactive promethium, but most promethium is synthetically produced in nuclear reactors.

Geological distribution

Rare earth cerium is actually the 25th most abundant element in the Earth's crust, having 68 parts per million (about as common as copper). Only the highly unstable and radioactivepromethium "rare earth" is quite scarce.HP Pavilion DV4-1036TX Battery

The rare earth elements are often found together. The longest-lived isotope of promethium has a half life of 17.7 years, so the element only exists in nature in negligible amounts (approximately 572 g in the entire Earth's crust). Promethium is one of the two elements that do not have stable (non-radioactive) isotopes and are followed by (i.e. with higher atomic number) stable elements.HP Pavilion DV4-1037TX Battery

Due to lanthanide contraction, yttrium, which is trivalent, is of similar ionic size todysprosium and its lanthanide neighbors. Due to the relatively gradual decrease in ionic size with increasing atomic number, the rare earth elements have always been difficult to separate. HP Pavilion DV4-1038TX Battery

Even with eons of geological time, geochemical separation of the lanthanides has only rarely progressed much farther than a broad separation between light versus heavy lanthanides, otherwise known as the cerium and yttrium earths. This geochemical divide is reflected in the first two rare earths that were discovered, yttria in 1794 and ceria in 1803. HP Pavilion DV4-1039TX Battery

As originally found, each comprised the entire mixture of the associated earths. Rare earth minerals, as found, usually are dominated by one group or the other, depending upon which size-range best fits the structural lattice. Thus, among the anhydrous rare earth phosphates, it is the tetragonal mineral xenotime that incorporates yttrium and the yttrium earths, whereas the monoclinic monazite phase incorporates cerium and the cerium earths preferentially.HP Pavilion DV4-1040EE Battery

The smaller size of the yttrium group allows it a greater solid solubility in the rock-forming minerals that comprise the Earth's mantle, and thus yttrium and the yttrium earths show less enrichment in the Earth's crust relative to chondritic abundance, than does cerium and the cerium earths. HP Pavilion DV4-1040EI Battery

This has economic consequences: large ore bodies of the cerium earths are known around the world, and are being exploited. Corresponding orebodies for yttrium tend to be rarer, smaller, and less concentrated. Most of the current supply of yttrium originates in the "ion adsorption clay" ores of Southern China.HP Pavilion DV4-1040TX Battery

Some versions provide concentrates containing about 65% yttrium oxide, with the heavy lanthanides being present in ratios reflecting the Oddo-Harkins rule: even-numbered heavy lanthanides at abundances of about 5% each, and odd-numbered lanthanides at abundances of about 1% each. Similar compositions are found in xenotime or gadolinite.HP Pavilion DV4-1041TX Battery

Well-known minerals containing yttrium include gadolinite, xenotime, samarskite, euxenite, fergusonite, yttrotantalite, yttrotungstite, yttrofluorite (a variety offluorite), thalenite, yttrialite. Small amounts occur in zircon, which derives its typical yellow fluorescence from some of the accompanying heavy lanthanides. HP Pavilion DV4-1042TX Battery

Thezirconium mineral eudialyte, such as is found in southern Greenland, contains small but potentially useful amounts of yttrium. Of the above yttrium minerals, most played a part in providing research quantities of lanthanides during the discovery days. HP Pavilion DV4-1043TX Battery

Xenotime is occasionally recovered as a byproduct of heavy sand processing, but is not as abundant as the similarly recovered monazite (which typically contains a few percent of yttrium). Uranium ores from Ontario have occasionally yielded yttrium as a byproduct.HP Pavilion DV4-1044TX Battery

Well-known minerals containing cerium and the light lanthanides include bastnaesite, monazite, allanite, loparite, ancylite, parisite, lanthanite, chevkinite,cerite, stillwellite, britholite, fluocerite, and cerianite. Monazite (marine sands from Brazil, India, or Australia; rock from South Africa), bastnaesite (fromMountain Pass, California, or several localities in China), and loparite (Kola Peninsula, Russia) have been the principal ores of cerium and the light lanthanides.HP Pavilion DV4-1045TX Battery

In 2011, Yasuhiro Kato, a geologist at the University of Tokyo who led a study of Pacific Ocean seabed mud, published results indicating the mud could hold rich concentrations of rare earth minerals. The deposits, studied at 78 sites, came from "[h]ot plumes from hydrothermal vents pull[ing] these materials out of seawater and deposit[ing] them on the seafloor,HP Pavilion DV4-1046TX Battery

bit by bit, over tens of millions of years. One square patch of metal-rich mud 2.3 kilometers wide might contain enough rare earths to meet most of the global demand for a year, Japanese geologists report July 3 in Nature Geoscience." "I believe that rare earth resources undersea are much more promising than on-land resources," said Kato. "HP Pavilion DV4-1047TX Battery

oncentrations of rare earths were comparable to those found in clays mined in China. Some deposits contained twice as much heavy rare earths such as dysprosium, a component of magnets in hybrid car motors."[8]

Global rare earth production

Until 1948, most of the world's rare earths were sourced from placer sand deposits in India and Brazil.HP Pavilion DV4-1048TX Battery

Through the 1950s, South Africa took the status as the world's rare earth source, after large veins of rare earth bearing monazitewere discovered there.[9] Through the 1960s until the 1980s, the Mountain Pass rare earth mine in California was the leading producer.HP Pavilion DV4-1049TX Battery

Today, the Indian and South African deposits still produce some rare earth concentrates, but they are dwarfed by the scale of Chinese production. China now produces over 97% of the world's rare earth supply, mostly in Inner Mongolia,[10][11] even though it has only 37% of proven reserves.HP Pavilion DV4-1050 Battery

All of the world's heavy rare earths (such as dysprosium) come from Chinese rare earth sources such as the polymetallic Bayan Obo deposit. In 2010, the USGS released a study which found that the United States had 13 million metric tons of rare earth elements.HP Pavilion DV4-1050EE Battery

New demand has recently strained supply, and there is growing concern that the world may soon face a shortage of the rare earths.[15] In several years from 2009 worldwide demand for rare earth elements is expected to exceed supply by 40,000 tonnes annually unless major new sources are developed.HP Pavilion DV4-1050EL Battery

These concerns have intensified due to the actions of China, the predominant supplier. Specifically, China has announced regulations on exports and a crackdown on smuggling. On September 1, 2009, China announced plans to reduce its export quota to 35,000 tons per year in 2010–2015, ostensibly to conserve scarce resources and protect the environment.HP Pavilion DV4-1050EP Battery

On October 19, 2010 China Daily, citing an unnamed Ministry of Commerce official, reported that China will "further reduce quotas for rare earth exports by 30 percent at most next year to protect the precious metals from over-exploitation". At the end of 2010 China announced that the first round of export quotas in 2011 for rare earths would be 14,446 tons which was a 35% decrease from the previous first round of quotas in 2010.HP Pavilion DV4-1050ER Battery

China announced further export quotas on 14 July 2011 for the second half of the year with total allocation at 30,184 tons with total production capped at 93,800 tonnes.[21] In September 2011 China announced the halt in production of three of its eight major rare earth mines, responsible for almost 40% of China's total rare earth production.HP Pavilion DV4-1050TX Battery

As a result of the increased demand and tightening restrictions on exports of the metals from China, some countries are stockpiling rare earth resources. Searches for alternative sources in Australia, Brazil, Canada, South Africa, Greenland, and the United States are ongoing.HP Pavilion DV4-1051 Battery

Mines in these countries were closed when China undercut world prices in the 1990s, and it will take a few years to restart production as there are many barriers to entry.[17] One example is theMountain Pass mine in California, which is projected to reopen in 2011.HP Pavilion DV4-1051TX Battery

Other significant sites under development outside of China include the Nolans Project in Central Australia, the remote Hoidas Lake project in northern Canada, and the Mount Weld project in Australia.The Hoidas Lake project has the potential to supply about 10% of the $1 billion of REE consumption that occurs in North America every year.HP Pavilion DV4-1052 Battery

Vietnam signed an agreement in October 2010 to supply Japan with rare earths[29] from its northwestern Lai Châu Province.

Also under consideration for mining are sites such as Thor Lake in the Northwest Territories, various locations in Vietnam, and a site in southeast Nebraskain the US, where Quantum Rare Earth Development, a Canadian company, is currently conducting test drilling and economic feasibility studies toward opening a niobium mine.HP Pavilion DV4-1052TX Battery

Additionally, a large deposit of rare earth minerals was recently discovered in Kvanefjeld in southern Greenland.[32] Pre-feasibility drilling at this site has confirmed significant quantities of black lujavrite, which contains about 1% rare earth oxides (REO).[HP Pavilion DV4-1053 Battery

In early 2011, Australian mining company, Lynas, was reported to be "hurrying to finish" a US$230 million rare earth refinery on the eastern coast of Malaysia's industrial port of Kuantan. The plant would refine "slightly radioactive" ore - Lanthanide concentrate from the Mount Weld mine in Australia. HP Pavilion DV4-1053TX Battery

The ore would be trucked to Fremantle and transported by container ship to Kuantan. However, the Malaysian authorities confirmed that as of October 2011, Lynas was not given any permit to import any rare earth ore into Malaysia. Within two years, Lynas was said to expect the refinery to be able to meet nearly a third of the world's demand for rare earth materials, not counting China."HP Pavilion DV4-1054TX Battery

The Kuantan development brought renewed attention to the Malaysian town of Bukit Merah in Perak, where a rare-earth mine operated by a Mitsubishi Chemical subsidiary, Asian Rare Earth, closed in 1992 and left continuing environmental and health concerns.HP Pavilion DV4-1055TX Battery

In mid-2011, after protests, Malaysian government restrictions on the Lynas plant were announced. At that time, citing subscription-only Dow Jones Newswire reports, a Barronsreport said the Lynas investment was $730 million, and the projected share of the global market it would fill put at "about a sixth.HP Pavilion DV4-1070 Battery

An independent review was initiated by Malaysian Government and UN and conducted by IAEA between 29 May and 3 June 2011 to address concerns of radioactive hazards. The IAEA team was not able to identify any non-compliance with international radiation safety standards.[HP Pavilion DV4-1070EE Battery]

Another recently developed source of rare earths is electronic waste and other wastes that have significant rare earth components. New advances in recycling technology have made extraction of rare earths from these materials more feasible, and recycling plants are currently operating in Japan, where there is an estimated 300,000 tons of rare earths stored in unused electronics.HP Pavilion DV4-1070EF Battery

Significant quantities of rare earth oxides are found in tailings accumulated from 50 years of uranium ore, shale and loparite mining at Sillamäe, Estonia.[39] Due to the rising prices of rare earths, extraction of these oxides has become economically viable. The country currently exports around 3,000 tonnes per year, representing around 2% of world production.HP Pavilion DV4-1070ER Battery

Nuclear reprocessing is another potential source of rare earth or any other elements. Nuclear fission of uranium or plutonium produces a full range of elements, including all their isotopes. However, due to the radioactivity of many of these isotopes, it is unlikely that extracting them from the mixture can be done safely and economically.HP Pavilion DV4-1070ES Battery

Environmental considerations

Mining, refining, and recycling of rare earths have serious environmental consequences if not properly managed. A particular hazard is mildly radioactive slurrytailings resulting from the common occurrence of thorium and uranium in rare earth element ores.HP Pavilion DV4-1080EI Battery

Additionally, toxic acids are required during the refining process. Improper handling of these substances can result in extensive environmental damage. In May 2010, China announced a major, five-month crackdown on illegal mining in order to protect the environment and its resources. HP Pavilion DV4-1080EO Battery

This campaign is expected to be concentrated in the South, where mines – commonly small, rural, and illegal operations – are particularly prone to releasing toxic wastes into the general water supply. However, even the major operation in Baotou, in Inner Mongolia, where much of the world's rare earth supply is refined, has caused major environmental damage.HP Pavilion DV4-1080ES Battery

The Bukit Merah mine in Malaysia has been the focus of a US$100 million cleanup which is proceeding in 2011. "Residents blamed a rare earth refinery for birth defects and eight leukemia cases within five years in a community of 11,000 — after many years with no leukemia cases." HP Pavilion DV4-1090EO Battery

Seven of the leukemia victims died. After having accomplished the hilltop entombment of 11,000 truckloads of radioactively contaminated material, the project is expected to entail in summer, 2011, the removal of "more than 80,000 steel barrels of radioactive waste to the hilltop repository." HP Pavilion DV4-1090ES Battery

One of Mitsubishi's contractors for the cleanup is GeoSyntec, an Atlanta-based firm. Osamu Shimizu, a director of Asian Rare Earth, "said the company might have sold a few bags of calcium phosphate fertilizer on a trial basis as it sought to market byproducts" in reply to a former resident of Bukit Merah who said, "The cows that ate the grass [grown with the fertilizer] all died."HP Pavilion DV4-1100 Battery

In May 2011, after the Fukushima Daiichi nuclear disaster, widespread protests took place in Kuantan over the Lynas refinery and radioactive waste from it. The ore to be processed has very low levels of thorium, and Lynas founder and chief executive Nicholas Curtis said "There is absolutely no risk to public health." HP Pavilion DV4-1100EA Battery

T. Jayabalan, a doctor who says he has been monitoring and treating patients affected by the Mitsubishi plant, "is wary of Lynas's assurances. The argument that low levels of thorium in the ore make it safer doesn't make sense, he says, because radiation exposure is cumulative."HP Pavilion DV4-1101 Battery

Construction of the facility has been halted until an independent United Nations IAEA panel investigation is completed, which is expected by the end of June 2011.[45] New restrictions were announced by the Malaysian government in late June.[

IAEA panel investigation is completed and no construction has been halted.HP Pavilion DV4-1101TU Battery

Lynas is on budget and on schedule to start producing 2011. The IAEA report has concluded in a report issued by the nuclear watchdog Thursday June 2011 said it did not find any instance of "any non-compliance with international radiation safety standards" in the project. HP Pavilion DV4-1101TX Battery

Geo-political considerations

China has officially cited resource depletion and environmental concerns as the reasons for a nationwide crackdown on its rare earth mineral production sector. However, non-environmental motives have also been imputed to China's rare earth policy.HP Pavilion DV4-1102 Battery

According to The Economist, "Slashing their exports of rare-earth metals...is all about moving Chinese manufacturers up the supply chain, so they can sell valuable finished goods to the world rather than lowly raw materials." One possible example is the division of General Motors which deals with miniaturized magnet research, which shut down its US office and moved its entire staff toChina in 2006.HP Pavilion DV4-1102TU Battery

(It should be noted that China's export quota only applies to the metal but not products made from these metals such as magnets.

It was reported, but officially denied, that China instituted an export ban on shipments of rare earth oxides (but not alloys) to Japan on 22 September 2010, in response to the detainment of a Chinese fishing boat captain by the Japanese Coast Guard.HP Pavilion DV4-1102TX Battery

On September 2, 2010, a few days before the fishing boat incident,The Economist reported that "China...in July announced the latest in a series of annual export reductions, this time by 40% to precisely 30,258 tonnes."

The United States Department of Energy in its 2010 Critical Materials Strategy report identified dysprosium as the element that was most critical in terms of import reliance.HP Pavilion DV4-1103TU Battery

A 2011 report issued by the U.S. Geological Survey and U.S. Department of the Interior, “China’s Rare-Earth Industry," outlines industry trends within China and examines national policies that may guide the future of the country's production. The report notes that China’s lead in the production of rare-earth minerals has accelerated over the past two decades.HP Pavilion DV4-1103TX Battery

In 1990, China accounted for only 27% of such minerals. In 2009, world production was 132,000 metric tons; China produced 129,000 of those tons. According to the report, recent patterns suggest that China will slow the export of such materials to the world: “Owing to the increase in domestic demand, the Government has gradually reduced the export quota during the past several years.”HP Pavilion DV4-1104TU Battery

In 2006, China allowed 47 domestic rare-earth producers and traders and 12 Sino-foreign rare-earth producers to export. Controls have since tightened annually; by 2011, only 22 domestic rare-earth producers and traders and 9 Sino-foreign rare-earth producers were authorized. HP Pavilion DV4-1104TX Battery

The government’s future policies will likely keep in place strict controls: “According to China’s draft rare-earth development plan, annual rare-earth production may be limited to between 130,000 and 140,000 [metric tons] during the period from 2009 to 2015.HP Pavilion DV4-1105EF Battery

The export quota for rare-earth products may be about 35,000 [metric tons] and the Government may allow 20 domestic rare-earth producers and traders to export rare earths.”

The United States Geological Survey is actively surveying southern Afghanistan for rare earth deposits under the protection of United States military forces. HP Pavilion DV4-1105EM Battery

Since 2009 the USGS has conducted remote sensing surveys as well as fieldwork to verify Soviet claims that volcanic rocks containing rare earth metals exist in Helmand province near the village of Khanneshin. The USGS study team has located a sizable area of rocks in the center of an extinct volcano containing light rare earth elements including cerium and neodymium.HP Pavilion DV4-1105TU Battery

It has mapped 1.3 million metric tons of desirable rock, or about 10 years of supply at current demand levels. The Pentagon has estimated its value at about $7.4 billion.

Rare earth pricing

Rare earth elements are not exchange-traded in the same way that precious (for instance, gold and silver) or non-ferrous metals (such as nickel, tin, copper, andaluminum) are. HP Pavilion DV4-1105TX Battery

Instead they are sold on the private market, which makes their prices difficult to monitor and track. However, prices are published periodically on websites such as mineralprices.com.[56] The 17 elements are not usually sold in their pure form, but instead are distributed in mixtures of varying purity, e.g. "Neodymium metal ? 99.5%".HP Pavilion DV4-1106EE Battery

As such, pricing can vary based on the quantity and quality required by the end user's application.

The lanthanide or lanthanoid (IUPAC nomenclature) series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These fifteen elements, along with chemically similar scandium andyttrium, are often collectively known as the rare earth elements.HP Pavilion DV4-1106EM Battery

The informal chemical symbol Ln is used in general discussions of lanthanide chemistry. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell; lutetium, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen.HP Pavilion DV4-1106TX Battery

All of the lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.

The lanthanide elements are the group of elements with atomic number increasing from 57 (lanthanum) to 71 (lutetium).HP Pavilion DV4-1107TX Battery

They are termed lanthanide because the lighter elements in the series are chemically similar to lanthanum. Strictly speaking, both lanthanum and lutetium have been labeled as group 3 elements, because they both have a single valence electron in the d shell. However, both elements are often included in any general discussion of the chemistry of the lanthanide elements.HP Pavilion DV4-1108TX Battery

In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively.HP Pavilion DV4-1109TX Battery

This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).HP Pavilion DV4-1110EO Battery

Etymology

Together with scandium and yttrium, the trivial name "rare earths" is sometimes used to describe all the lanthanides. This name arises from the minerals from which they were isolated, which were uncommon oxide-type minerals.HP Pavilion DV4-1110TX Battery

However, the use of the name is deprecated by IUPAC, as the elements are neither rare in abundance nor "earths" (an obsolete term for water-insoluble strongly basic oxides of electropositive metals incapable of being smelted into metal using late 18th century technology) . HP Pavilion DV4-1111TX Battery

Cerium is the 26th most abundant element in the Earth's crust, neodymium is more abundant than gold and even thulium (the least common naturally occurring lanthanide) is more abundant than iodine. Despite their abundance, even the technical term "lanthanides" could be interpreted to reflect a sense of elusiveness on the part of these elements, HP Pavilion DV4-1112TX Battery

as it comes from the Greek ????????? (lanthanein), "to lie hidden". However, if not referring to their natural abundance, but rather to their property of "hiding" behind each other in minerals, this interpretation is in fact appropriate. THP Pavilion DV4-1113TX Battery

he etymology of the term must be sought in the first discovery of lanthanum, at that time a so-called new rare earth element "lying hidden" in a cerium mineral, and it is an irony that lanthanum was later identified as the first in an entire series of chemically similar elements and could give name to the whole series. The term lanthanide was probably introduced by Victor Goldschmidt in 1925.HP Pavilion DV4-1114NR Battery

Chemical compounds

The electronic structure of the lanthanide elements, with minor exceptions is [Xe]6s24fn. In their compounds, the 6s electrons are lost and the ions have the configuration [Xe]4fm.[8] The chemistry of the lanthanides differs from main group elements and transition metals because of the nature of the 4f orbitals. HP Pavilion DV4-1114TX Battery

These orbitals are "buried" inside the atom and are shielded from the atom's environment by the 4d and 5p electrons. As a consequence of this, the chemistry of the elements is largely determined by their size, which decreases gradually from 102 pm (La3+) with increasing atomic number to 86 pm (Lu3+), the so-called lanthanide contraction. HP Pavilion DV4-1115EF Battery

All the lanthanide elements exhibit the oxidation state +3. In addition Ce3+ can lose its single f electron to form Ce4+ with the stable electronic configuration of xenon. Also, Eu3+ can gain an electron to form Eu2+ with the f7 configuration which has the extra stability of a half-filled shell. Promethium is effectively a man-made element as all its isotopes are radioactive with half-lives of less than 20 y.HP Pavilion DV4-1115TX Battery

In terms of reduction potentials, the Ln0/3+ couples are nearly the same for all lanthanides, ranging from -1.99 (for Eu) to -2.35 V (for Pr). Thus, these metals are highly reducing, with reducing power similar to alkaline earth metals such as Mg (-2.36 V).HP Pavilion DV4-1116TX Battery

Separation of lanthanides

The similarity in ionic radius between adjacent lanthanide elements makes it difficult to separate them from each other in naturally occurring ores and other mixtures. Historically, the very laborious processes of cascading and fractional crystallization was used.HP Pavilion DV4-1117CA Battery

Because the lanthanide ions have slightly different radii, the lattice energy of their salts and hydration energies of the ions will be slightly different, leading to a small difference in solubility. Salts of the formula Ln(NO3)3.2NH4NO3.4H2O can be used. Industrially, the elements are separated from each other by solvent extraction.HP Pavilion DV4-1117TX Battery

Typically an aqueous solution of nitrates is extracted into kerosene containing tri-n-butylphosphate, (BunO)3PO. The strength of the complexes formed increases as the ionic radius decreases, so solubility in the organic phase increases. Complete separation can be achieved continuously by use of countercurrent exchange methods. HP Pavilion DV4-1118CA Battery

The elements can also be separated by ion-exchange chromatography, making use of the fact that the stability constant for formation of EDTA complexes increases for log K ? 15.5 for [La(EDTA)]- to log K ? 19.8 for [Lu(EDTA)]-.

Ln(III) compounds

The trivalent lanthanides mostly form ionic salts. HP Pavilion DV4-1118TX Battery

The trivalent ions are hard acceptors and form more stable complexes with oxygen-donor ligands than with nitrogen-donor ligands. The larger ions are 9-coordinate in aqueous solution, [Ln(H2O)9]3+ but the smaller ions are 8-coordinate, [Ln(H2O)8]3+. There is some evidence that the later lanthanides have more water molecules in the second coordination sphere.HP Pavilion DV4-1119TX Battery

Complexation with monodentate ligands is generally weak because it is difficult to displace water molecules from the first coordination sphere. Stronger complexes are formed with chelating ligands because of the chelate effect, such as the tetra-anion derived from 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA).HP Pavilion DV4-1120BR Battery

Ln(II) and Ln(IV) compounds

The most common divalent derivatives of the lanthanides are for Eu(II), which achieves a favorable f7 configuration. Divalent halide derivatives are known for all of the lanthanides. They are either conventional salts or are Ln(III) "electride"-like salts. The simple salts include YbI2, EuI2, and SmI2. HP Pavilion DV4-1120TX Battery

The electride-like salts, described as Ln2+, 2I-, e-, include NdI2, DyI2 and TmI2. Many of the iodides form soluble complexes with ethers, e.g. TmI2(dimethoxyethane)3.[11] Samarium(II) iodideis a useful reducing agent.

Ce(IV) in ceric ammonium nitrate is a useful oxidising agent. Otherwise tetravalent lanthanides are rare. The Ce(IV) is the exception owing to the tendency to form an unfilled f shell.HP Pavilion DV4-1120US Battery

Organometallic compounds

Lanthanide-carbon ? bonds are well known but they exhibit carbanion-like behavior, unlike transition metal organometallic compounds. Because of their large size, lanthanides tend to form more stable organometallic derivatives with bulky ligands to give compounds such as Ln[CH(SiMe3)3].HP Pavilion DV4-1121BR Battery

Similarly complexes ofcyclopentadienyl anion, e.g. [Ln(C5H5)3], are far less common than the corresponding pentamethylcyclopentadienyl, e.g. [Ln(C5Me5)3Cl]. Analogues of uranocene are derived from dilithiocyclooctatetraene, Li2C8H8. Organic lanthanide(II) compounds are also known, such as Cp*2Eu.HP Pavilion DV4-1121CA Battery

Magnetic and spectroscopic properties

All the trivalent lanthanide ions, except lutetium, have unpaired f electrons. However the magnetic moments deviate considerably from the spin-only values because of strong spin-orbit coupling.HP Pavilion DV4-1121TX Battery

The maximum number of unpaired electrons is 7, in Gd3+, with a magnetic moment of 7.94 B.M., but the largest magnetic moments, at 10.4-10.7 B.M., are exhibited by Dy3+ and Ho3+. However, in Gd3+ all the electrons have parallel spin and this property is important for the use of gadolinium complexes ascontrast reagent in MRI scans.HP Pavilion DV4-1122TX Battery

Crystal field splitting is rather small for the lanthanide ions and is less important than spin-orbit coupling in regard to energy levels.[13] Transitions of electrons between f orbitals are forbidden by the Laporte rule. Furthermore, because of the "buried" nature of the f orbitals, coupling with molecular vibrations is weak. HP Pavilion DV4-1123LA Battery

Consequently the spectra of lanthanide ions are rather weak and the absorption bands are similarly narrow. Glass containing holmium oxide and holmium oxide solutions (usually in perchloric acid) have sharp optical absorption peaks in the spectral range 200–900 nm and can be used as a wavelength calibration standard for optical spectrophotometers,[14] and are available commercially.HP Pavilion DV4-1123TX Battery

As f-f transitions are Laporte-forbidden, once an electron has been excited, decay to the ground state will be slow. This makes them suitable for use in lasers as it makes the population inversion easy to achieve. The Nd:YAG laser is one that is widely used. Europium-doped yttrium vanadate was the first red phosphor to enable the development of colour television screens.HP Pavilion DV4-1123US Battery

Lanthanide ions have notable luminescent properties due to their unique 4f orbitals. Laporte forbidden f-f transitions can be activated by excitation of a bound "antenna" ligand. This leads to sharp emission bands throughout the visible, NIR, and IR and relatively long luminescence lifetimes.HP Pavilion DV4-1124LA Battery

Geochemistry

The lanthanide contraction is responsible for the great geochemical divide that splits the lanthanides into light and heavy-lanthanide enriched minerals, the latter being almost inevitably associated with and dominated by yttrium. This divide is reflected in the first two "rare earths" that were discovered: yttria (1794) andceria (1803).HP Pavilion DV4-1124NR Battery

The geochemical divide has put more of the light lanthanides in the Earth's crust, but more of the heavy members in the Earth's mantle. The result is that although large rich ore-bodies are found that are enriched in the light lanthanides, correspondingly large ore-bodies for the heavy members are few. HP Pavilion DV4-1124TX Battery

The principal ores are monazite and bastnaesite. Monazite sands usually contain all the lanthanide elements, but the heavier elements are lacking in bastnaesite. The lanthanides obey the Oddo-Harkins rule - odd-numbered elements are less abundant than their even-numbered neighbours.HP Pavilion DV4-1125BR Battery

Three of the lanthanide elements have radioactive isotopes with long half-lives (138La, 147Sm and 176Lu) that can be used to date minerals and rocks from Earth, the Moon and meteorites.[18]

Biological effects

Compared to most other nondietary elements, non-radioactive lanthanides are classified as having low toxicity.HP Pavilion DV4-1125LA Battery

Technological applications

Lanthanide elements and their compounds have many uses but the quantities consumed are relatively small in comparison to other elements. About 15000 ton/year of the lanthanides are consumed as catalysts and in the production of glasses. HP Pavilion DV4-1125NR Battery

This 15000 tons corresponds to about 85% of the lanthanide production. From the perspective of value, however, applications in phosphors and magnets are more important.

Of the many technological devices, including superconductors, samarium-cobalt and neodymium-iron-boron high-flux rare-earth magnets, magnesium alloys, HP Pavilion DV4-1125TX Battery

electronic polishers, refining catalysts and hybrid car components (primarily batteries and magnets).Lanthanide ions are used as the active ions in luminescent materials used in optoelectronics applications, most notably the Nd:YAG laser. Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems.HP Pavilion DV4-1126LA Battery

Phosphors with lanthanide dopants are also widely used in cathode ray tube technology such as television sets. The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible. Yttrium iron garnet (YIG) spheres have been useful as tunable microwave resonators. HP Pavilion DV4-1126TX Battery

Lanthanide oxides are mixed with tungsten to improve their high temperature properties for welding, replacing thorium, which was mildly hazardous to work with. Many defense-related products also use lanthanide elements such as night vision goggles, rangefinders, the SPY-1 radar used in some Aegis equipped warships, and the propulsion system of Arleigh Burke-class destroyers all use rare earth elements in critical capacities. HP Pavilion DV4-1127LA Battery

Most lanthanides are widely used in lasers, and as (co-)dopants in doped-fiber optical amplifiers (e.g. Er-doped fiber amplfiers (EDFAs) which are used as repeaters in the terrestrial and submarine fiber-optic transmission links that carry internet traffic) . These elements deflect ultraviolet and infrared radiation and are commonly used in the production of sunglass lenses. HP Pavilion DV4-1127TX Battery

Other applications are summarized in the following table:

The complex [Gd(DOTA)]- is used in magnetic resonance imaging.

The group 3 elements are a group of chemical elements in the periodic table. This group, like other d-block groups, should contain four elements, but it is not agreed what elements belong in the group.HP Pavilion DV4-1128TX Battery

Scandium (Sc) and yttrium (Y) are always included, but the other two spaces are usually occupied by lanthanum (La) and actinium (Ac), or by lutetium (Lu) and lawrencium (Lr); less frequently, it is considered the group should be expanded to 32 elements (with all the lanthanides and actinides included) or contracted to contain only scandium and yttrium. HP Pavilion DV4-1129LA Battery

The group itself has not acquired a trivial name; however, scandium, yttrium and the lanthanides are sometimes called rare earth metals.

Three group 3 elements occur naturally, scandium, yttrium, and either lanthanum or lutetium. HP Pavilion DV4-1129TX Battery

Lanthanum continues the trend started by two lighter members in general chemical behavior, while lutetium behaves more similarly to yttrium. This is in accordance with the trend for period 6 transition metals to behave more similarly to their upper periodic table neighbors. HP Pavilion DV4-1130BR Battery

This trend is seen from hafnium, which is almost identical chemically to zirconium, to mercury, which is quite distant chemically fromcadmium, but still shares with it almost equal atomic size and other similar properties. They all are silvery-white metals under standard conditions. The fourth element, either actinium or lawrencium, has only radioactive isotopes. HP Pavilion DV4-1130TX Battery

Actinium, which occurs only in trace amounts, continues the trend in chemical behavior for metals that form tripositive ions with a noble gasconfiguration; synthetic lawrencium is calculated and partially shown to be more similar to lutetium and yttrium. So far, no experiments have been conducted to synthesize any element that could be the next group 3 element. HP Pavilion DV4-1131BR Battery

Unbiunium (Ubu), which could be considered a group 3 element if preceded by lanthanum and actinium, might be synthesized in the near future, being only three spaces away from the current heaviest element known, ununoctium.

In 1787, Swedish part-time chemist Carl Axel Arrhenius found a heavy black rock near the Swedish village of Ytterby, Sweden (part of the Stockholm Archipelago).HP Pavilion DV4-1131TX Battery

Thinking that it was an unknown mineral containing the newly discovered element tungsten,[2] he named it ytterbite.[note 2] Finnish scientist Johan Gadolin identified a new oxide or "earth" in Arrhenius' sample in 1789, and published his completed analysis in 1794;[3] in 1797, the new oxide was named yttria.HP Pavilion DV4-1132TX Battery

In the decades after French scientistAntoine Lavoisier developed the first modern definition of chemical elements, it was believed that earths could be reduced to their elements, meaning that the discovery of a new earth was equivalent to the discovery of the element within, which in this case would have been yttrium.HP Pavilion DV4-1133TX Battery

Until the early 1920s, the chemical symbol "Yt" was used for the element, after which "Y" came into common use.[5] Yttrium metal was first isolated in 1828 whenFriedrich Wöhler heated anhydrous yttrium(III) chloride with potassium to form metallic yttrium and potassium chloride.HP Pavilion DV4-1134TX Battery

In 1869, Russian chemist Dmitri Mendeleev published his periodic table, which had empty spaces for elements directly above and under yttrium. Mendeleev made several predictions on the upper neighbor of ytttrium, which he called eka-boron. was Swedish chemist Lars Fredrik Nilson and his team discovered the missing element in the minerals euxenite and gadolinite and prepared 2 grams of scandium(III) oxide of high purity.HP Pavilion DV4-1135BR Battery

He named it scandium, from the Latin Scandia meaning "Scandinavia". Chemical experiments on the element proved that Mendeleev's suggestions were correct; along with discovery and characterization of gallium andgermanium this proved the correctness of the whole periodic table and periodic law. HP Pavilion DV4-1135EE Battery

Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleverecognized the correspondence and notified Mendeleev.[11] Metallic scandium was produced for the first time in 1937 by electrolysis of a eutectic mixture, at 700–800 °C, of potassium, lithium, and scandium chlorides.HP Pavilion DV4-1135EI Battery

Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James [14] as an impurity in the mineral ytterbia, which was thought by most chemists to consist entirely of ytterbium. HP Pavilion DV4-1135TX Battery

Welsbach proposed the namescassiopeium for element 71 (after the constellation Cassiopeia) and aldebaranium (after the star Aldebaran) for the new name of ytterbium but these naming proposals were rejected, although many German scientists in the 1950s called the element 71 cassiopeium. HP Pavilion DV4-1136BR Battery

Urbain chose the names neoytterbium (Latin for "new ytterbium") for ytterbium and lutecium (from Latin Lutetia, for Paris) for the new element. The dispute on the priority of the discovery is documented in two articles in which Urbain and von Welsbach accuse each other of publishing results influenced by the published research of the other.HP Pavilion DV4-1136TX Battery

The Commission on Atomic Mass, which was responsible for the attribution of the names for the new elements, settled the dispute in 1909 by granting priority to Urbain and adopting his names as official ones. An obvious problem with this decision was that Urbain was one of the four members of the commission.HP Pavilion DV4-1137TX Battery

The separation of lutetium from ytterbium was first described by Urbain and the naming honor therefore went to him, but neoytterbium was eventually reverted back to ytterbium and in 1949, the spelling of element 71 was changed to lutetium.HP Pavilion DV4-1138TX Battery

Ironically, Charles James, who had modestly stayed out of the argument as to priority, worked on a much larger scale than the others, and undoubtedly possessed the largest supply of lutetium at the time.

Lawrencium was first synthesized by the Albert Ghiorso and his team on February 14, 1961, at the Lawrence Radiation Laboratory (now called the Lawrence Berkeley National Laboratory) at the University of California in Berkeley, California, United States. HP Pavilion DV4-1139TX Battery

The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californiumwith boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator (HILAC). The nuclide 257103 was originally reported, but then this was reassigned to 258103. HP Pavilion DV4-1140EK Battery

The team at the University of California suggested the name lawrencium (after Ernest O. Lawrence, the inventor of cyclotron particle accelerator) and the symbol "Lw", for the new element, but "Lw" was not adopted, and "Lr" was officially accepted instead. Nuclear-physics researchers in Dubna, Soviet Union (now Russia), reported in 1967 that they were not able to confirm American scientists' data on 257103.HP Pavilion DV4-1140GO Battery

Two years earlier, the Dubna team reported 256103. In 1992, the IUPACTrans-fermium Working Group officially recognized element 103, confirmed its naming as lawrencium, with symbol "Lr", and named the nuclear physics teams at Dubna and Berkeley as the co-discoverers of lawrencium.HP Pavilion DV4-1140TX Battery

So far, no experiments were conducted to synthesize any element that could be the next group 3 element; if lutetium and lawrencium are considered to be group 3 elements, then the next element in the group should be element 153, unpenttrium (Upt). However, after element 120, filling electronic configurations stops obeying Aufbau principle. HP Pavilion DV4-1141TX Battery

According to the principle, unpenttrium should have an electronic configuration of [Uuo]8s25g186f147d1[note 4] and filling the 5g-subshell should be stopped at element 138. However, the 7d-orbitals are calculated to start being filled on element 137, while the 5g-subshell closes only at element 144, after filling of 7d-subshell begins. HP Pavilion DV4-1142TX Battery

Therefore, it is hard to calculate which element should be the next group 3 element. Calculations suggest that unpentpentium (Upp, element 155) could also be the next group 3 element. If lanthanum and actinium are considered group 3 elements, then element 121, unbiunium (Ubu), should be the fifth group 3 element.HP Pavilion DV4-1143GO Battery

The element is calculated have electronic configuration of [Uuo]8s28p1/21, which is not associated with transition metals, without having a partially filled d-subshell. No experiments have been performed to create unpenttrium, unbiunium or any element that could be considered the next group 3 element; HP Pavilion DV4-1143TX Battery

however, unbiunium is the element with the lowest atomic number that has not been tried to be created and thus has chances to be, while unpenttrium, unpentpentium or any other element considered if preceded by lawrencium is very unlikely to be created due todrip instabilities that imply that the periodic table ends soon after the island of stability at unbihexium.HP Pavilion DV4-1144TX Battery

Characteristics

Like other groups, the members of this family show patterns in their electron configurations, especially the outermost shells, resulting in trends in chemical behavior. However, lawrencium is an exception, since its last electron is transferred to the 7p1/2subshell due to relativistic effects.HP Pavilion DV4-1144US Battery

Most of the chemistry has been observed only for the first three members of the group; chemical properties of both actinium and especially lawrencium are not well-characterized. The remaining elements of the group (scandium, yttrium, lutetium) are reactive metals with high melting points (1541 °C, 1526 °C, 1652 °C respectively). HP Pavilion DV4-1145BR Battery

They are usually oxidized to the +3 oxidation state, even through scandium, yttrium and lanthanum can form lower oxidation states. The reactivity of the elements, especially yttrium, is not always obvious due to the formation of a stable oxide layer, which prevents further reactions.HP Pavilion DV4-1145GO Battery

Scandium(III) oxide, yttrium(III) oxide and lutetium(III) oxide are white high-temperature-melting solids. The latter two exhibit weak basic character, but scandium(III) oxide is amphoteric.

Physical

Elements that show tripositive ions with electronic configuration of a noble gas (scandium, yttrium, lanthanum, actinium) show a clear trend in their physical properties, such as hardness. HP Pavilion DV4-1145TX Battery

At the same time, if group 3 is continued with lutetium and lawrencium, several trends are broken. For example, scandium and yttrium are both soft metals. Lanthanum is soft as well; all these elements have their outermost electrons quite far from the nucleus compared to the nuclei charges. HP Pavilion DV4-1146TX Battery

Due to the lanthanide contraction, lutetium, the last in the lanthanide series, has a significantly smaller atomic radius and a higher nucleus charge, thus making the extraction of the electrons from the atom to form metallic bonding more difficult, and thus making the metal harder.HP Pavilion DV4-1147CL Battery

However, lutetium suits the previous elements better in several other properties, such as melting and boiling points. Very little is known about lawrencium, and none of the properties above have been confirmed.

There is a dispute whether lanthanum and actinium or lutetium and lawrencium should be included into group 3. HP Pavilion DV4-1147TX Battery

Other d-block group are composed of four transition metals, and group 3 is sometimes considered to follow suit. Scandium and yttrium are always classified as transition metals, but it is controversial which elements should follow them in group 3, lanthanum and actinium or lutetium and lawrencium. HP Pavilion DV4-1148TX Battery

The current IUPAC definition of the term "lanthanoid" includes fifteen elements including both lanthanum and lutetium, and that of "transition element" applies to lanthanum and actinium, as well as lutetium but not lawrencium, since it does not correctly follow the Aufbau principle.HP Pavilion DV4-1149TX Battery

Normally, the 103rd electron would enter the d-subshell, but quantum mechanical research has found that the configuration is actually [Rn]7s25f147p1. due to relativistic effects. IUPAC thus has not recommended a specific format for the in-line-f-block periodic table, leaving the dispute open.HP Pavilion DV4-1150BR Battery

• Lanthanum and actinium are sometimes considered the remaining members of group 3. In their most commonly encountered tripositive ion forms, these elements do not possess any partially filled f-orbitals, thus continuing the scandium—yttrium—lanthanum—actinium trend, HP Pavilion DV4-1150EO Battery
• in which all the elements have relationship similar to that of elements of the calcium—strontium—barium—radium series, the elements' left neighbors in s-block. However, different behavior is observed in other d-block groups, especially in group 4, in which zirconium, hafnium and rutherfordium share similar chemical properties lacking a clear trend.HP Pavilion DV4-1150EO Battery
• In other tables, lutetium and lawrencium are classified as the remaining members of group 3. In these tables, lutetium and lawrencium end (or sometimes proceed) the lanthanide and actinide series, respectively. Since the f-shell is nominally full in the ground state electron configuration for both of these metals, HP Pavilion DV4-1150EP Battery
• they behave the more similarly to other period 6 and period 7 transition metals compared to the other lanthanides and actinides, and thus logically exhibit properties similar to those of scandium and yttrium.

Some tables, including the official IUPAC table[46] refer to all lanthanides and actinides by a marker in group 3.HP Pavilion DV4-1150ER Battery

This sometimes is believed to be is the inclusion of all 30 lanthanide and actinide elements as included in group 3. Lanthanides, as electropositive trivalent metals, all have a closely related chemistry, and all show many similarities to scandium and yttrium, but they also show additional properties characteristic of their partially-filled f-orbitals which are not common to scandium and yttrium.HP Pavilion DV4-1150ES Battery

Exclusion of all elements is based on properties of earlier actinides, which show a much wider variety of chemistry (for instance, in range ofoxidation states) within their series than the lanthanides, and comparisons to scandium and yttrium are even less useful.HP Pavilion DV4-1150TX Battery

] However, these elements are destabilized, and if they were stabilized to more closely match chemistry laws, they would be similar to lanthanides as well. Also, the later actinides fromcalifornium onwards behave more like the corresponding lanthanides, with only the valence +3 (and sometimes +2) shown.HP Pavilion DV4-1151TX Battery

Occurrence

Scandium, yttrium, and lutetium tend to occur together with other lanthanides (except promethium) tend to occur together in the Earth's crust, and are often harder to extract from their ores. The abundance of elements in Earth's crust for group 3 is quite low — HP Pavilion DV4-1152TX Battery

all the elements in the group are uncommon, the most abundant being yttrium with abundance of approximately 30 parts per million (ppm); the abundance of scandium is 16 ppm, while that of lutetium is about 0.5 ppm. For comparison, the abundance of copper is 50 ppm, that of chromium is 160 ppm, and that of molybdenum is 1.5 ppm. HP Pavilion DV4-1153TX Battery

Scandium is distributed sparsely and occurs in trace amounts in many minerals.Rare minerals from Scandinavia and Madagascar such as gadolinite, euxenite, and thortveitite are the only known concentrated sources of this element, the latter containing up to 45% of scandium in the form of scandium(III) oxide.HP Pavilion DV4-1154TX Battery

Yttrium has the same trend in occurrence places; it is found in lunar rock samples collected during the American Apollo Project in a relatively high content as well.

The principal commercially viable ore of lutetium is the rare earth phosphate mineral monazite, (Ce,La,etc.)PO4, which contains 0.003% of the element.HP Pavilion DV4-1155SE Battery

The main mining areas are China, United States, Brazil, India, Sri Lanka and Australia. Pure lutetium metalis one of the rarest and most expensive of the rare earth metals with the price about US$10,000/kg, or about one-fourth that ofgold.

Production

The most available element in group 3 is yttrium, with annual production of 8,900 tonnes in 2010.HP Pavilion DV4-1155TX Battery

Yttrium is mostly produced asoxide, by a single country, China (99%). Lutetium and scandium are also mostly obtained as oxides, and their annual production by 2001 was about 10 and 2 tonnes, respectively.

Group 3 elements are mined only as a byproduct from the extraction of other elements.HP Pavilion DV4-1156TX Battery

The metallic elements are extremely rare; the production of metallic yttrium is about a few tonnes, and that of scandium is in the order of 10 kg per year; production of lutetium is not calculated, but it is certainly small. The elements, after purification from other rare earth metals, are isolated as oxides; the oxides are converted to fluorides during reactions with hydrofluoric acid.HP Pavilion DV4-1157TX Battery

The resulting fluorides are reduced with alkaline earth metals or alloys of the metals; metallic calcium is used most frequently. For example:

Sc2O3 + 3 HF ? 2 ScF3 + 3 H2O

2 ScF3 + 3 Ca ? 3 CaF2 + 2 Sc

Biological chemistry

Group 3 elements are generally hard metals with low aqueous solubility, and have low availability to the biosphere. HP Pavilion DV4-1158TX Battery

No group 3 element has any documented biological role in living organisms. The radioactivity of the actinides generally makes them highly toxic to living cells, causing radiation poisoning.

Scandium has no biological role, but it is found in living organisms. Once reached a human, scandium concentrates in the liver and is a threat to it; some its compounds are possibly carcinogenic, even through in general scandium is not toxic.HP Pavilion DV4-1159TX Battery

Scandium is known to have reached the food chain, but in trace amounts only; a typical human takes in less than 0.1 micrograms per day. Once released into the environment, scandium gradually accumulates in soils, which leads to increased concentrations in soil particles, animals and humans. HP Pavilion DV4-1160ES Battery

Scandium is mostly dangerous in the working environment, due to the fact that damps and gases can be inhaled with air. This can cause lung embolisms, especially during long-term exposure. The element is known to damage cell membranes of water animals, causing several negative influences on reproduction and on the functions of the nervous system.HP Pavilion DV4-1160TX Battery

Yttrium has no known biological role, though it is found in most, if not all, organisms and tends to concentrate in the liver, kidney, spleen, lungs, and bones of humans. There is normally as little as 0.5 milligrams found within the entire human body; human breast milk contains 4 ppm.HP Pavilion DV4-1161TX Battery

Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. With up to 700 ppm, the seeds of woody plants have the highest known concentrations.

Lutetium has no biological role as well, but it is found even in the highest known organism, the humans, concentrating in bones, and to a lesser extent in the liver and kidneys.HP Pavilion DV4-1162TX Battery

Lutetium salts are known to cause metabolism and they occur together with other lanthanide salts in nature; the element is the least abundant in the human body of all lanthanides. Human diets have not been monitored for lutetium content, so it is not known how much the average human takes in, HP Pavilion DV4-1163TX Battery

but estimations show the amount is only about several micrograms per year, all coming from tiny amounts taken by plants. Soluble lutetium salts are mildly toxic, but insoluble ones are not.

The high radioactivity of lawrencium would make it highly toxic to living cells, causing radiation poisoning.HP Pavilion DV4-1164TX Battery

The effect results from poor shielding of nuclear charge (nuclear attractive force on electrons) by 4f electrons; the 6s electrons are drawn towards the nucleus, thus resulting in a smaller atomic radius.

In single-electron atoms, the average separation of an electron from the nucleus is determined by the subshell it belongs to, and decreases with increasing charge on the nucleus; this in turn leads to a decrease in atomic radius.HP Pavilion DV4-1165TX Battery

In multi-electron atoms, the decrease in radius brought about by an increase in nuclear charge is partially offset by increasing electrostatic repulsion among electrons. In particular, a "shielding effect" operates: i.e., as electrons are added in outer shells,HP Pavilion DV4-1166CA Battery

electrons already present shield the outer electrons from nuclear charge, making them experience a lower effective charge on the nucleus. The shielding effect exerted by the inner electrons decreases in the order s > p > d > f. Usually, as a particular subshell is filled in a period, atomic radius decreases. HP Pavilion DV4-1166TX Battery

This effect is particularly pronounced in the case of lanthanides, as the 4f subshell which is filled across these elements is not very effective at shielding the outer shell (n=5 and n=6) electrons. Thus the shielding effect is less able to counter the decrease in radius caused by increasing nuclear charge. This leads to "lanthanide contraction". HP Pavilion DV4-1167TX Battery

The ionic radius drops from 102 pm for cerium(III) to 86.1 pm for lutetium(III).

About 10% of the lanthanide contraction has been attributed to relativistic effects. HP Pavilion DV4-1168TX Battery

Effects

The results of the increased attraction of the outer shell electrons across the lanthanide period may be divided into effects on the lanthanide series itself including the decrease in ionic radii, and influences on the following or post-lanthanide elements.HP Pavilion DV4-1169TX Battery

Properties of the lanthanides

The ionic radii of the lanthanides decrease from 103(La3+) to 86 pm (Lu3+) in the lanthanide series.

Across the lanthanide series, electrons are added to the 4f shell. This first f shell is inside the full 5s and 5p shells (as well as the 6sshell in the neutral atom); the 4f shell is well-localized near the atomic nucleus and has little effect on chemical bonding.HP Pavilion DV4-1180BR Battery

The decrease in atomic and ionic radii does affect their chemistry, however. Without the lanthanide contraction, a chemical separation of lanthanides would be extremely difficult. However, this contraction makes the chemical separation of period 5 and period 6 transition metals of the same group rather difficult.HP Pavilion DV4-1190BR Battery

There is a general trend of increasing Vickers hardness, Brinell hardness, density and melting point from cerium to lutetium (with ytterbium being the most notable exception). Lutetium is the hardest and densest lanthanide and has the highest melting point.HP Pavilion DV4-1190EA Battery

Influence on the post-lanthanides

The elements following the lanthanides in the periodic table are influenced by the lanthanide contraction. The radii of the period-6 transition metals are smaller than would be expected if there were no lanthanides, and are in fact very similar to the radii of the period-5 transition metals, since the effect of the additional electron shell is almost entirely offset by the lanthanide contraction.HP Pavilion DV4-1190EJ Battery

For example, the atomic radii of the metal zirconium, Zr, (a period-5 transition element) is 159 pm and that of hafnium, Hf, (the corresponding period-6 element) is 156 pm. The ionic radius of Zr4+ is 79 pm and that of Hf4+ is 78 pm. The radii are very similar even though the number of electrons increases from 40 to 72 and theatomic mass increases from 91.22 to 178.49 g/mol. HP Pavilion DV4-1190EL Battery

The increase in mass and the unchanged radii lead to a steep increase in density from 6.51 to 13.35 g/cm3.

Zirconium and hafnium therefore have very similar chemical behaviour, having closely similar radii and electron configurations. Radius-dependent properties such aslattice energies, solvation energies, and stability constants of complexes are also similar.HP Pavilion DV4-1198ER Battery

Because of this similarity hafnium is found only in association with zirconium, which is much more abundant, and was discovered as a separate element 134 years later (in 1923) than zirconium (discovered in 1789).HP Pavilion DV4-1199EA Battery,HP Pavilion DV4-1199EE Battery,HP Pavilion DV4-1199EF Battery,HP Pavilion DV4-1199EO Battery,HP Pavilion DV4-1199EP Battery,HP Pavilion DV4-1199ER Battery,HP Pavilion DV4-1199ES Battery,HP Pavilion DV4-1199ET Battery,HP Pavilion DV4-1200 CTO Battery,HP Pavilion DV4-1200 Battery