Difference between revisions of "Zinc" - New World Encyclopedia
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| − | {{Elementbox_header | number=30 | symbol=Zn | name=zinc | left=[[copper]] | right=[[gallium]] | above=- | below=[[cadmium|Cd]] | color1= | + | {{Images OK}} |
| + | {{Elementbox_header | number=30 | symbol=Zn | name=zinc | left=[[copper]] | right=[[gallium]] | above=- | below=[[cadmium|Cd]] | color1={{Element color/Transition metals}} | color2=black }} | ||
{{Elementbox_series | [[transition metal]]s }} | {{Elementbox_series | [[transition metal]]s }} | ||
{{Elementbox_groupperiodblock | group=12 | period=4 | block=d }} | {{Elementbox_groupperiodblock | group=12 | period=4 | block=d }} | ||
{{Elementbox_appearance_img | Zn,30| bluish pale gray }} | {{Elementbox_appearance_img | Zn,30| bluish pale gray }} | ||
| − | {{Elementbox_atomicmass_gpm | [[1 E-25 kg|65.409(4)]] }} | + | {{Elementbox_atomicmass_gpm | [[1 E-25 kg|65.409]][[List of elements by atomic mass|(4)]] }} |
{{Elementbox_econfig | [[[argon|Ar]]] 3d<sup>10</sup> 4s<sup>2</sup> }} | {{Elementbox_econfig | [[[argon|Ar]]] 3d<sup>10</sup> 4s<sup>2</sup> }} | ||
{{Elementbox_epershell | 2, 8, 18, 2 }} | {{Elementbox_epershell | 2, 8, 18, 2 }} | ||
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{{Elementbox_heatcapacity_jpmolkat25 | 25.390 }} | {{Elementbox_heatcapacity_jpmolkat25 | 25.390 }} | ||
{{Elementbox_vaporpressure_katpa | 610 | 670 | 750 | 852 | 990 | (1185) | comment= }} | {{Elementbox_vaporpressure_katpa | 610 | 670 | 750 | 852 | 990 | (1185) | comment= }} | ||
| − | {{Elementbox_section_atomicprop | color1= | + | {{Elementbox_section_atomicprop | color1={{Element color/Transition metals}} | color2=black }} |
| − | {{Elementbox_crystalstruct | hexagonal }} | + | {{Elementbox_crystalstruct |
| + | | hexagonal }} | ||
{{Elementbox_oxistates | 2<br />([[Amphoteric (chemistry)|amphoteric]] oxide) }} | {{Elementbox_oxistates | 2<br />([[Amphoteric (chemistry)|amphoteric]] oxide) }} | ||
{{Elementbox_electroneg_pauling | 1.65 }} | {{Elementbox_electroneg_pauling | 1.65 }} | ||
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{{Elementbox_covalentradius_pm | [[1 E-10 m|131]] }} | {{Elementbox_covalentradius_pm | [[1 E-10 m|131]] }} | ||
{{Elementbox_vanderwaalsrad_pm | [[1 E-10 m|139]] }} | {{Elementbox_vanderwaalsrad_pm | [[1 E-10 m|139]] }} | ||
| − | {{Elementbox_section_miscellaneous | color1= | + | {{Elementbox_section_miscellaneous | color1={{Element color/Transition metals}} | color2=black }} |
{{Elementbox_magnetic | [[diamagnetism|diamagnetic]] }} | {{Elementbox_magnetic | [[diamagnetism|diamagnetic]] }} | ||
{{Elementbox_eresist_ohmmat20 | 59.0 n}} | {{Elementbox_eresist_ohmmat20 | 59.0 n}} | ||
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{{Elementbox_brinellhardness_mpa | 412 }} | {{Elementbox_brinellhardness_mpa | 412 }} | ||
{{Elementbox_cas_number | 7440-66-6 }} | {{Elementbox_cas_number | 7440-66-6 }} | ||
| − | {{Elementbox_isotopes_begin | isotopesof=zinc | color1= | + | {{Elementbox_isotopes_begin | isotopesof=zinc | color1={{Element color/Transition metals}} | color2=black }} |
{{Elementbox_isotopes_stable | mn=64 | sym=Zn | na=48.6% | n=34 }} | {{Elementbox_isotopes_stable | mn=64 | sym=Zn | na=48.6% | n=34 }} | ||
{{Elementbox_isotopes_decay2 | mn=65 | sym=Zn | na=[[synthetic radioisotope|syn]] | hl=[[1 E7 s|244.26]] [[day|d]] | dm1=[[electron capture|ε]] | de1=- | pn1=65 | ps1=[[copper|Cu]] | dm2=[[gamma radiation|γ]] | de2=1.1155 | pn2= | ps2=- }} | {{Elementbox_isotopes_decay2 | mn=65 | sym=Zn | na=[[synthetic radioisotope|syn]] | hl=[[1 E7 s|244.26]] [[day|d]] | dm1=[[electron capture|ε]] | de1=- | pn1=65 | ps1=[[copper|Cu]] | dm2=[[gamma radiation|γ]] | de2=1.1155 | pn2= | ps2=- }} | ||
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{{Elementbox_isotopes_stable | mn=67 | sym=Zn | na=4.1% | n=37 }} | {{Elementbox_isotopes_stable | mn=67 | sym=Zn | na=4.1% | n=37 }} | ||
{{Elementbox_isotopes_stable | mn=68 | sym=Zn | na=18.8% | n=38 }} | {{Elementbox_isotopes_stable | mn=68 | sym=Zn | na=18.8% | n=38 }} | ||
| − | {{Elementbox_isotopes_decay | mn=69 | sym=Zn | na=[[synthetic radioisotope|syn]] | hl=56.4 min | dm=[[Beta decay|β<sup> | + | {{Elementbox_isotopes_decay | mn=69 | sym=Zn | na=[[synthetic radioisotope|syn]] | hl=56.4 min | dm=[[Beta decay|β<sup>−</sup>]] | de=0.906 | pn=69 | ps=[[gallium|Ga]] }} |
{{Elementbox_isotopes_stable | mn=70 | sym=Zn | na=0.6% | n=40 }} | {{Elementbox_isotopes_stable | mn=70 | sym=Zn | na=0.6% | n=40 }} | ||
{{Elementbox_isotopes_end}} | {{Elementbox_isotopes_end}} | ||
| − | {{Elementbox_footer | color1= | + | {{Elementbox_footer | color1={{Element color/Transition metals}} | color2=black }} |
| − | '''Zinc''' (from German '' | + | '''Zinc''' (from German ''zink'') is a [[chemical element]] in the [[periodic table]] that has the symbol '''Zn''' and [[atomic number]] 30. |
== Notable characteristics == | == Notable characteristics == | ||
| − | Zinc is a moderately reactive [[metal]] that | + | Zinc is a moderately reactive bluish-white [[metal]] that tarnishes in moist air producing a layer of [[carbonate]]. It reacts with acids and alkalis and other non-metals. If not completely pure, zinc reacts with dilute [[acid]]s to release [[hydrogen]]. The one common [[oxidation state]] of zinc is +2. |
== Applications == | == Applications == | ||
Zinc is the fourth most common metal in use, trailing only [[iron]], [[aluminium]], and [[copper]] in annual production. | Zinc is the fourth most common metal in use, trailing only [[iron]], [[aluminium]], and [[copper]] in annual production. | ||
| − | * Zinc is used to [[galvanization|galvanize]] | + | * Zinc is used to [[galvanization|galvanize]] [[steel]] to prevent corrosion. |
| − | * Zinc is used in alloys such as [[brass]], | + | * Zinc is used to [[Parkerize]] steel to prevent rust and corrosion |
| − | * Zinc is the primary metal used in making American [[Penny (U.S. coin)| | + | * Zinc is used in alloys such as [[brass]], nickelled silver, typewriter metal, various [[solder]]ing formulas and [[German silver]]. |
| − | * Zinc is used in die [[casting]] | + | * Zinc is the primary metal used in making American [[Penny (U.S. coin)|cents]] since 1982. |
| + | * Zinc is used in die [[casting]] notably in the [[automobile industry]]. | ||
* Zinc is used as part of the containers of [[battery (electricity)|batteries]]. | * Zinc is used as part of the containers of [[battery (electricity)|batteries]]. | ||
| − | * [[Zinc oxide]] is used as a white pigment in | + | * Zinc is used in contemporary [[pipe organ]] building as a substitute for the classic lead/tin alloy in pipes sounding the lowest (pedal) tones, as it is tonally almost indistinguishable from lead/tin at those pitches, and has the added advantages of being much more economical and lighter in weight. Even the best organ builders will use zinc in this capacity. |
| − | * [[Zinc chloride]] is used as a deodorant and can be used as a wood [[preservative]]. | + | * [[Zinc oxide]] is used as a white pigment in watercolours or [[paint]]s, and as an activator in the [[rubber]] industry. As an over-the-counter ointment, it is applied as a thin coating on the exposed skin of the face or nose to prevent dehydration of the area of skin. It can protect against [[sunburn]] in the summer and windburn in the winter. Applied thinly to a baby's diaper area (perineum) with each diaper change, it can protect against [[rash]]. As determined in the [[Age-Related Eye Disease Study]], it's part of an effective treatment for [[age-related macular degeneration]] in some cases. |
| + | * Zinc is the fourth common material used in metal wall tiles, and is used for its germicidal properties in kitchens[http://www.metalwalltiles.net/zincTiles.htm]. | ||
| + | * [[Zinc chloride]] is used as a deodorant and can also be used as a wood [[preservative]]. | ||
* [[Zinc sulfide]] is used in [[luminescence|luminescent]] pigments such as on the hands of clocks and other items that glow in the dark. | * [[Zinc sulfide]] is used in [[luminescence|luminescent]] pigments such as on the hands of clocks and other items that glow in the dark. | ||
* [[Zinc methyl]] (Zn(CH<sub>3</sub>)<sub>2</sub>) is used in a number of organic [[chemical synthesis|syntheses]]. | * [[Zinc methyl]] (Zn(CH<sub>3</sub>)<sub>2</sub>) is used in a number of organic [[chemical synthesis|syntheses]]. | ||
* Zinc stearate is a lubricative plastic additive. | * Zinc stearate is a lubricative plastic additive. | ||
* Lotions made of [[calamine]], a mix of Zn-(hydroxy-)carbonates and silicates, are used to treat skin rash. | * Lotions made of [[calamine]], a mix of Zn-(hydroxy-)carbonates and silicates, are used to treat skin rash. | ||
| − | * Zinc metal is included in most single tablet over-the-counter daily vitamin and mineral | + | * Zinc metal is included in most single tablet over-the-counter daily vitamin and mineral supplements. It is believed to possess anti-oxidant properties, which protect against premature aging of the skin and muscles of the body. In larger amounts, taken as zinc alone in other proprietaries, it is believed by some to speed up the healing process after an injury. Preparations include [[zinc acetate]] and [[zinc gluconate]]. |
| − | * [[Zinc gluconate glycine]] | + | * [[Zinc gluconate glycine]] and [[zinc acetate]] are also used in [[throat lozenge]]s in an attempt to remedy the common cold.[http://www.annals.org/cgi/reprint/133/4/245.pdf] |
| + | * Zinc is used as the anode or fuel of the [[Zinc-air battery]]/Fuel Cell providing the basis of the [[Zinc Economy]]. | ||
| + | === Popular misconceptions === | ||
| + | The highly characteristic metal [[Bar (counter)|counters]] of traditional [[France|French]] [[Bar (establishment)|bars]] are often referred to as '''zinc bars''' or vaguely '''zinc''', but actually zinc has never been used for this purpose and the counters are really made of an alloy of [[lead]] and [[tin]]. | ||
| − | + | ==History== | |
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| − | ==History == | ||
[[Image:ZincMetalUSGOV.jpg|thumb|left|Zinc]] | [[Image:ZincMetalUSGOV.jpg|thumb|left|Zinc]] | ||
| − | Zinc alloys have been used for centuries, as brass goods dating to [[1000s B.C.E.|1000]] | + | In ancient [[India]] the production of Zinc metal was very common.Many mine sites of Zawarmaala were active even during 1300-1000 BC.There are references of medicinal uses of zinc in the [[Charaka Samhita]] 300 BC.The [[Rasa Ratna Samuccaya]] (800 C.E.) explains the existence of two types of ores for Zinc metal, one of which is ideal for metal extraction while the other is used for medicinal purpose [http://metalrg.iisc.ernet.in/~wootz/heritage/zn.html Ref]. Zinc alloys have been used for centuries, as brass goods dating to [[1000s B.C.E.|1000]]–[[1400s B.C.E.|1400 B.C.E.]] have been found in [[Israel (region)|Israel]] and zinc objects with 87% zinc have been found in prehistoric [[Transylvania]]. Because of the low boiling point and high chemical reactivity of this metal (isolated zinc would tend to go up the chimney rather than be captured), the true nature of this metal was not understood in ancient times. |
The manufacture of [[brass]] was known to the [[Ancient Rome|Romans]] by about [[30 B.C.E.]], using a technique where [[calamine]] and [[copper]] were heated together in a crucible. The [[zinc oxide]]s in calamine were reduced, and the free zinc metal was trapped by the copper, forming an [[alloy]]. The resulting [[calamine brass]] was either cast or hammered into shape. | The manufacture of [[brass]] was known to the [[Ancient Rome|Romans]] by about [[30 B.C.E.]], using a technique where [[calamine]] and [[copper]] were heated together in a crucible. The [[zinc oxide]]s in calamine were reduced, and the free zinc metal was trapped by the copper, forming an [[alloy]]. The resulting [[calamine brass]] was either cast or hammered into shape. | ||
| − | Smelting and extraction of impure forms of zinc was being accomplished as early as | + | Smelting and extraction of impure forms of zinc was being accomplished as early as [[1000]] AD in [[India]] and [[China]].In the West, impure zinc as a remnant in melting ovens was known since Antiquity, but usually thrown away as worthless. Strabo mentions it as ''pseudo-arguros'' "mock silver". The [[Berne Zinc tablet]] is a votive plaque dating to [[Roman Gaul]], probably made from such zinc remnants. The discovery of pure metallic zinc is most often credited to the German [[Andreas Sigismund Marggraf|Andreas Marggraf]], in the year [[1746]], though the whole story is disputed. |
| − | + | In 1597 C.E. , Libavius , a metallurgist in England received some quantity of Zinc metal in its pure form which was unknown to the west till then.The proof of the ignorance of this metal can be gauged from the fact that till 1751 C.E. [[Postlewayt]]'s Universal Dictionary (the most authentic source of all technological information in Europe) did not mention anything on Zinc.Libavius named it as Indian / Malabar Lead.[[Paracelsus]] ([[1616]]) was credited to have given the name "Zinc" for this "Malabar / Indian" lead . | |
| − | + | In [[1738]], [[William Champion (metallurgist)|William Champion]] is credited with patenting in [[Britain]] a process to extract zinc from calamine in a smelter, a technology he acquired after visiting Zawar Zinc mines in [[Rajasthan]]. His first patent was rejected by the patent court on grounds of plagiarisng the technology common in India.However he was granted the patent on his second submission of patent approval. | |
Before the discovery of the [[zinc sulfide]] [[flotation]] technique, [[calamine]] was the mineral source of zinc metal. | Before the discovery of the [[zinc sulfide]] [[flotation]] technique, [[calamine]] was the mineral source of zinc metal. | ||
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== Biological role == | == Biological role == | ||
| − | Zinc is an essential element, necessary for sustaining all life. It is estimated that 3000 of the hundreds of thousands of proteins in the human body contain zinc. | + | Zinc is an essential element, necessary for sustaining all life. It is estimated that 3000 of the hundreds of thousands of proteins in the human body contain zinc [[prosthetic groups]]. In addition, there are over a dozen types of cells in the human body that secrete zinc ions, and the roles of these secreted zinc signals in medicine and health are now being actively studied. Intriguingly, brain cells in the mammalian forebrain are one type of cell that secretes zinc, along with its other neuronal messenger substances. Cells in the salivary gland, prostate, immune system and intestine are other types that secrete zinc. |
| − | ===Food | + | ===Food sources=== |
| − | + | Zinc is found in oysters, and to a far lesser degree in most animal proteins, beans, nuts, whole grains, pumpkin seeds and sunflower seeds. [[Phytates]], which are found in whole grain breads, cereals, legumes and other products, have been known to decrease zinc absorption. Clinical studies have found that zinc, combined with [[antioxidants]], may delay progression of age-related [[macular degeneration]], but the effect is extremely small and not likely to be clinically important. Significant dietry intake of zinc has also recently been shown to impede the onset of flu. [[Soil conservation]] analyzes the vegetative uptake of naturally occurring zinc in many soil types. | |
| − | ===Zinc | + | ===Zinc deficiency=== |
| − | Zinc deficiency | + | Zinc deficiency results from inadequate intake of zinc, or inadequate absorption of zinc into the body. Signs of zinc deficiency includes hair loss, [[skin]] lesions, [[diarrhea]], wasting of body tissues, and, eventually, death. Eyesight, taste, smell and memory are also connected with zinc and a deficiency in zinc can cause malfunctions of these organs and functions. Congenital abnormalities causing Zinc deficiency may lead to a disease called [[Acrodermatitis enteropathica]]. |
| − | Obtaining a sufficient zinc intake during [[pregnancy]] and in young children is a very real problem, especially among those who cannot afford a good | + | Obtaining a sufficient zinc intake during [[pregnancy]] and in young children is a very real problem, especially among those who cannot afford a good and varied diet. [[Brain]] development is stunted by zinc insufficiency in utero and in youth. Teenage boys require 11 milligrams of zinc. |
| − | + | ===Zinc toxicity=== | |
| + | Even though zinc is an essential requirement for a healthy body, too much zinc can be harmful. Excessive absorption of zinc can also suppress copper and iron absorption. On the other hand, the free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish. The Free Ion Activity Model (FIAM) is well-established in the literature, and shows that just micromolar amounts of the free ion kills some organisms. A recent example of 6 micromolar killing 93% of all daphnia in water is in Muyssen et al., (Aquat Toxicol. 2006). Swallowing an American one cent piece (98% zinc) can also cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach (Bothwell and Mair, PEDIATRICS 2003) whereas the British penny is made from copper-plated steel. Zinc toxicity, mostly in the form of the ingestion of US pennies minted after 1982, is commonly fatal in dogs where it causes a severe [[hemolytic anemia]] (Stowe CM, Nelson R, Werdin R, et al: Zinc phosphide poisoning | ||
| + | in dogs. JAVMA 173:270, 1978) | ||
| − | === | + | ===Immune system=== |
| − | + | Zinc salts are effective against pathogens in direct application. Gastrointestinal infections are also strongly attenuated by ingestion of zinc, and this effect could be due to direct antimicrobial action of the zinc ions in the GI tract, or to absorption of the zinc and re-release from immune cells (all granulocytes secrete zinc) or both. | |
| − | + | The direct effect of zinc (as in lozenges) on bacteria and viruses is also well-established, and has been used since at least 2000 B.C.E., from when zinc salts in palliative salves are documented. However, exactly how to deliver zinc salts against pathogens without injuring one's own tissues is still being investigated. | |
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| − | == | + | == Abundance == |
| − | + | :''See also: [[:Category:Zinc minerals|Zinc minerals]] | |
| − | + | Zinc is the 23rd most abundant element in the [[Earth's crust]]. The most heavily mined [[ore]]s (sphalerite) tend to contain roughly 10% [[iron]] as well as 40-50% zinc. Minerals from which zinc is extracted include [[sphalerite]] (zinc sulfide), [[smithsonite]] (zinc carbonate), [[hemimorphite]] (zinc silicate), and [[franklinite]] (a zinc spinel). | |
| − | Zinc is the 23rd most abundant element in the | ||
== Zinc production == | == Zinc production == | ||
| − | There are zinc mines throughout the world, with the largest producers being [[Australia]], [[Canada]], [[China]], [[Peru]] and the [[U.S.A.]] Mines in [[Europe]] include Vieille Montagne in [[Belgium]], Tara in [[Ireland]], and Zinkgruvan in [[Sweden]]. | + | There are zinc mines throughout the world, with the largest producers being [[Australia]], [[Canada]], [[China]], [[Peru]] and the [[U.S.A.]] Mines in [[Europe]] include Vieille Montagne in [[Belgium]], [[Hill of Tara|Tara]], Galmoy and Lisheen in [[Ireland]], and Zinkgruvan in [[Sweden]]. |
| − | Zinc metal is produced using [[extractive metallurgy]]. [[Zinc sulfide]] ([[sphalerite]]) minerals are concentrated using the [[froth flotation]] method and then usually roasted using [[pyrometallurgy]] to oxidise the zinc sulfide to zinc oxide. The zinc oxide is leached in sulfuric acid | + | Zinc metal is produced using [[extractive metallurgy]]. [[Zinc sulfide]] ([[sphalerite]]) minerals are concentrated using the [[froth flotation]] method and then usually roasted using [[pyrometallurgy]] to oxidise the zinc sulfide to zinc oxide. The zinc oxide is leached in several stages of increasingly stronger sulfuric acid. Iron is usually rejected as Jarosite or goethite, removing other impurities at the same time. The final purification uses zinc dust to remove copper, cadmium and cobalt. The metal is then extracted from the solution by electrowinning as cathodic deposits. Zinc cathodes can be directly cast or alloyed with aluminium. |
Another process to produce zinc is flash smelting, a pyrometallurgical process. Then zinc oxide is obtained, usually producing zinc of lesser quality than the hydrometallurgical process. | Another process to produce zinc is flash smelting, a pyrometallurgical process. Then zinc oxide is obtained, usually producing zinc of lesser quality than the hydrometallurgical process. | ||
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== Compounds == | == Compounds == | ||
| − | [[Zinc oxide]] is perhaps the best known and most widely used zinc compound, as it makes a good base for white pigments in paint. It also finds industrial use in the rubber industry, and is sold as opaque [[sunscreen]]. A variety of other zinc compounds find use industrially, such as [[zinc chloride]] (in deodorants), zinc sulfide (in luminescent paints), and zinc methyl in the organic laboratory. Roughly one quarter of all zinc output is consumed in the form of zinc compounds. | + | :''See also: [[:category:Zinc compounds|Zinc compounds]] |
| + | [[Zinc oxide]] is perhaps the best known and most widely used zinc compound, as it makes a good base for white pigments in paint. It also finds industrial use in the rubber industry, and is sold as opaque [[sunscreen]]. A variety of other zinc compounds find use industrially, such as [[zinc chloride]] (in deodorants), [[zinc sulfide]] (in luminescent paints), and zinc methyl or [[zincdiethyl]] in the organic laboratory. Roughly one quarter of all zinc output is consumed in the form of zinc compounds. | ||
== Isotopes == | == Isotopes == | ||
| − | Naturally occurring zinc is composed of the | + | Naturally occurring zinc is composed of the 5 stable [[isotope]]s <sup>64</sup>Zn, <sup>66</sup>Zn, <sup>67</sup>Zn, <sup>68</sup>Zn, and <sup>70</sup>Zn with <sup>64</sup>Zn being the most abundant (48.6% [[natural abundance]]). 21 [[radioisotope]]s have been characterised with the most abundant and stable being <sup>65</sup>Zn with a [[half-life]] of 244.26 days, and <sup>72</sup>Zn with a half-life of 46.5 hours. All of the remaining [[radioactive]] isotopes have half-lives that are less than 14 hours and the majority of these have half lives that are less than 1 second. This element also has 4 [[meta state]]s. |
| + | |||
| + | Zinc has been proposed as a "[[Salted bomb|salting]]" material for [[nuclear weapon]]s ([[cobalt]] is another, better-known salting material). A jacket of [[Isotope separation|isotopically enriched]] <sup>64</sup>Zn, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope Zn-65 with a half-life of 244 days and produce approximately 2.27 [[MeV]] of [[Gamma ray|gamma radiation]], significantly increasing the radioactivity of the weapon's [[Nuclear fallout|fallout]] for several days. Such a weapon is not known to have ever been built, tested, or used. | ||
== Precautions == | == Precautions == | ||
| − | Metallic zinc is not considered to be toxic, but | + | Metallic zinc is not considered to be toxic, but free zinc ions in solution (like copper or iron ions) are highly toxic. There is also a condition called ''zinc shakes'' or ''zinc chills'' (see [[metal fume fever]]) that can be induced by the inhalation of freshly formed [[zinc oxide]] formed during the [[welding]] of [[galvanize]]d materials. Excessive intake of zinc can promote deficiency in other [[dietary minerals]]. |
==References== | ==References== | ||
| + | |||
*[http://periodic.lanl.gov/elements/30.html Los Alamos National Laboratory - Zinc] | *[http://periodic.lanl.gov/elements/30.html Los Alamos National Laboratory - Zinc] | ||
== External links == | == External links == | ||
| − | + | ||
| + | *[http://metalrg.iisc.ernet.in/~wootz/heritage/zn.html Indian Contribution] | ||
*[http://www.vanderkrogt.net/elements/elem/zn.html History & Etymology of Zinc] | *[http://www.vanderkrogt.net/elements/elem/zn.html History & Etymology of Zinc] | ||
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*[http://www.webelements.com/webelements/elements/text/Zn/index.html WebElements.com – Zinc] | *[http://www.webelements.com/webelements/elements/text/Zn/index.html WebElements.com – Zinc] | ||
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*[http://www.iza.com/zwo_org/Publications/Discovering/0202.htm Discovering the 8th metal] | *[http://www.iza.com/zwo_org/Publications/Discovering/0202.htm Discovering the 8th metal] | ||
| − | *[http:// | + | *[http://minerals.er.usgs.gov/minerals/pubs/commodity/zinc/ Statistics and Information from the U.S. Geological Survey] |
| + | *[http://www.organic-chemistry.org/chemicals/reductions/zinc-zn.shtm Reducing Agents > Zinc] | ||
[[Category:Physical sciences]] | [[Category:Physical sciences]] | ||
[[Category:Chemistry]] | [[Category:Chemistry]] | ||
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Revision as of 06:25, 22 July 2006
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| General | ||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Name, Symbol, Number | zinc, Zn, 30 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Chemical series | transition metals | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Group, Period, Block | 12, 4, d | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Appearance | bluish pale gray 
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic mass | 65.409(4) g/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Electron configuration | [Ar] 3d10 4s2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Electrons per shell | 2, 8, 18, 2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Physical properties | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Phase | solid | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Density (near r.t.) | 7.14 g/cm³ | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Liquid density at m.p. | 6.57 g/cm³ | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Melting point | 692.68 K (419.53 °C, 787.15 °F) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Boiling point | 1180 K (907 °C, 1665 °F) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Heat of fusion | 7.32 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Heat of vaporization | 123.6 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Heat capacity | (25 °C) 25.390 J/(mol·K) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic properties | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Crystal structure | hexagonal | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Oxidation states | 2 (amphoteric oxide) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Electronegativity | 1.65 (Pauling scale) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Ionization energies (more) |
1st: 906.4 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||
| 2nd: 1733.3 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| 3rd: 3833 kJ/mol | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic radius | 135 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Atomic radius (calc.) | 142 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Covalent radius | 131 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Van der Waals radius | 139 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Miscellaneous | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Magnetic ordering | diamagnetic | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Electrical resistivity | (20 °C) 59.0 nΩ·m | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Thermal conductivity | (300 K) 116 W/(m·K) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Thermal expansion | (25 °C) 30.2 µm/(m·K) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Speed of sound (thin rod) | (r.t.) (rolled) 3850 m/s | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Speed of sound (thin rod) | (r.t.) 108 m/s | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Shear modulus | 43 GPa | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Bulk modulus | 70 GPa | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Poisson ratio | 0.25 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Mohs hardness | 2.5 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Brinell hardness | 412 MPa | |||||||||||||||||||||||||||||||||||||||||||||||||||
| CAS registry number | 7440-66-6 | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Notable isotopes | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||
Zinc (from German zink) is a chemical element in the periodic table that has the symbol Zn and atomic number 30.
Notable characteristics
Zinc is a moderately reactive bluish-white metal that tarnishes in moist air producing a layer of carbonate. It reacts with acids and alkalis and other non-metals. If not completely pure, zinc reacts with dilute acids to release hydrogen. The one common oxidation state of zinc is +2.
Applications
Zinc is the fourth most common metal in use, trailing only iron, aluminium, and copper in annual production.
- Zinc is used to galvanize steel to prevent corrosion.
- Zinc is used to Parkerize steel to prevent rust and corrosion
- Zinc is used in alloys such as brass, nickelled silver, typewriter metal, various soldering formulas and German silver.
- Zinc is the primary metal used in making American cents since 1982.
- Zinc is used in die casting notably in the automobile industry.
- Zinc is used as part of the containers of batteries.
- Zinc is used in contemporary pipe organ building as a substitute for the classic lead/tin alloy in pipes sounding the lowest (pedal) tones, as it is tonally almost indistinguishable from lead/tin at those pitches, and has the added advantages of being much more economical and lighter in weight. Even the best organ builders will use zinc in this capacity.
- Zinc oxide is used as a white pigment in watercolours or paints, and as an activator in the rubber industry. As an over-the-counter ointment, it is applied as a thin coating on the exposed skin of the face or nose to prevent dehydration of the area of skin. It can protect against sunburn in the summer and windburn in the winter. Applied thinly to a baby's diaper area (perineum) with each diaper change, it can protect against rash. As determined in the Age-Related Eye Disease Study, it's part of an effective treatment for age-related macular degeneration in some cases.
- Zinc is the fourth common material used in metal wall tiles, and is used for its germicidal properties in kitchens[1].
- Zinc chloride is used as a deodorant and can also be used as a wood preservative.
- Zinc sulfide is used in luminescent pigments such as on the hands of clocks and other items that glow in the dark.
- Zinc methyl (Zn(CH3)2) is used in a number of organic syntheses.
- Zinc stearate is a lubricative plastic additive.
- Lotions made of calamine, a mix of Zn-(hydroxy-)carbonates and silicates, are used to treat skin rash.
- Zinc metal is included in most single tablet over-the-counter daily vitamin and mineral supplements. It is believed to possess anti-oxidant properties, which protect against premature aging of the skin and muscles of the body. In larger amounts, taken as zinc alone in other proprietaries, it is believed by some to speed up the healing process after an injury. Preparations include zinc acetate and zinc gluconate.
- Zinc gluconate glycine and zinc acetate are also used in throat lozenges in an attempt to remedy the common cold.[2]
- Zinc is used as the anode or fuel of the Zinc-air battery/Fuel Cell providing the basis of the Zinc Economy.
Popular misconceptions
The highly characteristic metal counters of traditional French bars are often referred to as zinc bars or vaguely zinc, but actually zinc has never been used for this purpose and the counters are really made of an alloy of lead and tin.
History
In ancient India the production of Zinc metal was very common.Many mine sites of Zawarmaala were active even during 1300-1000 BC.There are references of medicinal uses of zinc in the Charaka Samhita 300 BC.The Rasa Ratna Samuccaya (800 C.E.) explains the existence of two types of ores for Zinc metal, one of which is ideal for metal extraction while the other is used for medicinal purpose Ref. Zinc alloys have been used for centuries, as brass goods dating to 1000–1400 B.C.E. have been found in Israel and zinc objects with 87% zinc have been found in prehistoric Transylvania. Because of the low boiling point and high chemical reactivity of this metal (isolated zinc would tend to go up the chimney rather than be captured), the true nature of this metal was not understood in ancient times.
The manufacture of brass was known to the Romans by about 30 B.C.E., using a technique where calamine and copper were heated together in a crucible. The zinc oxides in calamine were reduced, and the free zinc metal was trapped by the copper, forming an alloy. The resulting calamine brass was either cast or hammered into shape.
Smelting and extraction of impure forms of zinc was being accomplished as early as 1000 C.E. in India and China.In the West, impure zinc as a remnant in melting ovens was known since Antiquity, but usually thrown away as worthless. Strabo mentions it as pseudo-arguros "mock silver". The Berne Zinc tablet is a votive plaque dating to Roman Gaul, probably made from such zinc remnants. The discovery of pure metallic zinc is most often credited to the German Andreas Marggraf, in the year 1746, though the whole story is disputed.
In 1597 C.E. , Libavius , a metallurgist in England received some quantity of Zinc metal in its pure form which was unknown to the west till then.The proof of the ignorance of this metal can be gauged from the fact that till 1751 C.E. Postlewayt's Universal Dictionary (the most authentic source of all technological information in Europe) did not mention anything on Zinc.Libavius named it as Indian / Malabar Lead.Paracelsus (1616) was credited to have given the name "Zinc" for this "Malabar / Indian" lead .
In 1738, William Champion is credited with patenting in Britain a process to extract zinc from calamine in a smelter, a technology he acquired after visiting Zawar Zinc mines in Rajasthan. His first patent was rejected by the patent court on grounds of plagiarisng the technology common in India.However he was granted the patent on his second submission of patent approval.
Before the discovery of the zinc sulfide flotation technique, calamine was the mineral source of zinc metal.
Biological role
Zinc is an essential element, necessary for sustaining all life. It is estimated that 3000 of the hundreds of thousands of proteins in the human body contain zinc prosthetic groups. In addition, there are over a dozen types of cells in the human body that secrete zinc ions, and the roles of these secreted zinc signals in medicine and health are now being actively studied. Intriguingly, brain cells in the mammalian forebrain are one type of cell that secretes zinc, along with its other neuronal messenger substances. Cells in the salivary gland, prostate, immune system and intestine are other types that secrete zinc.
Food sources
Zinc is found in oysters, and to a far lesser degree in most animal proteins, beans, nuts, whole grains, pumpkin seeds and sunflower seeds. Phytates, which are found in whole grain breads, cereals, legumes and other products, have been known to decrease zinc absorption. Clinical studies have found that zinc, combined with antioxidants, may delay progression of age-related macular degeneration, but the effect is extremely small and not likely to be clinically important. Significant dietry intake of zinc has also recently been shown to impede the onset of flu. Soil conservation analyzes the vegetative uptake of naturally occurring zinc in many soil types.
Zinc deficiency
Zinc deficiency results from inadequate intake of zinc, or inadequate absorption of zinc into the body. Signs of zinc deficiency includes hair loss, skin lesions, diarrhea, wasting of body tissues, and, eventually, death. Eyesight, taste, smell and memory are also connected with zinc and a deficiency in zinc can cause malfunctions of these organs and functions. Congenital abnormalities causing Zinc deficiency may lead to a disease called Acrodermatitis enteropathica.
Obtaining a sufficient zinc intake during pregnancy and in young children is a very real problem, especially among those who cannot afford a good and varied diet. Brain development is stunted by zinc insufficiency in utero and in youth. Teenage boys require 11 milligrams of zinc.
Zinc toxicity
Even though zinc is an essential requirement for a healthy body, too much zinc can be harmful. Excessive absorption of zinc can also suppress copper and iron absorption. On the other hand, the free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish. The Free Ion Activity Model (FIAM) is well-established in the literature, and shows that just micromolar amounts of the free ion kills some organisms. A recent example of 6 micromolar killing 93% of all daphnia in water is in Muyssen et al., (Aquat Toxicol. 2006). Swallowing an American one cent piece (98% zinc) can also cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach (Bothwell and Mair, PEDIATRICS 2003) whereas the British penny is made from copper-plated steel. Zinc toxicity, mostly in the form of the ingestion of US pennies minted after 1982, is commonly fatal in dogs where it causes a severe hemolytic anemia (Stowe CM, Nelson R, Werdin R, et al: Zinc phosphide poisoning in dogs. JAVMA 173:270, 1978)
Immune system
Zinc salts are effective against pathogens in direct application. Gastrointestinal infections are also strongly attenuated by ingestion of zinc, and this effect could be due to direct antimicrobial action of the zinc ions in the GI tract, or to absorption of the zinc and re-release from immune cells (all granulocytes secrete zinc) or both.
The direct effect of zinc (as in lozenges) on bacteria and viruses is also well-established, and has been used since at least 2000 B.C.E., from when zinc salts in palliative salves are documented. However, exactly how to deliver zinc salts against pathogens without injuring one's own tissues is still being investigated.
Abundance
- See also: Zinc minerals
Zinc is the 23rd most abundant element in the Earth's crust. The most heavily mined ores (sphalerite) tend to contain roughly 10% iron as well as 40-50% zinc. Minerals from which zinc is extracted include sphalerite (zinc sulfide), smithsonite (zinc carbonate), hemimorphite (zinc silicate), and franklinite (a zinc spinel).
Zinc production
There are zinc mines throughout the world, with the largest producers being Australia, Canada, China, Peru and the U.S.A. Mines in Europe include Vieille Montagne in Belgium, Tara, Galmoy and Lisheen in Ireland, and Zinkgruvan in Sweden. Zinc metal is produced using extractive metallurgy. Zinc sulfide (sphalerite) minerals are concentrated using the froth flotation method and then usually roasted using pyrometallurgy to oxidise the zinc sulfide to zinc oxide. The zinc oxide is leached in several stages of increasingly stronger sulfuric acid. Iron is usually rejected as Jarosite or goethite, removing other impurities at the same time. The final purification uses zinc dust to remove copper, cadmium and cobalt. The metal is then extracted from the solution by electrowinning as cathodic deposits. Zinc cathodes can be directly cast or alloyed with aluminium.
Another process to produce zinc is flash smelting, a pyrometallurgical process. Then zinc oxide is obtained, usually producing zinc of lesser quality than the hydrometallurgical process. Zinc oxide treatment has much fewer applications, but high grade deposits have been successful in producing zinc from zinc oxides and zinc carbonates using hydrometallurgy.
Compounds
- See also: Zinc compounds
Zinc oxide is perhaps the best known and most widely used zinc compound, as it makes a good base for white pigments in paint. It also finds industrial use in the rubber industry, and is sold as opaque sunscreen. A variety of other zinc compounds find use industrially, such as zinc chloride (in deodorants), zinc sulfide (in luminescent paints), and zinc methyl or zincdiethyl in the organic laboratory. Roughly one quarter of all zinc output is consumed in the form of zinc compounds.
Isotopes
Naturally occurring zinc is composed of the 5 stable isotopes 64Zn, 66Zn, 67Zn, 68Zn, and 70Zn with 64Zn being the most abundant (48.6% natural abundance). 21 radioisotopes have been characterised with the most abundant and stable being 65Zn with a half-life of 244.26 days, and 72Zn with a half-life of 46.5 hours. All of the remaining radioactive isotopes have half-lives that are less than 14 hours and the majority of these have half lives that are less than 1 second. This element also has 4 meta states.
Zinc has been proposed as a "salting" material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched 64Zn, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope Zn-65 with a half-life of 244 days and produce approximately 2.27 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several days. Such a weapon is not known to have ever been built, tested, or used.
Precautions
Metallic zinc is not considered to be toxic, but free zinc ions in solution (like copper or iron ions) are highly toxic. There is also a condition called zinc shakes or zinc chills (see metal fume fever) that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials. Excessive intake of zinc can promote deficiency in other dietary minerals.
ReferencesISBN links support NWE through referral fees
External links
- Indian Contribution
- History & Etymology of Zinc
- WebElements.com – Zinc
- Discovering the 8th metal
- Statistics and Information from the U.S. Geological Survey
- Reducing Agents > Zinc
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