Editing Group 12 element (section)

==Physical and atomic properties==
Like other [[group (periodic table)|groups]] of the [[periodic table]], the members of group 12 show patterns in its electron configuration, especially the outermost shells, which result in trends in their chemical behavior:
{| class="wikitable" style="white-space:nowrap;"
|-
!''[[Atomic number|Z]]'' !! [[Chemical element|Element]] !! Electrons per [[Electron shell|shell]]
|-
| 30 || zinc || 2, 8, 18, 2
|-
| 48 || cadmium || 2, 8, 18, 18, 2
|-
| 80 || mercury || 2, 8, 18, 32, 18, 2
|-
| 112 || copernicium || 2, 8, 18, 32, 32, 18, 2<br/>(predicted)
|}

The group 12 elements are all soft, [[diamagnetic]], [[divalent]] metals. They have the lowest melting points among all [[transition metals]].<ref name=ZincMetalProps/> Zinc is bluish-white and lustrous,<ref name="CRCp4-41">{{cite book |editor=David R. Lide |title=Handbook of Chemistry and Physics |edition=87th |year=2006 |publisher=CRC Press, Taylor & Francis Group |location=Boca Raton, Florida |isbn=978-0-8493-0487-3 |url=https://books.google.com/books?id=WDll8hA006AC |page=4{{hyphen}}41}}<!-- sic "-" not a range! --></ref> though most common commercial grades of the metal have a dull finish.<ref name="Heiserman1992p123">{{cite book |last=Heiserman |first=David L. |year=1992 |title=Exploring Chemical Elements and their Compounds |location=New York |publisher=TAB Books |isbn=978-0-8306-3018-9 |chapter=Element 30: Zinc |chapter-url=https://books.google.com/books?id=24l-Cpal9oIC |url=https://archive.org/details/exploringchemica01heis |page=123}}</ref> Zinc is also referred to in nonscientific contexts as ''[[spelter]]''.<ref name="Ingalls"/> 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.<ref name=CRC>Hammond, C. R [http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elements.pdf The Elements] in {{RubberBible86th}}</ref>

The table below is a summary of the key physical properties of the group 12 elements. The data for [[copernicium]] is based on relativistic density-functional theory simulations.<ref name=":0">{{Cite journal|last1=Mewes|first1=Jan-Michael|last2=Smits|first2=Odile R.|last3=Kresse|first3=Georg |last4=Schwerdtfeger|first4=Peter|date=2019|title=Copernicium: A Relativistic Noble Liquid |journal=Angewandte Chemie|volume=131|issue=50|pages=18132–18136 |doi=10.1002/ange.201906966|bibcode=2019AngCh.13118132M |issn=1521-3757 |doi-access=free}}</ref>

{| class="wikitable centered" style="text-align:center;"
|+Properties of the Group 12 elements| Properties of the group 12 elements
! Name
! Zinc
! Cadmium
! Mercury
! Copernicium
|-
| style="background:lightgrey; text-align:left;"|[[Melting point]]
| 693 [[Kelvin|K]] (420 [[Celsius|°C]]) || 594 K (321&nbsp;°C) || 234 K (−39&nbsp;°C) || 283±11 K<ref name=":0" /> (10&nbsp;°C)
|-
| style="background:lightgrey; text-align:left;"|[[Boiling point]]
| 1180 K (907&nbsp;°C) || 1040 K (767&nbsp;°C) || 630 K (357&nbsp;°C) || 340±10 K<ref name=":0" /> (60&nbsp;°C)
|-
| style="background:lightgrey; text-align:left;"|[[Density]]
| 7.14&nbsp;g·cm<sup>−3</sup> || 8.65&nbsp;g·cm<sup>−3</sup> || 13.534&nbsp;g·cm<sup>−3</sup> || 14.0&nbsp;g·cm<sup>−3</sup> <ref name=":0" />
|-
| style="background:lightgrey; text-align:left;"|Appearance
| silvery bluish-gray || silver-gray || silvery || ?
|-
| style="background:lightgrey; text-align:left;"|[[Atomic radius]]
| 135 pm || 155 pm || 150 pm || ? 147 pm
|}

Zinc is somewhat less dense than [[iron]] and has a hexagonal [[crystal structure]].{{sfn|Lehto|1968|p=826}} The metal is hard and brittle at most temperatures but becomes malleable between {{convert|100 and 150|C|F}}.<ref name="CRCp4-41"/><ref name="Heiserman1992p123"/> Above {{convert|210|C|F}}, the metal becomes brittle again and can be pulverized by beating.<ref>{{Cite book|title=The Useful Metals and Their Alloys |url=https://archive.org/details/usefulmetalsand00scofgoog|first=John|last=Scoffern|author-link=John Scoffern|pages=[https://archive.org/details/usefulmetalsand00scofgoog/page/n613 591]–603|publisher=Houlston and Wright|year=1861 |access-date=2009-04-06}}</ref> Zinc is a fair [[electrical conductivity|conductor of electricity]].<ref name="CRCp4-41"/> For a metal, zinc has relatively low melting ({{convert|419.5|C|F|disp=comma}}) and boiling points ({{convert|907|C|F|disp=comma}}).<ref name=ZincMetalProps>{{cite web |title=Zinc Metal Properties |url=http://www.galvanizeit.org/aga/designing-fabricating/design-considerations/zinc-metal-properties |publisher=American Galvanizers Association |year=2008 |access-date=2009-02-15 |url-status=dead |archive-url=https://web.archive.org/web/20090221111748/http://galvanizeit.org/aga/designing-fabricating/design-considerations/zinc-metal-properties |archive-date=February 21, 2009 }}</ref> Cadmium is similar in many respects to zinc but forms [[Complex (chemistry)|complex]] compounds.<ref>{{cite book |publisher=Walter de Gruyter|year=1985|edition=91–100|pages=1056–1057|isbn=978-3-11-007511-3 |title=Lehrbuch der Anorganischen Chemie|first1=Arnold F.|last1=Holleman|last2=Wiberg|first2=Egon |last3=Wiberg|first3=Nils|language=de|chapter=Cadmium}}</ref> Unlike other metals, cadmium is resistant to [[corrosion]] 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 not [[Flammability|flammable]]; however, in its powdered form it may burn and release toxic fumes.<ref name="ATSDR">{{cite web |title=Case Studies in Environmental Medicine (CSEM) Cadmium |url=http://www.atsdr.cdc.gov/csem/cadmium/cdcontents.html |publisher=Agency for Toxic Substances and Disease Registry |access-date=May 30, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110203222234/http://www.atsdr.cdc.gov/csem/cadmium/cdcontents.html |archive-date=February 3, 2011 }}</ref> Mercury has an exceptionally low melting temperature for a d-block metal. A complete explanation of this fact requires a deep excursion into [[quantum 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 to [[noble 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 attractive [[Coulomb's law|Coulomb interaction]] of the 6s shell and the nucleus (see [[lanthanide 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 strong [[metallic bonds]].<ref name="Norrby">{{cite journal |author=Norrby, L.J.|title=Why is mercury liquid? Or, why do relativistic effects not get into chemistry textbooks?| journal= Journal of Chemical Education|volume=68|issue=2|page=110 |year=1991 |doi=10.1021/ed068p110 |bibcode=1991JChEd..68..110N}}</ref><ref>{{cite web|title=Why is mercury a liquid at STP? |url=http://antoine.frostburg.edu/chem/senese/101/periodic/faq/why-is-mercury-liquid.shtml|access-date=2009-07-07}}</ref>

Zinc, cadmium and mercury form a large range of [[alloy]]s. Among the zinc containing ones, [[brass]] is an alloy of zinc and [[copper]]. Other metals long known to form binary alloys with zinc are [[aluminium]], [[antimony]], [[bismuth]], [[gold]], iron, [[lead]], mercury, [[silver]], [[tin]], [[magnesium]], [[cobalt]], [[nickel]], [[tellurium]] and [[sodium]].<ref name="Ingalls">{{Cite book|title=Production and Properties of Zinc: A Treatise on the Occurrence and Distribution of Zinc Ore, the Commercial and Technical Conditions Affecting the Production of the Spelter, Its Chemical and Physical Properties and Uses in the Arts, Together with a Historical and Statistical Review of the Industry|last=Ingalls|first=Walter Renton |publisher=The Engineering and Mining Journal|year=1902|pages=[https://archive.org/details/productionandpr01ingagoog/page/n332 142]–6 |url=https://archive.org/details/productionandpr01ingagoog}}</ref> While neither zinc nor [[zirconium]] are [[Ferromagnetism|ferromagnetic]], their alloy {{chem|ZrZn|2}} exhibits ferromagnetism below 35&nbsp;[[Kelvin|K]].<ref name="CRCp4-41"/> Cadmium is used in many kinds of [[solder]] and bearing alloys, due to a low [[coefficient of friction]] and fatigue resistance.<ref name="HgCdPb"/> It is also found in some of the lowest-melting alloys, such as [[Wood's metal]].<ref>{{cite book|first1= George Stuart|last1= Brady|first2= George S.|last2= Brady|first3= Henry R.|last3= Clauser|first4 = John A.|last4 = Vaccari|isbn = 978-0-07-136076-0|url = https://books.google.com/books?id=vIhvSQLhhMEC&pg=PA425|title = Materials handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors|publisher = McGraw-Hill Professional|year = 2002| page = 425}}</ref> Because it is a liquid, mercury dissolves other metals and the alloys that are formed are called [[amalgam (chemistry)|amalgams]]. 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 include [[tantalum]], [[tungsten]] and [[platinum]]. [[Sodium amalgam]] is a common reducing agent in [[organic synthesis]], and is also used in [[high-pressure sodium]] lamps. Mercury readily combines with [[aluminium]] to form a [[aluminium amalgam|mercury-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.<ref name="CorrAl">{{cite book |author1=Vargel, C. |author2=Jacques, M. |author3=Schmidt, M. P. | title = Corrosion of Aluminium|year =2004| isbn = 978-0-08-044495-6|publisher = Elsevier |url=https://books.google.com/books?id=NAABS5KrVDYC&pg=PA158|page=158}}</ref>