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Group 3 is the first group of
transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...
s in the
periodic table The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ch ...
. This group is closely related to the
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides ( yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silv ...
s. Although some controversy exists regarding the composition and placement of this group, it is generally agreed among those who study the matter that this group contains the four elements
scandium Scandium is a chemical element with the symbol Sc and atomic number 21. It is a silvery-white metallic d-block element. Historically, it has been classified as a rare-earth element, together with yttrium and the Lanthanides. It was discovered in ...
(Sc),
yttrium Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a " rare-earth element". Yttrium is almost always found in co ...
(Y), lutetium (Lu), and lawrencium (Lr); this composition has also been suggested by a 2021 IUPAC provisional report studying the problem. The group is also called the scandium group or scandium family after its lightest member. The chemistry of the group 3 elements is typical for early transition metals: they all essentially have only the group
oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
of +3 as a major one, and like the preceding main-group metals are quite electropositive and have a less rich coordination chemistry. Due to the effects of the
lanthanide contraction The lanthanide contraction is the greater-than-expected decrease in atomic radii/ionic radii of the elements in the lanthanide series from atomic number 57, lanthanum, to 71, lutetium, which results in smaller than otherwise expected atomic radii ...
, yttrium and lutetium are very similar in properties. Yttrium and lutetium have essentially the chemistry of the heavy lanthanides, but scandium shows several differences due to its small size. This is a similar pattern to those of the early transition metal groups, where the lightest element is distinct from the very similar next two. All the group 3 elements are rather soft, silvery-white metals, although their hardness increases with atomic number. They quickly tarnish in air and react with water, though their reactivity is masked by the formation of an oxide layer. The first three of them occur naturally, and especially yttrium and lutetium are almost invariably associated with the
lanthanide The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yt ...
s due to their similar chemistry. Lawrencium is strongly
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
: it does not occur naturally and must be produced by artificial synthesis, but its observed and theoretically predicted properties are consistent with it being a heavier homologue of lutetium. None of the group 3 elements have any biological role. Historically, sometimes
lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between l ...
(La) and
actinium Actinium is a chemical element with the symbol Ac and atomic number 89. It was first isolated by Friedrich Oskar Giesel in 1902, who gave it the name ''emanium''; the element got its name by being wrongly identified with a substance ...
(Ac) were included in the group instead of lutetium and lawrencium, because the
electron configuration In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon ato ...
s of many of the rare earths were initially measured wrongly. This version of group 3 is still commonly found in textbooks, but most chemists and physicists who have published on the issue are against it. Some authors attempt to compromise between the two formats by leaving the spaces below yttrium blank, but this leaves the exact composition of group 3 unclear. __TOC__


Dispute on composition

Published periodic tables show variation regarding the heavier members of group 3, which begins with scandium and yttrium. They are commonly shown as lanthanum and actinium, but there is significant physical and chemical evidence that this is incorrect, and that the correct elements in those places are lutetium and lawrencium. A third form of group 3 exists, in which the spaces below yttrium are left blank, and 15 elements occur in each f-block row (lanthanum to lutetium, and actinium to lawrencium). It is used by some practitioners of the specialized branch of relativistic quantum mechanics concerned with the properties of superheavy elements, but there is confusion in the literature about the group 3 composition that it results in. Chemical, physical, and electronic concerns have been used to discuss the problem, but the chemist and philosopher of science
Eric Scerri Eric R. Scerri is a chemist, writer and philosopher of science of Maltese origin. He is a lecturer at the University of California, Los Angeles; and the founder and editor-in-chief of '' Foundations of Chemistry'', an international peer reviewed ...
considers such arguments inconclusive, pointing to cases where different properties favour different compositions of group 3.Scerri, pp. 392−401 Early investigators measuring the electron configurations of the rare earth elements concluded that they mostly had the configuration f''x''−1d1s2 with few exceptions. This suggested that lanthanum ( ed16s2) was the first 5d element and so that group 3 should be Sc-Y-La-Ac; fourteen f-block elements then follow, with lutetium as the last 4f element completing the 4f subshell. This placement was generally adopted in the 1940s as electron configurations became the basis for placing elements on the periodic table, and has been supported more recently by chemist Laurence Lavelle on the grounds that lanthanum and actinium ( nd17s2) indeed both lack f-electrons and therefore should not be considered as f-block elements. However, later measurements proved that in fact most of the lanthanides and the actinides have the configuration f''x''s2, with only a few (La, Ce, Gd, Lu; Ac, Pa, U, Np, Cm) having the old configuration. In particular, the 4f subshell actually finishes filling at ytterbium ( ef146s2) and so lutetium ( ef145d16s2) appears as an equally valid candidate to lanthanum ( ed16s2) for being the first 5d element. According to chemist and chemical historian William B. Jensen, this supports treating lanthanum and actinium ( nd17s2) as exceptions to the Madelung rule, where a d-electron replaces the idealised f-electron, exactly like what happens for thorium ( nd27s2) that is unanimously regarded as an f-block element despite also lacking an f-electron. Consequently, after the corrected configurations became known, Lev Landau and Evgeny Lifshitz pointed out in 1948 that the revised configurations indicated that lutetium was a d-block and not an f-block element; subsequently, many authors rediscovered the recommended change and applied it to all relevant elements, advocating that lutetium and lawrencium should replace lanthanum and actinium in group 3. Most authors writing on the group 3 problem support the Sc-Y-Lu-Lr form, but many textbooks continued to show Sc-Y-La-Ac. In 2015, the
International Union of Pure and Applied Chemistry The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
(IUPAC) began a project to decide if group 3 should be Sc-Y-La-Ac or Sc-Y-Lu-Lr: it was chaired by Scerri and included (among others) Jensen and Lavelle. It considered the question to be "of considerable importance" for chemists, physicists, and students, noting that the variation in published periodic tables on this point typically puzzled students and instructors. The IUPAC project released a provisional report in 2021. It concluded that the group 3 dispute cannot be decided by any objective means and that that made it more important for IUPAC to decide it as a matter of convention. According to the report, assigning electron configurations to atoms, and similarly assigning elements to blocks, represents an approximation: it makes the point that thorium is universally classified as an f-block element even though it lacks f-electrons. The report points out that if lanthanum and actinium are included in group 3, then the d-block must be split "into two highly uneven portions"; whereas if lutetium and lawrencium are included in group 3, no such split is required. It also points out that if the spaces below yttrium are left blank, then 15 elements occur in the f-block rows, even though by quantum mechanics an f-subshell can accommodate at most 14 electrons. Therefore, the report suggested considering scandium, yttrium, lutetium, and lawrencium as the group 3 elements. The reasons given were to display all elements in order of increasing atomic number, avoid the d-block split, and to have the blocks follow the widths quantum mechanics demands of them (2, 6, 10, and 14): no other possible version achieves all three. The report noted that some practitioners of a specialised branch of relativistic quantum mechanics concerned with the properties of superheavy elements uphold grouping together 15 rather than 14 f-block elements, but it considered that to be "interest-dependence" and stated that such findings "should not be imposed on the majority of users of the periodic table".


History

The discovery of the group 3 elements is inextricably tied to that of the rare earths, with which they are universally associated in nature. In 1787, Swedish part-time chemist Carl Axel Arrhenius found a heavy black rock near the Swedish village of
Ytterby Ytterby () is a village on the Swedish island of Resarö, in Vaxholm Municipality in the Stockholm archipelago. Today the residential area is dominated by suburban homes. The name of the village translates to "outer village". Ytterby is per ...
, Sweden (part of the Stockholm Archipelago). Thinking that it was an unknown mineral containing the newly discovered element
tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...
, Emsley 2001, p. 496 he named it
ytterbite Gadolinite, sometimes known as ytterbite, is a silicate mineral consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula . It is called gadolinite-(Ce) or gadolinite-(Y), depending on ...
. Finnish scientist Johan Gadolin identified a new oxide or "
earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
" in Arrhenius' sample in 1789, and published his completed analysis in 1794; in 1797, the new oxide was named ''yttria''.Greenwood and Earnshaw, p. 944 In the decades after French scientist
Antoine Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (
chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical compounds, chemical elements canno ...
s, 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''. Until the early 1920s, the chemical symbol "Yt" was used for the element, after which "Y" came into common use. Yttrium metal, albeit impure, was first prepared in 1828 when
Friedrich Wöhler Friedrich Wöhler () FRS(For) Hon FRSE (31 July 180023 September 1882) was a German chemist known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the fi ...
heated anhydrous
yttrium(III) chloride Yttrium(III) chloride is an inorganic compound of yttrium and chloride. It exists in two forms, the hydrate (YCl3(H2O)6) and an anhydrous form (YCl3). Both are colourless solids that are highly soluble in water and deliquescent. Structure Sol ...
with
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
to form metallic yttrium and
potassium chloride Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt ...
. In fact, Gadolin's yttria proved to be a mixture of many metal oxides, that started the history of the discovery of the rare earths. In 1869, Russian chemist
Dmitri Mendeleev Dmitri Ivanovich Mendeleev (sometimes transliterated as Mendeleyev or Mendeleef) ( ; russian: links=no, Дмитрий Иванович Менделеев, tr. , ; 8 February Old_Style_and_New_Style_dates">O.S._27_January.html" ;"title="O ...
published his periodic table, which had an empty space for an element above yttrium. Mendeleev made several predictions on this hypothetical element, which he called ''eka-boron''. By then, Gadolin's yttria had already been split several times; first by Swedish chemist Carl Gustaf Mosander, who in 1843 had split out two more earths which he called ''terbia'' and ''erbia'' (splitting the name of Ytterby just as yttria had been split); and then in 1878 when Swiss chemist Jean Charles Galissard de Marignac split terbia and erbia themselves into more earths. Among these was ytterbia (a component of the old erbia), which Swedish chemist Lars Fredrik Nilson successfully split in 1879 to reveal yet another new element. He named it scandium, from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
''Scandia'' meaning "Scandinavia". Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized the correspondence and notified Mendeleev. Chemical experiments on scandium proved that Mendeleev's suggestions were correct; along with discovery and characterization of
gallium Gallium is a chemical element with the Symbol (chemistry), symbol Ga and atomic number 31. Discovered by France, French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in boron group, group 13 of the periodic table and is similar to ...
and
germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors ...
this proved the correctness of the whole periodic table and
periodic law Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element. They were discovered by the Russian chemist Dmitri Mendeleev in the year 1863. Major periodic trends include atom ...
. Metallic scandium was produced for the first time in 1937 by
electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...
of a eutectic mixture, at 700–800 °C, of
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
,
lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense soli ...
, and
scandium chloride Scandium(III) chloride is the inorganic compound with the formula ScCl3. It is a white, high-melting ionic compound, which is deliquescent and highly water-soluble. This salt is mainly of interest in the research laboratory. Both the anhydrous f ...
s. Scandium exists in the same ores that yttrium had been discovered from, but is much rarer and probably for that reason had eluded discovery. The remaining component of Marignac's ytterbia also proved to be a composite. In 1907, French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James all independently discovered a new element within ytterbia. Welsbach proposed the name ''cassiopeium'' for his new element (after Cassiopeia), whereas Urbain chose the name ''lutecium'' (from Latin Lutetia, for Paris). 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. In 1909, the Commission on Atomic Mass, which was responsible for the attribution of the names for the new elements, granted 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. In 1949, the spelling of element 71 was changed to lutetium. Later work connected with Urbain's attempts to further split his lutecium however revealed that it had only contained traces of the new element 71, and that it was only von Welsbach's cassiopeium that was pure element 71. For this reason many German scientists continued to use the name ''cassiopeium'' for the element until the 1950s. 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. Lutetium was the last of the stable rare earths to be discovered. Over a century of research had split the original yttrium of Gadolin into yttrium, scandium, lutetium, and seven other new elements. Lawrencium is the only element of the group that does not occur naturally. It was probably first synthesized by Albert Ghiorso and his team on February 14, 1961, at the Lawrence Radiation Laboratory (now called the
Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States national laboratory that is owned by, and conducts scientific research on behalf of, the United States Department of Energy. Located in ...
) at the
University of California The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, University of California, Irvine, Irvine, University of Califor ...
in
Berkeley, California Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and E ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
. The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element
californium Californium is a radioactive chemical element with the symbol Cf and atomic number 98. The element was first synthesized in 1950 at Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding c ...
with
boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the '' boron group'' it has t ...
-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator (HILAC). The
nuclide A nuclide (or nucleide, from atomic nucleus, nucleus, also known as nuclear species) is a class of atoms characterized by their number of protons, ''Z'', their number of neutrons, ''N'', and their nuclear energy state. The word ''nuclide'' was co ...
257103 was originally reported. The team at the University of California suggested the name ''lawrencium'' (after
Ernest O. Lawrence Ernest Orlando Lawrence (August 8, 1901 – August 27, 1958) was an American nuclear physicist and winner of the Nobel Prize in Physics in 1939 for his invention of the cyclotron. He is known for his work on uranium-isotope separation fo ...
, the inventor of
cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Jan ...
particle accelerator) and the symbol "Lw", for the new element; IUPAC accepted their discovery, but changed the symbol to "Lr". In 1965, nuclear-physics researchers in
Dubna Dubna ( rus, Дубна́, p=dʊbˈna) is a town in Moscow Oblast, Russia. It has a status of ''naukograd'' (i.e. town of science), being home to the Joint Institute for Nuclear Research, an international nuclear physics research center and one o ...
,
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
(now
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
) reported 256103, in 1967, they reported that they were not able to confirm American scientists' data on 257103, and proposed the name "rutherfordium" for the new element. The Dubna group criticised the IUPAC approval of the Berkeley group's discovery as having been hasty. In 1971, the Berkeley group did a whole series of experiments aimed at measuring the nuclear decay properties of element 103 isotopes, in which all previous results from Berkeley and Dubna were confirmed, except that the initial 257103 isotope reported at Berkeley in 1961 turned out to have been 258103. (Note: for Part I see Pure Appl. Chem., Vol. 63, No. 6, pp. 879–886, 1991) In 1992, the
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
Trans-fermium Working Group named the nuclear physics teams at Dubna and Berkeley as the co-discoverers of element 103. When IUPAC made the final decision of the naming of the elements beyond 100 in 1997, it decided to keep the name "lawrencium" and symbol "Lr" for element 103 as it had been in use for a long time by that point. The name "rutherfordium" was assigned to the following element 104, which the Berkeley team had proposed it for.


Characteristics


Chemical

Like other groups, the members of this family show patterns in their electron configurations, especially the outermost shells, resulting in trends in chemical behavior. Due to
relativistic effects Relativistic quantum chemistry combines relativistic mechanics with quantum chemistry to calculate elemental properties and structure, especially for the heavier elements of the periodic table. A prominent example is an explanation for the color of ...
that become important for high atomic numbers, lawrencium's configuration has an irregular 7p occupancy instead of the expected 6d, but the regular nf146d17s2 configuration is low enough in energy that no significant difference from the rest of the group is observed or expected. Most of the chemistry has been observed only for the first three members of the group; chemical properties of lawrencium are not well-characterized, but what is known and predicted matches its position as a heavier homolog of lutetium. The remaining elements of the group (scandium, yttrium, lutetium) are quite electropositive. They are reactive metals, although this is not obvious due to the formation of a stable oxide layer which prevents further reactions. The metals burn easily to give the oxides,Greenwood and Earnshaw, pp. 964–5 which are white high-melting solids. They are usually oxidized to the +3 oxidation state, in which they form mostly ionic compounds and have a mostly cationic aqueous chemistry. In this way they are similar to the lanthanides, although they lack the involvement of f orbitals that characterises the chemistry of the 4f elements lanthanum through ytterbium. The stable group 3 elements are thus often grouped with the 4f elements as the so-called rare earths. Typical transition-metal properties are mostly absent from this group, as they are for the heavier elements of groups 4 and 5: there is only one typical oxidation state and the coordination chemistry is not very rich (though high coordination numbers are common due to the large size of the M3+ ions). This said, low-oxidation state compounds may be prepared and some
cyclopentadienyl Cyclopentadienyl can refer to * Cyclopentadienyl anion, or cyclopentadienide, ** Cyclopentadienyl ligand * Cyclopentadienyl radical, • * Cyclopentadienyl cation, See also * Pentadienyl {{Chemistry index ...
chemistry is known. The chemistries of group 3 elements are thus mostly distinguished by their atomic radii: yttrium and lutetium are very similar, but scandium stands out as the least basic and the best complexing agent, approaching
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...
in some properties. They naturally take their places together with the rare earths in a series of trivalent elements: yttrium acts as a rare earth intermediate between
dysprosium Dysprosium is the chemical element with the symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanide ...
and
holmium Holmium is a chemical element with the symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like a lot of oth ...
in basicity; lutetium as less basic than the 4f elements and the least basic of the lanthanides; and scandium as a rare earth less basic than even lutetium. Scandium oxide is amphoteric; lutetium oxide is more basic (although it can with difficulty be made to display some acidic properties), and yttrium oxide is more basic still. Salts with strong acids of these metals are soluble, whereas those with weak acids (e.g. fluorides, phosphates, oxalates) are sparingly soluble or insoluble.


Physical

The trends in group 3 follow those of the other early d-block groups and reflect the addition of a filled f-shell into the core in passing from the fifth to the sixth period. For example, scandium and yttrium are both soft metals. But because of the
lanthanide contraction The lanthanide contraction is the greater-than-expected decrease in atomic radii/ionic radii of the elements in the lanthanide series from atomic number 57, lanthanum, to 71, lutetium, which results in smaller than otherwise expected atomic radii ...
, the expected increase in atomic radius from yttrium to lutetium is reversed; lutetium atoms are slightly smaller than yttrium atoms, but are heavier and have a higher nuclear charge. This makes the metal more dense, and also harder because the extraction of the electrons from the atom to form
metallic bonding Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be des ...
becomes more difficult. All three metals have similar melting and boiling points. Very little is known about lawrencium, but calculations suggest it continues the trend of its lighter congeners toward increasing density. Scandium, yttrium, and lutetium all crystallize in the hexagonal close-packed structure at room temperature,Greenwood and Earnshaw, pp. 946–8 and lawrencium is expected to do the same. The stable members of the group are known to change structure at high temperature. In comparison with most metals, they are not very good conductors of heat and electricity because of the low number of electrons available for metallic bonding.


Occurrence

Scandium, yttrium, and lutetium tend to occur together with the other lanthanides (except short-lived
promethium Promethium is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time. Promethium is one of onl ...
) in the Earth's crust, and are often harder to extract from their ores. The
abundance of elements in Earth's crust The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%). Estimates of elemental abundance are dif ...
for group 3 is quite low—all the elements in the group are uncommon, the most abundant being yttrium with abundance of approximately 30 
parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, th ...
(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. Scandium is distributed sparsely and occurs in trace amounts in many
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
s. Rare minerals from Scandinavia and
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
such as
gadolinite Gadolinite, sometimes known as ytterbite, is a silicate mineral consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula . It is called gadolinite-(Ce) or gadolinite-(Y), depending o ...
, euxenite, and
thortveitite Thortveitite is a rare mineral consisting of scandium yttrium silicate (Sc,Y)2Si2O7. It is the primary source of scandium. Occurrence is in granitic pegmatites. It was named after Olaus Thortveit, a Norwegian engineer. It is grayish-green, bla ...
are the only known concentrated sources of this element, the latter containing up to 45% of scandium in the form of scandium(III) oxide. Yttrium has the same trend in occurrence places; it is found in lunar rock samples collected during the
American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...
Apollo Project in a relatively high content as well. The principal commercially viable ore of lutetium is the rare-earth
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...
mineral
monazite Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the ceriu ...
, (Ce,La,etc.)PO4, which contains 0.003% of the element. The main mining areas are
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
,
Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
and
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
. Pure lutetium
metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
is 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 of
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
.


Production

The most available element in group 3 is yttrium, with annual production of 8,900 
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s in 2010. Yttrium is mostly produced as
oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
, 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. They are not often produced as the pure metals; 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. The resulting fluorides are reduced with
alkaline earth metal The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).. The elements have very similar properties: they are all ...
s or alloys of the metals; metallic
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
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 metals have low availability to the biosphere. Scandium, yttrium, and lutetium have no documented biological role in living organisms. The high radioactivity of lawrencium would make it highly toxic to living cells, causing radiation poisoning. Scandium concentrates in the liver and is a threat to it; some of its compounds are possibly
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
ic, even though in general scandium is not toxic. 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. 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. Yttrium 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 Breast milk (sometimes spelled as breastmilk) or mother's milk is milk produced by mammary glands located in the breast of a human female. Breast milk is the primary source of nutrition for newborns, containing fat, protein, carbohydrates ( la ...
contains 4 ppm. Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with
cabbage Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.&n ...
having the largest amount. Emsley 2001, pp. 495–498 With up to 700 ppm, the seeds of woody plants have the highest known concentrations. Lutetium concentrates in bones, and to a lesser extent in the liver and kidneys. 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, 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. Emsley 2001, p. 240


Notes


References


Bibliography

* * {{DEFAULTSORT:Group 03 Groups (periodic table)