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2 décembre 2011 5 02 /12 /décembre /2011 03:06

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

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