Group 3 element

Group 3 is a group of 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. 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. When the group is understood to contain all of the lanthanides, its trivial name is the rare-earth metals.

Three group 3 elements occur naturally: scandium, yttrium, and either lanthanum or lutetium. Lanthanum continues the trend started by two lighter members in general chemical behavior, while lutetium behaves more similarly to yttrium. While the choice of lutetium would be in accordance with the trend for period 6 transition metals to behave more similarly to their upper periodic table neighbors, the choice of lanthanum is in accordance with the trends in the s-block, which the group 3 elements are chemically more similar to. They all are silvery-white metals under standard conditions. The fourth element, either actinium or lawrencium, has only radioactive isotopes. Actinium, which occurs only in trace amounts, continues the trend in chemical behavior for metals that form tripositive ions with a noble gas configuration; 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. Unbiunium (Ubu), which could be considered a group 3 element if preceded by lanthanum and actinium, might be synthesized in the near future, it being only three spaces away from the current heaviest element known, oganesson.

Group 3 in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
IUPAC group number 3
Name by element scandium group
CAS group number
(US, pattern A-B-A)
IIIB
old IUPAC number
(Europe, pattern A-B)
IIIA

↓ Period
4
Scandium crystals
Scandium (Sc)
21 Transition metal
5
Yttrium crystals
Yttrium (Y)
39 Transition metal
6
Piece of lanthanum metal
Lanthanum (La*)
57 Lanthanide
7 Actinium (Ac*)
89 Actinide

* Whether the elements lutetium (Lu) and lawrencium (Lr), in period 6 and 7, are in group 3 is disputed. The grouping used in this article places La and Ac in group 3, which is the most common form. For other groupings, see group 3 borders.


Legend
primordial element
synthetic element
Atomic number color:
black=solid

History

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).[1] Thinking that it was an unknown mineral containing the newly discovered element tungsten,[2] he named it ytterbite.[note 1] 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.[4] In the decades after French scientist Antoine 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.[note 2] 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 when Friedrich Wöhler heated anhydrous yttrium(III) chloride with potassium to form metallic yttrium and potassium chloride.[6][7]

In 1869, Russian chemist Dmitri Mendeleev published his periodic table, which had empty spaces for elements directly above and under yttrium.[8] Mendeleev made several predictions on the upper neighbor of yttrium, which he called eka-boron. 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.[9][10] 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 and germanium this proved the correctness of the whole periodic table and periodic law. Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized 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.[12]

In 1751, the Swedish mineralogist Axel Fredrik Cronstedt discovered a heavy mineral from the mine at Bastnäs, later named cerite. Thirty years later, the fifteen-year-old Vilhelm Hisinger, from the family owning the mine, sent a sample of it to Carl Scheele, who did not find any new elements within. In 1803, after Hisinger had become an ironmaster, he returned to the mineral with Jöns Jacob Berzelius and isolated a new oxide which they named ceria after the dwarf planet Ceres, which had been discovered two years earlier.[13] Ceria was simultaneously independently isolated in Germany by Martin Heinrich Klaproth.[14] Between 1839 and 1843, ceria was shown to be a mixture of oxides by the Swedish surgeon and chemist Carl Gustaf Mosander, who lived in the same house as Berzelius: he separated out two other oxides which he named lanthana and didymia.[15] He partially decomposed a sample of cerium nitrate by roasting it in air and then treating the resulting oxide with dilute nitric acid.[16] Since lanthanum's properties differed only slightly from those of cerium, and occurred along with it in its salts, he named it from the Ancient Greek λανθάνειν [lanthanein] (lit. to lie hidden).[14] Relatively pure lanthanum metal was first isolated in 1923.[17]

Lutetium was independently discovered in 1907 by French scientist Georges Urbain,[18] Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James[19] as an impurity in the mineral ytterbia, which was thought by most chemists to consist entirely of ytterbium. Welsbach proposed the names cassiopeium 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. 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.[20][21] 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.[22] The separation of lutetium from ytterbium was first described by Urbain and the naming honor therefore went to him, but neoytterbium was eventually reverted to ytterbium and in 1949, the spelling of element 71 was changed to lutetium.[23][24] 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.[25]

André-Louis Debierne, a French chemist, announced the discovery of actinium in 1899. He separated it from pitchblende residues left by Marie and Pierre Curie after they had extracted radium. In 1899, Debierne described the substance as similar to titanium[26] and (in 1900) as similar to thorium.[27] Friedrich Oskar Giesel independently discovered actinium in 1902[28] as a substance being similar to lanthanum and called it "emanium" in 1904.[29] After a comparison of the substances half-lives determined by Debierne,[30] Hariett Brooks in 1904, and Otto Hahn and Otto Sackur in 1905, Debierne's chosen name for the new element was retained because it had seniority, despite the contradicting chemical properties he claimed for the element at different times.[31][32]

Ernest Orlando Lawrence
Lawrencium, the only synthetic element in the group, was named after American physicist Ernest Lawrence, the inventor of the cyclotron atom-smasher and founder of discovery place, then-called Lawrence Radiation Laboratory (now Lawrence Berkeley National Laboratory)

Lawrencium was first synthesized by 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. The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator (HILAC).[33] The nuclide 257103 was originally reported, but then this was reassigned to 258103. 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",[33] 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.[34] Two years earlier, the Dubna team reported 256103.[35] In 1992, the IUPAC Trans-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.[36]

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. According to the principle, unpenttrium should have an electronic configuration of [Og]8s25g186f147d1[note 3] 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. Therefore, it is hard to calculate which element should be the next group 3 element.[37] Calculations suggest that unpentpentium (Upp, element 155) could also be the next group 3 element.[38] If lanthanum and actinium are considered group 3 elements, then element 121, unbiunium (Ubu), should be the fifth group 3 element. The element is calculated have electronic configuration of [Og]8s28p1/21, which is not associated with transition metals, without having a partially filled d-subshell.[37] No experiments have been performed to create unpenttrium, unbiunium or any element that could be considered the next group 3 element; however, unbiunium is the element with the lowest atomic number that has not been tried to be created and thus has chances to be,[39] while unpenttrium, unpentpentium or any other element considered if preceded by lawrencium is very unlikely to be created due to drip instabilities that imply that the periodic table ends soon after the island of stability at unbihexium.[40]

Characteristics

Chemical

Electron configurations of the group 3 elements[note 4]
Z Element Electron configuration
21 scandium 2, 8, 9, 2
39 yttrium 2, 8, 18, 9, 2
57 lanthanum 2, 8, 18, 18, 9, 2
89 actinium 2, 8, 18, 32, 18, 9, 2

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 7p1/2 subshell due to relativistic effects.[41][42]

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). They are usually oxidized to the +3 oxidation state, even though scandium,[43] yttrium[44][45] and lanthanum[17] 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. Scandium(III) oxide, yttrium(III) oxide, lanthanum(III) oxide and lutetium(III) oxide are white high-temperature-melting solids. Yttrium(III) oxide and lutetium(III) oxide exhibit weak basic character, but scandium(III) oxide is amphoteric.[46] Lanthanum(III) oxide is strongly basic.

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. 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. Due to the lanthanide contraction, lutetium, the last in the lanthanide series, has a significantly smaller atomic radius and a higher nucleus charge,[47] thus making the extraction of the electrons from the atom to form metallic bonding more difficult, and thus making the metal harder. However, lutetium suits the previous elements better in several other properties, such as melting[48] and boiling points.[49] Very little is known about lawrencium, and none of its physical properties have been confirmed.[50][51]

Properties of the group 3 elements[note 5]
Name Scandium Yttrium Lanthanum Actinium
Melting point[48] 1814 K, 1541 °C 1799 K, 1526 °C 1193 K, 920 °C 1323 K, 1050 °C
Boiling point[49] 3109 K, 2836 °C 3609 K, 3336 °C 3737 K, 3464 °C 3471 K, 3198 °C
Density 2.99 g·cm−3[52] 4.47 g·cm−3[53] 6.162 g·cm−3 10 g·cm−3
Appearance silver metallic silver white gray silvery
Atomic radius[47] 162 pm 180 pm 187 pm 215 pm

Composition of group 3

It is disputed whether lanthanum and actinium should be included in group 3, rather than lutetium and lawrencium. Other d-block groups are composed of four transition metals,[note 6] and group 3 is sometimes considered to follow suit. Scandium and yttrium are always classified as group 3 elements, but it is controversial which elements should follow them in group 3, lanthanum and actinium or lutetium and lawrencium. Scerri has proposed a resolution to this debate on the basis of moving to a 32-column table and consideration of which option results in a continuous sequence of atomic number increase. He thereby finds that group 3 should consist of Sc, Y, Lu, Lr.[54] The current IUPAC definition of the term "lanthanoid" includes fifteen elements including both lanthanum and lutetium, and that of "transition element"[55] applies to lanthanum and actinium, as well as lutetium but not lawrencium, since it does not correctly follow the Aufbau principle. Normally, the 103rd electron would enter the d-subshell, but quantum mechanical research has found that the configuration is actually [Rn]7s25f147p1[note 7] due to relativistic effects.[41][42] IUPAC thus has not recommended a specific format for the in-line-f-block periodic table, leaving the dispute open.

  • Lanthanum and actinium are sometimes considered the remaining members of group 3.[56] 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, 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. It has however been argued that this is irrelevant because the principle of increasing basicity down the table is more fundamental, and because the behavior of the group 3 elements is more similar to their s-block neighbors than their d-block neighbors.
  • In other tables, lutetium and lawrencium are classified as the remaining members of group 3.[57] In these tables, lutetium and lawrencium end (or sometimes succeed) the lanthanide and actinide series, respectively. Since the f-shell is nominally full in the ground state electron configuration for both of these metals, they behave most 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. However, this resemblance in not unique to lutetium and lawrencium, but is common among all the late lanthanides and actinides.
  • Some tables, including the one published by IUPAC[58] refer to all lanthanides and actinides as being in group 3: 30 lanthanide and actinide elements together with scandium and yttrium. 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.
  • Exclusion of all elements is based on properties of earlier actinides, which show a much wider variety of chemistry (for instance, in range of oxidation states) within their series than the lanthanides, and comparisons to scandium and yttrium are even less useful.[59] However, these elements are destabilized,[60] and if they were stabilized to more closely match chemistry laws, they would be similar to lanthanides as well. Also, the later actinides from californium onwards behave more like the corresponding lanthanides, with only the valence +3 (and sometimes +2) shown.[59]
  • In 2015, IUPAC initiated a project to decide

... group 3 of the periodic table as consisting either of
the elements Sc, Y, Lu and Lr, or
the elements Sc, Y, La and Ac.

— IUPAC, [61]
The project is led by Eric Scerri. Apparently, group 3 comprising 32 elements (as older periodic tables show) is not considered.

The La and Ac variant remains the most common in the literature, despite some calls for a change to the Lu and Lr variant. In terms of chemical behaviour,[62] and trends going down group 3 for properties such as melting point, electronegativity and ionic radius,[63][64] scandium, yttrium, lanthanum and actinium are similar to their group 1–2 counterparts. In this variant, the number of f electrons in the most common (trivalent) ions of the f-block elements consistently matches their position in the f-block.[65] For example, the f-electron counts for the trivalent ions of the first three f-block elements are Ce 1, Pr 2 and Nd 3.[66]

Occurrence

Scandium, yttrium, lanthanum, and lutetium tend to occur together with the other lanthanides (except promethium) 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 — 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. The abundance of lanthanum is greater, being about 35 ppm. For comparison, the abundance of copper is 50 ppm, that of chromium is 160 ppm, and that of molybdenum is 1.5 ppm.[56]

Scandium is distributed sparsely and occurs in trace amounts in many minerals.[67] Rare minerals from Scandinavia[68] and Madagascar[69] 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.[68] 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.[70]

Monazit - Mosambik, O-Afrika
Monazite, the most important lutetium ore

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. The main mining areas are China, United States, Brazil, India, Sri Lanka and Australia. Pure lutetium metal 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. Lanthanum is much more common, being the second most abundant rare earth, and in addition to monazite can also be extracted economically from bastnäsite.[71][72]

Production

The most available element in group 3 is yttrium, with annual production of 8,900 tonnes in 2010. Yttrium is mostly produced as oxide, by a single country, China (99%).[73] Lutetium and scandium are also mostly obtained as oxides, and their annual production by 2001 was about 10 and 2 tonnes, respectively.[74]

Group 3 elements are mined only as a byproduct from the extraction of other elements.[75] 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;[75][76] 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.[77] The resulting fluorides are reduced with alkaline earth metals or alloys of the metals; metallic calcium is used most frequently.[77] 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. 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.[78] 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.[78] 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.[78]

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.[79] There is normally as little as 0.5 milligrams found within the entire human body; human breast milk contains 4 ppm.[80] Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount.[80] With up to 700 ppm, the seeds of woody plants have the highest known concentrations.[80]

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.[81] 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.[81] 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.[81] Lanthanum is not essential for humans and has a low to moderate level of toxicity. However, it is essential for the methanotrophic bacterium Methylacidiphilum fumariolicum SolV, although the general similarity of the rare earths means that it may be substituted by some of the other early lanthanides with no ill effects.[82]

The high radioactivity of lawrencium would make it highly toxic to living cells, causing radiation poisoning. The same is true for actinium.

Notes

The Scandium sub-group comprises Scandium (sc),yttrium (Y) Lanthanum (La) and Actinium (Ac). In addition, the element of the cerium and thorium families are also included in the sub-group. the main characteristics of scandium and its analogous are summarised below: Atomic No. ( Sc)21 ( Y)39 ( La )57 Atomic wt. (44.95) (88A^9) (138;9) Valency electron. (3d'4s2) Scandium and its analogous are the first d-elements of thair period i.e.they are the first whose d-subs-hell of the penultimate shell being to be filled the presency of just one electron in the d-state accounts for the stabiliry oxidation state of III in scandium and its analogous. the stable co-ordonationv number increases in the transition from scandium to yttrium and

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  1. ^ Ytterbite was named after the village it was discovered near, plus the -ite ending to indicate it was a mineral.
  2. ^ Earths were given an -a ending and new elements are normally given an -ium ending.
  3. ^ Unpenttrium, according to calculations, should have an electronic configuration of [Og]8s25g186f117d28p1/22.[37]
  4. ^ If lutetium and lawrencium are included instead, the table ends with the following lines:
    Electron configurations of the group 3 elements
    Z Element Electron configuration
    71 lutetium 2, 8, 18, 32, 9, 2
    103 lawrencium 2, 8, 18, 32, 32, 8, 3
  5. ^ If lutetium and lawrencium are included instead, the table ends with the following lines (the data for lawrencium is approximate):
    Properties of the group 3 elements
    Name Lutetium Lawrencium
    Melting point 1925 K, 1652 °C ? 1900 K, ? 1627 °C
    Boiling point 3675 K, 3402 °C ?
    Density 9.84 g·cm−3 ? 16 g·cm−3
    Appearance silver gray ?
    Atomic radius 174 pm ?
    Source: Lide, D. R., ed. (2003). CRC Handbook of Chemistry and Physics (84th ed.). Boca Raton, FL: CRC Press.
  6. ^ However, the group 12 elements are not always considered to be transition metals.
  7. ^ The expected configuration of lawrencium if it did obey the Aufbau principle would be [Rn]7s25f146d1, with the normal incomplete 6d-subshell in the neutral state.

Bibliography

3 (disambiguation)

3 is a number, numeral, and glyph.

3, three, or III may also refer to:

AD 3, the third year of the AD era

3 BC, the third year before the AD era

March, the third month

Actinide

The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.Strictly speaking, both actinium and lawrencium have been labeled as group 3 elements, but both elements are often included in any general discussion of the chemistry of the actinide elements. Actinium is the more often omitted of the two, because its placement as a group 3 element is somewhat more common in texts and for semantic reasons: since "actinide" means "like actinium", it has been argued that actinium cannot logically be an actinide, even though IUPAC acknowledges its inclusion based on common usage.The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, with the exception being either actinium or lawrencium. The series mostly corresponds to the filling of the 5f electron shell, although actinium and thorium lack any f-electrons, and curium and lawrencium have the same number as the preceding element. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. They all have very large atomic and ionic radii and exhibit an unusually large range of physical properties. While actinium and the late actinides (from americium onwards) behave similarly to the lanthanides, the elements thorium, protactinium, and uranium are much more similar to transition metals in their chemistry, with neptunium and plutonium occupying an intermediate position.

All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors.

Of the actinides, primordial thorium and uranium occur naturally in substantial quantities. The radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium and plutonium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium, einsteinium and fermium.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. 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).

Actinide chemistry

Actinide chemistry (or actinoid chemistry) is one of the main branches of nuclear chemistry that investigates the processes and molecular systems of the actinides. The actinides derive their name from the group 3 element actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. The actinide series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

Group 3

Group 3 may refer to:

Group 3 element, chemical element classification

Group 3 (racing), FIA classification for auto racing

Group 3, the third tier of races in worldwide Thoroughbred horse racing

Group 3 image format, Group 3 & Group 4 are digital technical standard for compressing and sending faxes

Group 3 Rugby League, a rugby competition in Australia

Group 3 Films, a British film production organisation funded by the National Film Finance Corporation

Index of chemistry articles

Chemistry (from Egyptian kēme (chem), meaning "earth") is the physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.Below is a list of chemistry-related articles. Chemical compounds are listed separately at list of organic compounds, list of inorganic compounds or list of biomolecules.

Lanthanide

The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.

The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell; depending on the source, either lanthanum or lutetium is considered a d-block element, but is included due to its chemical similarities with the other 14. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.

They are called lanthanides because the elements in the series are chemically similar to lanthanum. Both lanthanum and lutetium have been labeled as group 3 elements, because they have a single valence electron in the 5d shell. However, both elements are often included in discussions of the chemistry of lanthanide elements. Lanthanum is the more often omitted of the two, because its placement as a group 3 element is somewhat more common in texts and for semantic reasons: since "lanthanide" means "like lanthanum", it has been argued that lanthanum cannot logically be a lanthanide, but IUPAC acknowledges its inclusion based on common usage.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 and actinium, or lutetium and lawrencium) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. 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).

Lanthanum

Lanthanum is a chemical element with symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also sometimes considered the first element of the 6th-period transition metals, which would put it in group 3, although lutetium is sometimes placed in this position instead. Lanthanum is traditionally counted among the rare earth elements. The usual oxidation state is +3. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.

Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Ancient Greek λανθάνειν (lanthanein), meaning "to lie hidden". Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth's crust, almost three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum composes about a quarter of the lanthanide content. It is extracted from those minerals by a process of such complexity that pure lanthanum metal was not isolated until 1923.

Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon arc lamps for studio lights and projectors, ignition elements in lighters and torches, electron cathodes, scintillators, GTAW electrodes, and other things. Lanthanum carbonate is used as a phosphate binder in cases of renal failure. It is also an element in the 6th period and in the 3rd group.

Lawrencium

Lawrencium is a synthetic chemical element with symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and is also the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Twelve isotopes of lawrencium are currently known; the most stable is 266Lr with a half-life of 11 hours, but the shorter-lived 260Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale.

Chemistry experiments have confirmed that lawrencium behaves as a heavier homolog to lutetium in the periodic table, and is a trivalent element. It thus could also be classified as the first of the 7th-period transition metals: however, its electron configuration is anomalous for its position in the periodic table, having an s2p configuration instead of the s2d configuration of its homolog lutetium. This means that lawrencium may be more volatile than expected for its position in the periodic table and have a volatility comparable to that of lead.

In the 1950s, 1960s, and 1970s, many claims of the synthesis of lawrencium of varying quality were made from laboratories in the Soviet Union and the United States. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, and while the International Union of Pure and Applied Chemistry (IUPAC) initially established lawrencium as the official name for the element and gave the American team credit for the discovery, this was reevaluated in 1997, giving both teams shared credit for the discovery but not changing the element's name.

Period 7 element

A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered. As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells, in that order; however, there are exceptions, such as plutonium.

Rare-earth element

A rare-earth element (REE) or rare-earth metal (REM), as defined by IUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. Rarely, a broader definition that includes actinides may be used, since the actinides share some mineralogical, chemical, and physical (especially electron shell configuration) characteristics.The 17 rare-earth elements are cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).

Despite their name, rare-earth elements are – with the exception of the radioactive promethium – relatively plentiful in Earth's crust, with cerium being the 25th most abundant element at 68 parts per million, more abundant than copper. However, because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals; as a result economically exploitable ore deposits are less common. The first rare-earth mineral discovered (1787) was gadolinite, a mineral composed of cerium, yttrium, iron, silicon, and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare-earth elements bear names derived from this single location.

Unbiunium

Unbiunium, also known as eka-actinium or simply element 121, is the hypothetical chemical element with symbol Ubu and atomic number 121. Unbiunium and Ubu are the temporary systematic IUPAC name and symbol respectively, until a permanent name is decided upon. In the periodic table of the elements, it is expected to be the first of the superactinides, and the third element in the eighth period: analogously to lanthanum and actinium, it could be considered the fifth member of group 3 and the first member of the fifth-row transition metals. It has attracted attention because of some predictions that it may be in the island of stability, although newer calculations expect the island to actually occur at a slightly lower atomic number, closer to copernicium and flerovium.

Unbiunium has not yet been synthesized. Nevertheless, because it is only three elements away from the heaviest known element, oganesson (element 118), its synthesis may come in the near future; it is expected to be one of the last few reachable elements with current technology, and the limit may be anywhere between element 120 and 124. It will also likely be far more difficult to synthesize than the elements known so far up to 118, and still more difficult than elements 119 and 120. The team at RIKEN in Japan has plans to attempt the synthesis of element 121 in the future after its attempts on elements 119 and 120.

The position of unbiunium in the periodic table suggests that it would have similar properties to its lighter congeners, scandium, yttrium, lanthanum, and actinium; however, relativistic effects may cause some of its properties to differ from those expected from a straight application of periodic trends. For example, unbiunium is expected to have a s2p valence electron configuration instead of the s2d of its lighter congeners in group 3, but this is not expected to significantly affect its chemistry, which is predicted to be that of a normal group 3 element; it would on the other hand significantly lower its first ionisation energy beyond what would be expected from periodic trends.

Periodic table forms
Sets of elements
Elements
History
See also
Group 3 elements

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