The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The first two members of the group share similar properties as they are solid metals under standard conditions. Mercury is the onlymetal that is known to be a liquid at room temperature – as copernicium's boiling point has not yet been measured accurately enough,[note 2] it is not yet known whether it is a liquid or a gas under standard conditions. While zinc is very important in the biochemistry of living organisms, cadmium and mercury are both highly toxic. As copernicium does not occur in nature, it has to be synthesized in the laboratory.
Like othergroups of theperiodic table, the members of group 12 show patterns in its electron configuration, especially the outermost shells, which result in trends in their chemical behavior:
The group 12 elements are all soft,diamagnetic,divalent metals. They have the lowest melting points among alltransition metals.[8] Zinc is bluish-white and lustrous,[9] though most common commercial grades of the metal have a dull finish.[10] Zinc is also referred to in nonscientific contexts asspelter.[11] Cadmium is soft,malleable,ductile, and with a bluish-white color. Mercury is a liquid, heavy, silvery-white metal. It is the only common liquid metal at ordinary temperatures, and as compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.[12]
The table below is a summary of the key physical properties of the group 12 elements. The data forcopernicium is based on relativistic density-functional theory simulations.[13]
Zinc is somewhat less dense thaniron and has a hexagonalcrystal structure.[14] The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C (212 and 302 °F).[9][10] Above 210 °C (410 °F), the metal becomes brittle again and can be pulverized by beating.[15] Zinc is a fairconductor of electricity.[9] For a metal, zinc has relatively low melting (419.5 °C, 787.1 °F) and boiling points (907 °C, 1,665 °F).[8] Cadmium is similar in many respects to zinc but formscomplex compounds.[16] Unlike other metals, cadmium is resistant tocorrosion and as a result it is used as a protective layer when deposited on other metals. As a bulk metal, cadmium is insoluble in water and is notflammable; however, in its powdered form it may burn and release toxic fumes.[17] Mercury has an exceptionally low melting temperature for a d-block metal. A complete explanation of this fact requires a deep excursion intoquantum physics, but it can be summarized as follows: mercury has a unique electronic configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d and 6s subshells. As such configuration strongly resists removal of an electron, mercury behaves similarly tonoble gas elements, which form weak bonds and thus easily melting solids. The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the nuclear charge that increases the attractiveCoulomb interaction of the 6s shell and the nucleus (seelanthanide contraction). The absence of a filled inner f shell is the reason for the somewhat higher melting temperature of cadmium and zinc, although both these metals still melt easily and, in addition, have unusually low boiling points.Gold has atoms with one less 6s electron than mercury. Those electrons are more easily removed and are shared between the gold atoms forming relatively strongmetallic bonds.[18][19]
Zinc, cadmium and mercury form a large range ofalloys. Among the zinc containing ones,brass is an alloy of zinc andcopper. Other metals long known to form binary alloys with zinc arealuminium,antimony,bismuth,gold, iron,lead, mercury,silver,tin,magnesium,cobalt,nickel,tellurium andsodium.[11] While neither zinc norzirconium areferromagnetic, their alloyZrZn 2 exhibits ferromagnetism below 35 K.[9] Cadmium is used in many kinds ofsolder and bearing alloys, due to a lowcoefficient of friction and fatigue resistance.[20] It is also found in some of the lowest-melting alloys, such asWood's metal.[21] Because it is a liquid, mercury dissolves other metals and the alloys that are formed are calledamalgams. For example, such amalgams are known with gold, zinc, sodium, and many other metals. Because iron is an exception, iron flasks have been traditionally used to trade mercury. Other metals that do not form amalgams with mercury includetantalum,tungsten andplatinum.Sodium amalgam is a common reducing agent inorganic synthesis, and is also used inhigh-pressure sodium lamps. Mercury readily combines withaluminium to form amercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam reacts with air to give aluminium oxide, small amounts of mercury corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.[22]
Most of the chemistry has been observed only for the first three members of the group 12. The chemistry of copernicium is not well established and therefore the rest of the section deals only with zinc, cadmium and mercury.
All elements in this group aremetals. The similarity of the metallic radii of cadmium and mercury is an effect of thelanthanide contraction. So, the trend in this group is unlike the trend in group 2, thealkaline earths, where metallic radius increases smoothly from top to bottom of the group. All three metals have relatively low melting and boiling points, indicating that themetallic bond is relatively weak, with relatively little overlap between thevalence band and theconduction band.[23] Thus, zinc is close to the boundary between metallic andmetalloid elements, which is usually placed betweengallium andgermanium, though gallium participates insemi-conductors such asgallium arsenide.
Zinc and cadmium areelectropositive while mercury is not.[23] As a result, zinc and cadmium metal are good reducing agents. The elements of group 12 have an oxidation state of +2 in which the ions have the rather stable d10 electronic configuration, with a fullsub-shell. However, mercury can easily be reduced to the +1 oxidation state; usually, as in the ionHg2+ 2, two mercury(I) ions come together to form a metal-metal bond and adiamagnetic species.[24] Cadmium can also form species such as [Cd2Cl6]4− in which the metal's oxidation state is +1. Just as with mercury, the formation of a metal-metal bond results in a diamagnetic compound in which there are no unpaired electrons; thus, making the species very reactive. Zinc(I) is known mostly in the gas phase, in such compounds as linear Zn2Cl2, analogous tocalomel. In the solid phase, the rather exotic compounddecamethyldizincocene (Cp*Zn–ZnCp*) is known.
The elements in group 12 are usually considered to bed-block elements, but nottransition elements as the d-shell is full. Some authors classify these elements asmain-group elements because thevalence electrons are in ns2 orbitals. Nevertheless, they share many characteristics with the neighboringgroup 11 elements on the periodic table, which are almost universally considered to be transition elements. For example, zinc shares many characteristics with the neighboring transition metal, copper. Zinc complexes merit inclusion in theIrving-Williams series as zinc forms many complexes with the samestoichiometry as complexes of copper(II), albeit with smallerstability constants.[25] There is little similarity between cadmium and silver as compounds of silver(II) are rare and those that do exist are very strong oxidizing agents. Likewise the common oxidation state for gold is +3, which precludes there being much common chemistry between mercury and gold, though there are similarities between mercury(I) and gold(I) such as the formation of linear dicyano complexes, [M(CN)2]−. According toIUPAC's definition of transition metal asan element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell,[26] zinc and cadmium are not transition metals, while mercury is. This is because only mercury is known to have a compound where its oxidation state is higher than +2, inmercury(IV) fluoride (though its existence is disputed, as later experiments trying to confirm its synthesis could not find evidence of HgF4).[27][28] However, this classification is based on one highly atypical compound seen at non-equilibrium conditions and is at odds to mercury's more typical chemistry, and Jensen has suggested that it would be better to regard mercury as not being a transition metal.[29]
Although group 12 lies in thed-block of the modern 18-column periodic table, the d electrons of zinc, cadmium, and (almost always) mercury behave as core electrons and do not take part in bonding. This behavior is similar to that of themain-group elements, but is in stark contrast to that of the neighboringgroup 11 elements (copper,silver, andgold), which also have filled d-subshells in their ground-stateelectron configuration but behave chemically as transition metals. For example, the bonding inchromium(II) sulfide (CrS) involves mainly the 3d electrons; that iniron(II) sulfide (FeS) involves both the 3d and 4s electrons; but that ofzinc sulfide (ZnS) involves only the 4s electrons and the 3d electrons behave as core electrons. Indeed, useful comparison can be made between their properties and the first two members ofgroup 2,beryllium andmagnesium, and in earlier short-form periodic table layouts, this relationship is illustrated more clearly. For instance, zinc and cadmium are similar to beryllium and magnesium in theiratomic radii,ionic radii,electronegativities, and also in the structure of theirbinary compounds and their ability to form complex ions with manynitrogen andoxygenligands, such as complexhydrides andamines. However, beryllium and magnesium are small atoms, unlike the heavieralkaline earth metals and like the group 12 elements (which have a greater nuclear charge but the same number ofvalence electrons), and theperiodic trends down group 2 from beryllium toradium (similar to that of thealkali metals) are not as smooth when going down from beryllium to mercury (which is more similar to that of the p-block main groups) due to thed-block andlanthanide contractions. It is also the d-block and lanthanide contractions that give mercury many of its distinctive properties.[29]
Comparison of the properties of the alkaline earth metals and the group 12 elements (predictions for copernicium)[29]
All three metal ions form manytetrahedral species, such asMCl2− 4. Both zinc and cadmium can also form octahedral complexes such as theaqua ions [M(H2O)6]2+ which are present in aqueous solutions of salts of these metals.[35] Covalent character is achieved by using the s and p orbitals. Mercury, however, rarely exceeds acoordination number of four. Coordination numbers of 2, 3, 5, 7 and 8 are also known.
The elements of group 12 have been found throughout history, being used since ancient times to being discovered in laboratories. The group itself has not acquired atrivial name, but it has been calledgroup IIB in the past.
Zinc has been found being used in impure forms in ancient times as well as in alloys such as brass that have been found to be over 2000 years old.[36][37] Zinc was distinctly recognized as a metal under the designation ofFasada in the medical Lexicon ascribed to the Hindu king Madanapala (of Taka dynasty) and written about the year 1374.[38] The metal was also of use toalchemists.[39] The name of the metal was first documented in the 16th century,[40][41] and is probably derived from the Germanzinke for the needle-like appearance of metallic crystals.[42]
Alchemical symbol for the element zinc
The isolation of metallic zinc in the West may have been achieved independently by several people in the 17th century.[43] German chemistAndreas Marggraf is usually given credit for discovering pure metallic zinc in a 1746 experiment by heating a mixture ofcalamine and charcoal in a closed vessel without copper to obtain a metal.[44] Experiments on frogs by the Italian doctorLuigi Galvani in 1780 with brass paved the way for the discovery ofelectrical batteries, galvanization andcathodic protection.[45][46] In 1799, Galvani's friend,Alessandro Volta, invented theVoltaic pile.[45] The biological importance of zinc was not discovered until 1940 whencarbonic anhydrase, an enzyme that scrubs carbon dioxide from blood, was shown to have zinc in itsactive site.[47]
The symbol forthe planet Mercury (☿) has been used since ancient times to represent the element.
Mercury has been found in Egyptian tombs which have been dated back to 1500 BC,[56] where mercury was used in cosmetics. It was also used by the ancient Chinese who believed it would improve and prolong health.[57] By 500 BC mercury was used to makeamalgams (Medieval Latin amalgama, "alloy of mercury") with other metals.[58]Alchemists thought of mercury as theFirst Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity ofsulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at thetransmutation of base (or impure) metals into gold, which was the goal of many alchemists.[59]
Hg is the modernchemical symbol for mercury. It comes fromhydrargyrum, aLatinized form of theGreek word Ύδραργυρος (hydrargyros), which is a compound word meaning "water-silver" (hydr- = water, argyros = silver) — since it is liquid like water and shiny like silver. The element was named after the Roman godMercury, known for speed and mobility. It is associated with the planetMercury; the astrological symbol for the planet is also one of thealchemical symbols for the metal.[60] Mercury is the only metal for which the alchemical planetary name became the common name.[59]
Like in most otherd-block groups, theabundance in Earth's crust of group 12 elements decreases with higher atomic number. Zinc is with 65parts per million (ppm) the most abundant in the group while cadmium with 0.1 ppm and mercury with 0.08 ppm are orders of magnitude less abundant.[63] Copernicium, as a synthetic element with ahalf-life of a few minutes, may only be present in the laboratories where it was produced.
Group 12 metals arechalcophiles, meaning the elements have low affinities foroxides and prefer to bond withsulfides. Chalcophiles formed as the crust solidified under thereducing conditions of the early Earth's atmosphere.[64] The commercially most important minerals of group 12 elements are sulfide minerals.[23]Sphalerite, which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains 60–62% zinc.[14] No significant deposits of cadmium-containing ores are known.Greenockite (CdS), the only cadmiummineral of importance, is nearly always associated with sphalerite (ZnS). This association is caused by the geochemical similarity between zinc and cadmium which makes geological separation unlikely. As a consequence, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfidic ores of zinc, and, to a lesser degree,lead andcopper.[65][66] One place where metallic cadmium can be found is theVilyuy River basin inSiberia.[67] Although mercury is an extremely rare element in the Earth'scrust,[68] because it does not blendgeochemically with those elements that constitute the majority of the crustal mass, mercury ores can be highly concentrated considering the element's abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or incinnabar (HgS),corderoite,livingstonite and otherminerals, with cinnabar being the most common ore.[69]
While mercury and zinc minerals are found in large enough quantities to be mined, cadmium is too similar to zinc and therefore is always present in small quantities in zinc ores from where it is recovered. Identified world zinc resources total about 1.9 billiontonnes.[70] Large deposits are in Australia, Canada and the United States with the largest reserves inIran.[64][71][72] At the current rate of consumption, these reserves are estimated to be depleted sometime between 2027 and 2055.[73][74] About 346 million tonnes have been extracted throughout history to 2002, and one estimate found that about 109 million tonnes of that remains in use.[75] In 2005, China was the top producer of mercury with almost two-thirds global share followed byKyrgyzstan.[76] Several other countries are believed to have unrecorded production of mercury from copperelectrowinning processes and by recovery from effluents. Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning.[77]
Zinc is the fourth most common metal in use, trailing onlyiron,aluminium, andcopper with an annual production of about 10 million tonnes.[78] Worldwide, 95% of the zinc is mined fromsulfidic ore deposits, in which sphalerite (ZnS) is nearly always mixed with the sulfides of copper, lead and iron. Zinc metal is produced usingextractive metallurgy.[79]Roasting converts the zinc sulfide concentrate produced during processing to zinc oxide.[80] For further processing two basic methods are used:pyrometallurgy orelectrowinning. Pyrometallurgy processing reduces zinc oxide withcarbon orcarbon monoxide at 950 °C (1,740 °F) into the metal, which is distilled as zinc vapor.[81] The zinc vapor is collected in a condenser.[80] Electrowinning processing leaches zinc from the ore concentrate bysulfuric acid.[82] After this stepelectrolysis is used to produce zinc metal.[80]
Cadmium is a common impurity in zinc ores, and it is most isolated during the production of zinc. Some zinc ores concentrates from sulfidic zinc ores contain up to 1.4% of cadmium.[83] Cadmium is isolated from the zinc produced from the flue dust byvacuum distillation if the zinc is smelted, or cadmium sulfate isprecipitated out of the electrolysis solution.[84]
The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury, with cinnabar (HgS) being the most common ore in the deposits.[85]Mercury is extracted by heating cinnabar in a current of air and condensing the vapor.[86]
Superheavy elements such as copernicium are produced by bombarding lighter elements inparticle accelerators that inducesfusion reactions. Whereas most of the isotopes of copernicium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higheratomic numbers.[87] The first fusion reaction to produce copernicium was performed by GSI in 1996, who reported the detection of two decay chains of copernicium-277 (though one was later retracted, as it had been based on data fabricated byVictor Ninov):[61]
Due to the physical similarities which they share, the group 12 elements can be found in many common situations. Zinc and cadmium are commonly used asanti-corrosion (galvanization) agents[2] as they will attract all localoxidation until they completely corrode.[88] These protective coatings can be applied to other metals byhot-dip galvanizing a substance into the molten form of the metal,[89] or through the process ofelectroplating which may bepassivated by the use ofchromate salts.[90] Group 12 elements are also used inelectrochemistry as they may act as an alternative to thestandard hydrogen electrode in addition to being a secondary reference electrode.[91]
In the US, zinc is used predominantly forgalvanizing (55%) and forbrass,bronze and other alloys (37%).[92] The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficientsacrificial anode incathodic protection (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe.[93] Zinc acts as theanode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline.[93][note 6] Zinc is used to cathodically protect metals that are exposed to sea water from corrosion.[94][95]Zinc is used as an anode material for batteries such as inzinc–carbon batteries[96][97] orzinc–air battery/fuel cells.[98][99][100]A widely used alloy which contains zinc is brass, in which copper is alloyed with anywhere from 3% to 45% zinc, depending upon the type of brass.[93] Brass is generally moreductile and stronger than copper and has superiorcorrosion resistance.[93] These properties make it useful in communication equipment, hardware, musical instruments, and water valves.[93] Other widely used alloys that contain zinc includenickel silver, typewriter metal, soft and aluminiumsolder, and commercialbronze.[9] Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful indie casting as well asspin casting, especially in the automotive, electrical, and hardware industries.[9] These alloys are marketed under the nameZamak.[101] Roughly one quarter of all zinc output in the United States (2009) is consumed in the form of zinc compounds, a variety of which are used industrially.[92]
Cadmium has many common industrial uses as it is a key component in battery production, is present incadmium pigments,[102] coatings,[90] and is commonly used in electroplating.[20] In 2009, 86% of cadmium was used inbatteries, predominantly inrechargeablenickel-cadmium batteries. The European Union banned the use of cadmium in electronics in 2004 with several exceptions but reduced the allowed content of cadmium in electronics to 0.002%.[103] Cadmiumelectroplating, consuming 6% of the global production, can be found in the aircraft industry due to the ability to resistcorrosion when applied to steel components.[20]
Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some thermometers, especially ones which are used to measure high temperatures. A still increasing amount is used as gaseous mercury influorescent lamps,[104] while most of the other applications are slowly phased out due to health and safety regulations,[105] and is in some applications replaced with less toxic but considerably more expensiveGalinstan alloy.[106] Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood.[107] It is still used as an ingredient indental amalgams. In the late 20th century the largest use of mercury[108][109] was in the mercury cell process (also called theCastner-Kellner process) in the production ofchlorine andcaustic soda.[110]
Copernicium has no use other than research due to its very high radioactivity.
The group 12 elements have multiple effects on biological organisms as cadmium and mercury are toxic while zinc is required by most plants and animals in trace amounts.
Zinc is an essentialtrace element, necessary for plants,[111] animals,[112] andmicroorganisms.[113] It is "typically the second most abundant transition metal in organisms" afteriron and it is the only metal which appears in allenzyme classes.[111] There are 2–4 grams of zinc[114] distributed throughout the human body,[115] and it plays "ubiquitous biological roles".[116] A 2006 study estimated that about 10% of human proteins (2800) potentially bind zinc, in addition to hundreds which transport and traffic zinc.[111] In the U.S., theRecommended Dietary Allowance (RDA) is 8 mg/day for women and 11 mg/day for men.[117] Harmful excessive supplementation may be a problem and should probably not exceed 20 mg/day in healthy people,[118] although the U.S. National Research Council set a Tolerable Upper Intake of 40 mg/day.[119]
Mercury and cadmium are toxic and may cause environmental damage if they enter rivers or rain water. This may result in contaminated crops[120] as well as thebioaccumulation of mercury in a food chain leading to an increase in illnesses caused bymercury andcadmium poisoning.[121]
^The color of the flame test of pure radium has never been observed; the crimson red color is an extrapolation from the flame test color of its compounds.[31]
^Housecroft, C. E.; Sharpe, A. G. (2008).Inorganic Chemistry (3rd ed.). Prentice Hall.ISBN978-0-13-175553-6.
^Eichler, R.; Aksenov, N. V.; Belozerov, A. V.; Bozhikov, G. A.; Chepigin, V. I.; Dmitriev, S. N.; Dressler, R.; Gäggeler, H. W.; Gorshkov, V. A.; Haenssler, F.; et al. (2007). "Chemical Characterization of Element 112".Nature.447 (7140):72–75.Bibcode:2007Natur.447...72E.doi:10.1038/nature05761.PMID17476264.S2CID4347419.
^Hammond, C. RThe Elements inLide, D. R., ed. (2005).CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press.ISBN0-8493-0486-5.
^Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Cadmium".Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. pp. 1056–1057.ISBN978-3-11-007511-3.
^Norrby, L.J. (1991). "Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks?".Journal of Chemical Education.68 (2): 110.Bibcode:1991JChEd..68..110N.doi:10.1021/ed068p110.
^Lindberg, S. E.; Stratton, W. J. (1998). "Atmospheric Mercury Speciation: Concentrations and Behavior of Reactive Gaseous Mercury in Ambient Air".Environmental Science and Technology.32 (1):49–57.Bibcode:1998EnST...32...49L.doi:10.1021/es970546u.
^Al-Niaimi, N. S.; Hamid, H. A. (1976). "Stabilities of nickel(II), copper(II), zinc(II) and dioxouranium(II) complexes of some β-diketones".Journal of Inorganic and Nuclear Chemistry.3 (5):849–852.doi:10.1016/0022-1902(77)80167-X.
^Wang, Xuefang; Andrews, Lester; Riedel, Sebastian; Kaupp, Martin (2007). "Mercury is a Transition Metal: The First Experimental Evidence for HgF4".Angewandte Chemie.119 (44):8523–8527.Bibcode:2007AngCh.119.8523W.doi:10.1002/ange.200703710.
^abcHaire, Richard G. (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.).The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands:Springer Science+Business Media. p. 1675.ISBN978-1-4020-3555-5.
^Bodsworth, Colin (1994).The Extraction and Refining of Metals. CRC Press. p. 148.ISBN978-0-8493-4433-6.
^Gupta, C. K.; Mukherjee, T. K. (1990).Hydrometallurgy in Extraction Processes. CRC Press. p. 62.ISBN978-0-8493-6804-2.
^National Research Council, Panel on Cadmium, Committee on Technical Aspects of Critical and Strategic Material (1969).Trends in Usage of Cadmium: Report. National Research Council, National Academy of Sciences-National Academy of Engineering. pp. 1–3.
^Bounoughaz, M.; Salhi, E.; Benzine, K.; Ghali, E.; Dalard, F. (2003). "A comparative study of the electrochemical behaviour of Algerian zinc and a zinc from a commercial sacrificial anode".Journal of Materials Science.38 (6):1139–1145.Bibcode:2003JMatS..38.1139B.doi:10.1023/A:1022824813564.S2CID135744939.
^Cooper, J. F.; Fleming, D.; Hargrove, D.; Koopman; R.; Peterman, K. (1995). "A refuelable zinc/air battery for fleet electric vehicle propulsion".NASA Sti/Recon Technical Report N.96. Society of Automotive Engineers future transportation technology conference and exposition: 11394.Bibcode:1995STIN...9611394C.OSTI82465.
^"Mercury Reduction Act of 2003". United States. Congress. Senate. Committee on Environment and Public Works. Retrieved2009-06-06.
^Surmann, P.; Zeyat, H. (Nov 2005). "Voltammetric analysis using a self-renewable non-mercury electrode".Analytical and Bioanalytical Chemistry.383 (6):1009–13.doi:10.1007/s00216-005-0069-7.PMID16228199.S2CID22732411.
^Zinc's role in microorganisms is particularly reviewed in:Sugarman, B. (1983). "Zinc and infection".Reviews of Infectious Diseases.5 (1):137–47.doi:10.1093/clinids/5.1.137.PMID6338570.
Weeks, Mary Elvira (1933). "III. Some Eighteenth-Century Metals".The Discovery of the Elements. Easton, PA: Journal of Chemical Education.ISBN978-0-7661-3872-8.{{cite book}}:ISBN / Date incompatibility (help)
.svg)
