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Group 12 element
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<h2 id="physical-and-atomic-properties">Physical and atomic properties</h2> <p>Like other <a href="/facts/Group_(periodic_table)/YGBcUabv">groups</a> of the <a href="/facts/Periodic_table/umdGIfUb">periodic table</a>, the members of group 12 show patterns in its electron configuration, especially the outermost shells, which result in trends in their chemical behavior: </p> <table><tbody><tr><th><i><a href="/facts/Atomic_number/bgAr581S">Z</a></i></th><th><a href="/facts/Chemical_element/0jducgWD">Element</a></th><th>Electrons per <a href="/facts/Electron_shell/QxI30eh9">shell</a></th></tr><tr><td>30</td><td>zinc</td><td>2, 8, 18, 2</td></tr><tr><td>48</td><td>cadmium</td><td>2, 8, 18, 18, 2</td></tr><tr><td>80</td><td>mercury</td><td>2, 8, 18, 32, 18, 2</td></tr><tr><td>112</td><td>copernicium</td><td>2, 8, 18, 32, 32, 18, 2(predicted)</td></tr></tbody></table> <p>The group 12 elements are all soft, <a href="/facts/Diamagnetic/dgFavn9K">diamagnetic</a>, <a href="/facts/Divalent/ck7cHByj">divalent</a> metals. They have the lowest melting points among all <a href="/facts/Transition_metals/0slGWoLQ">transition metals</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Zinc is bluish-white and lustrous,<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> though most common commercial grades of the metal have a dull finish.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Zinc is also referred to in nonscientific contexts as <i><a href="/facts/Spelter/IvMLzVS0">spelter</a></i>.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> Cadmium is soft, <a href="/facts/Malleable/SBJsahEk">malleable</a>, <a href="/facts/Ductile/SBJsahEk">ductile</a>, 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.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p><p>The table below is a summary of the key physical properties of the group 12 elements. The data for <a href="/facts/Copernicium/EhgyBkg0">copernicium</a> is based on relativistic density-functional theory simulations.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> Properties of the group 12 elements<table><tbody><tr><th>Name</th><th>Zinc</th><th>Cadmium</th><th>Mercury</th><th>Copernicium</th></tr><tr><td><a href="/facts/Melting_point/MY0w0h0k">Melting point</a></td><td>693 <a href="/facts/Kelvin/E3trzC4C">K</a> (420 <a href="/facts/Celsius/okAEu1CA">°C</a>)</td><td>594 K (321 °C)</td><td>234 K (−39 °C)</td><td>283±11 K<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> (10 °C)</td></tr><tr><td><a href="/facts/Boiling_point/E2BK9QoS">Boiling point</a></td><td>1180 K (907 °C)</td><td>1040 K (767 °C)</td><td>630 K (357 °C)</td><td>340±10 K<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> (60 °C)</td></tr><tr><td><a href="/facts/Density/92p6hh9I">Density</a></td><td>7.14 g·cm−3</td><td>8.65 g·cm−3</td><td>13.534 g·cm−3</td><td>14.0 g·cm−3 <a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td></tr><tr><td>Appearance</td><td>silvery bluish-gray</td><td>silver-gray</td><td>silvery</td><td>?</td></tr><tr><td><a href="/facts/Atomic_radius/0mQaIJX9">Atomic radius</a></td><td>135 pm</td><td>155 pm</td><td>150 pm</td><td>? 147 pm</td></tr></tbody></table> <p>Zinc is somewhat less dense than <a href="/facts/Iron/QK1JYy8E">iron</a> and has a hexagonal <a href="/facts/Crystal_structure/bJ4bCeHd">crystal structure</a>.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C (212 and 302 °F).<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> Above 210 °C (410 °F), the metal becomes brittle again and can be pulverized by beating.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> Zinc is a fair <a href="/facts/Electrical_conductivity/akyCKvMy">conductor of electricity</a>.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> For a metal, zinc has relatively low melting (419.5 °C, 787.1 °F) and boiling points (907 °C, 1,665 °F).<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> Cadmium is similar in many respects to zinc but forms <a href="/facts/Complex_(chemistry)/1tCyeQUm">complex</a> compounds.<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> Unlike other metals, cadmium is resistant to <a href="/facts/Corrosion/lIC7H4we">corrosion</a> 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 <a href="/facts/Flammability/1QexTQ4T">flammable</a>; however, in its powdered form it may burn and release toxic fumes.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> Mercury has an exceptionally low melting temperature for a d-block metal. A complete explanation of this fact requires a deep excursion into <a href="/facts/Quantum_physics/BRc3Mzgr">quantum physics</a>, 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 <a href="/facts/Noble_gas/j0yHMEAE">noble gas</a> 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 <a href="/facts/Coulomb%27s_law/V0lR5NKv">Coulomb interaction</a> of the 6s shell and the nucleus (see <a href="/facts/Lanthanide_contraction/qulzIb3r">lanthanide contraction</a>). 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. <a href="/facts/Gold/1znknojp">Gold</a> 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 <a href="/facts/Metallic_bonds/Ht958du4">metallic bonds</a>.<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> </p><p>Zinc, cadmium and mercury form a large range of <a href="/facts/Alloy/I7w7WQWR">alloys</a>. Among the zinc containing ones, <a href="/facts/Brass/pe8EHk6x">brass</a> is an alloy of zinc and <a href="/facts/Copper/I8PEE8oX">copper</a>. Other metals long known to form binary alloys with zinc are <a href="/facts/Aluminium/7wmR8jYE">aluminium</a>, <a href="/facts/Antimony/YsA7lVgT">antimony</a>, <a href="/facts/Bismuth/75FLjkoX">bismuth</a>, <a href="/facts/Gold/1znknojp">gold</a>, iron, <a href="/facts/Lead/EYljasJN">lead</a>, mercury, <a href="/facts/Silver/xXe41BGg">silver</a>, <a href="/facts/Tin/obW9mqc3">tin</a>, <a href="/facts/Magnesium/XyIhd2FG">magnesium</a>, <a href="/facts/Cobalt/gqhScEw4">cobalt</a>, <a href="/facts/Nickel/KwMCHYRP">nickel</a>, <a href="/facts/Tellurium/v7QvfIvS">tellurium</a> and <a href="/facts/Sodium/eYuSPu2V">sodium</a>.<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> While neither zinc nor <a href="/facts/Zirconium/y7gsoQFz">zirconium</a> are <a href="/facts/Ferromagnetism/fH3HFnSl">ferromagnetic</a>, their alloy ZrZn2 exhibits ferromagnetism below 35 <a href="/facts/Kelvin/E3trzC4C">K</a>.<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> Cadmium is used in many kinds of <a href="/facts/Solder/GBvJH75t">solder</a> and bearing alloys, due to a low <a href="/facts/Coefficient_of_friction/d0108Rpu">coefficient of friction</a> and fatigue resistance.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> It is also found in some of the lowest-melting alloys, such as <a href="/facts/Wood%27s_metal/Prh7s4ja">Wood's metal</a>.<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> Because it is a liquid, mercury dissolves other metals and the alloys that are formed are called <a href="/facts/Amalgam_(chemistry)/5dRXJyt3">amalgams</a>. 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 <a href="/facts/Tantalum/VwaxMm33">tantalum</a>, <a href="/facts/Tungsten/WYwbNDYX">tungsten</a> and <a href="/facts/Platinum/qJC6lQf7">platinum</a>. <a href="/facts/Sodium_amalgam/NlTRR9eq">Sodium amalgam</a> is a common reducing agent in <a href="/facts/Organic_synthesis/aprl6Iq7">organic synthesis</a>, and is also used in <a href="/facts/High-pressure_sodium/STEH8FgR">high-pressure sodium</a> lamps. Mercury readily combines with <a href="/facts/Aluminium/7wmR8jYE">aluminium</a> to form a <a href="/facts/Aluminium_amalgam/u0CMvoGW">mercury-aluminium amalgam</a> 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.<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> </p> <h2 id="chemistry">Chemistry</h2> <p>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. </p> <h3>Periodic trends</h3> <p>All elements in this group are <a href="/facts/Metal/PT8hNX6R">metals</a>. The similarity of the metallic radii of cadmium and mercury is an effect of the <a href="/facts/Lanthanide_contraction/qulzIb3r">lanthanide contraction</a>. So, the trend in this group is unlike the trend in group 2, the <a href="/facts/Alkaline_earth/Ts4U5zIe">alkaline earths</a>, where metallic radius increases smoothly from top to bottom of the group. All three metals have relatively low melting and boiling points, indicating that the <a href="/facts/Metallic_bond/Ht958du4">metallic bond</a> is relatively weak, with relatively little overlap between the <a href="/facts/Valence_band/2NUALlHJ">valence band</a> and the <a href="/facts/Conduction_band/2NUALlHJ">conduction band</a>.<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> Thus, zinc is close to the boundary between metallic and <a href="/facts/Metalloid/uMFVXuTq">metalloid</a> elements, which is usually placed between <a href="/facts/Gallium/EucevDs9">gallium</a> and <a href="/facts/Germanium/wtoALHGs">germanium</a>, though gallium participates in <a href="/facts/Semi-conductor/zFf3mGTE">semi-conductors</a> such as <a href="/facts/Gallium_arsenide/BakLFjpp">gallium arsenide</a>. </p><p>Zinc and cadmium are <a href="/facts/Electropositivity/H7Vq7Uah">electropositive</a> while mercury is not.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> 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 full <a href="/facts/Electron_shell/QxI30eh9">sub-shell</a>. However, mercury can easily be reduced to the +1 oxidation state; usually, as in the ion Hg2+2, two mercury(I) ions come together to form a metal-metal bond and a <a href="/facts/Diamagnetic/dgFavn9K">diamagnetic</a> species.<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> 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 to <a href="/facts/Calomel/0fucDWnb">calomel</a>. In the solid phase, the rather exotic compound <a href="/facts/Decamethyldizincocene/W8UeUzpb">decamethyldizincocene</a> (Cp*Zn–ZnCp*) is known. </p> <h3>Classification</h3> <p>The elements in group 12 are usually considered to be <a href="/facts/D-block/BbzD5jUU">d-block</a> elements, but not <a href="/facts/Transition_element/0slGWoLQ">transition elements</a> as the d-shell is full. Some authors classify these elements as <a href="/facts/Main-group_element/2AG3QxJl">main-group elements</a> because the <a href="/facts/Valence_electron/mXPA15VP">valence electrons</a> are in ns2 orbitals. Nevertheless, they share many characteristics with the neighboring <a href="/facts/Group_11_element/phumzNJU">group 11 elements</a> 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 the <a href="/facts/Irving-Williams_series/5rkWAJXJ">Irving-Williams series</a> as zinc forms many complexes with the same <a href="/facts/Stoichiometry/I5p9cJzV">stoichiometry</a> as complexes of copper(II), albeit with smaller <a href="/facts/Stability_constants_of_complexes/7b2VkVb2">stability constants</a>.<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> 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 to <a href="/facts/IUPAC/2AV6myCK">IUPAC</a>'s definition of transition metal as <i>an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell</i>,<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> 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, in <a href="/facts/Mercury(IV)_fluoride/BzEKrtX7">mercury(IV) fluoride</a> (though its existence is disputed, as later experiments trying to confirm its synthesis could not find evidence of HgF4).<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a><a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> 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.<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> </p> <h3>Relationship with the alkaline earth metals</h3> <p>Although group 12 lies in the <a href="/facts/D-block/BbzD5jUU">d-block</a> 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 the <a href="/facts/Main-group_element/2AG3QxJl">main-group elements</a>, but is in stark contrast to that of the neighboring <a href="/facts/Group_11_element/phumzNJU">group 11 elements</a> (<a href="/facts/Copper/I8PEE8oX">copper</a>, <a href="/facts/Silver/xXe41BGg">silver</a>, and <a href="/facts/Gold/1znknojp">gold</a>), which also have filled d-subshells in their ground-state <a href="/facts/Electron_configuration/TQjRr22P">electron configuration</a> but behave chemically as transition metals. For example, the bonding in <a href="/facts/Chromium(II)_sulfide/Ks7ykEe4">chromium(II) sulfide</a> (CrS) involves mainly the 3d electrons; that in <a href="/facts/Iron(II)_sulfide/byDMQhD8">iron(II) sulfide</a> (FeS) involves both the 3d and 4s electrons; but that of <a href="/facts/Zinc_sulfide/K8l5AF3K">zinc sulfide</a> (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 of <a href="/facts/Alkaline_earth_metal/Ts4U5zIe">group 2</a>, <a href="/facts/Beryllium/dv295voP">beryllium</a> and <a href="/facts/Magnesium/XyIhd2FG">magnesium</a>, 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 their <a href="/facts/Atomic_radius/0mQaIJX9">atomic radii</a>, <a href="/facts/Ionic_radius/C3dwKrrB">ionic radii</a>, <a href="/facts/Electronegativity/H7Vq7Uah">electronegativities</a>, and also in the structure of their <a href="/facts/Binary_compound/pQ7zq0Cv">binary compounds</a> and their ability to form complex ions with many <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a> and <a href="/facts/Oxygen/acyn6o8r">oxygen</a> <a href="/facts/Ligand/6etB3qeW">ligands</a>, such as complex <a href="/facts/Hydride/v2rlBGMg">hydrides</a> and <a href="/facts/Amine/JvfYJfP6">amines</a>. However, beryllium and magnesium are small atoms, unlike the heavier <a href="/facts/Alkaline_earth_metal/Ts4U5zIe">alkaline earth metals</a> and like the group 12 elements (which have a greater nuclear charge but the same number of <a href="/facts/Valence_electron/mXPA15VP">valence electrons</a>), and the <a href="/facts/Periodic_trend/dI0mkSju">periodic trends</a> down group 2 from beryllium to <a href="/facts/Radium/VWo5gkzn">radium</a> (similar to that of the <a href="/facts/Alkali_metal/IkWbCLk2">alkali metals</a>) 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 the <a href="/facts/D-block_contraction/Pc9awt67">d-block</a> and <a href="/facts/Lanthanide_contraction/qulzIb3r">lanthanide contractions</a>. It is also the d-block and lanthanide contractions that give mercury many of its distinctive properties.<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> </p> Comparison of the properties of the alkaline earth metals and the group 12 elements (predictions for copernicium)<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a><table><tbody><tr><th>Name</th><th>Beryllium</th><th>Magnesium</th><th>Calcium</th><th>Strontium</th><th>Barium</th><th>Radium</th></tr><tr><td><a href="/facts/Valence_electron/mXPA15VP">Valence electron</a> configuration</td><td>2s2</td><td>3s2</td><td>4s2</td><td>5s2</td><td>6s2</td><td>7s2</td></tr><tr><td>Core electron configuration</td><td>[<a href="/facts/Helium/yRul93TG">He</a>]</td><td>[<a href="/facts/Neon/5bF1FwGL">Ne</a>]</td><td>[<a href="/facts/Argon/QX6NRH6d">Ar</a>]</td><td>[<a href="/facts/Krypton/llkNlCke">Kr</a>]</td><td>[<a href="/facts/Xenon/9E3XR69R">Xe</a>]</td><td>[<a href="/facts/Radon/0V9arWKl">Rn</a>]</td></tr><tr><td><a href="/facts/Oxidation_state/W53W6s6V">Oxidation states</a><a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a></td><td>+2, +1</td><td>+2, +1</td><td>+2, +1</td><td>+2, +1</td><td>+2</td><td>+2</td></tr><tr><td><a href="/facts/Melting_point/MY0w0h0k">Melting point</a></td><td>1560 <a href="/facts/Kelvin/E3trzC4C">K</a> (1287 <a href="/facts/Celsius/okAEu1CA">°C</a>)</td><td>923 K (650 °C)</td><td>1115 K (842 °C)</td><td>1050 K (777 °C)</td><td>1000 K (727 °C)</td><td>973 K (700 °C)</td></tr><tr><td><a href="/facts/Boiling_point/E2BK9QoS">Boiling point</a></td><td>2742 K (2469 °C)</td><td>1363 K (1090 °C)</td><td>1757 K (1484 °C)</td><td>1655 K (1382 °C)</td><td>2170 K (1897 °C)</td><td>2010 K (1737 °C)</td></tr><tr><td>Appearance</td><td>white-gray metallic</td><td>shiny gray metallic</td><td>dull silver-gray</td><td>silvery white metallic</td><td>silvery gray</td><td>silvery white metallic</td></tr><tr><td><a href="/facts/Density/92p6hh9I">Density</a></td><td>1.85 g·cm−3</td><td>1.738 g·cm−3</td><td>1.55 g·cm−3</td><td>2.64 g·cm−3</td><td>3.51 g·cm−3</td><td>5.5 g·cm−3</td></tr><tr><td>Pauling <a href="/facts/Electronegativity/H7Vq7Uah">electronegativity</a></td><td>1.57</td><td>1.31</td><td>1.00</td><td>0.95</td><td>0.89</td><td>0.9</td></tr><tr><td><a href="/facts/Atomic_radius/0mQaIJX9">Atomic radius</a></td><td>105 pm</td><td>150 pm</td><td>180 pm</td><td>200 pm</td><td>215 pm</td><td>215 pm</td></tr><tr><td>Crystal <a href="/facts/Ionic_radius/C3dwKrrB">ionic radius</a></td><td>59 pm</td><td>86 pm</td><td>114 pm</td><td>132 pm</td><td>149 pm</td><td>162 pm</td></tr><tr><td><a href="/facts/Flame_test/EcpqRIt7">Flame test</a> color</td><td>white<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a></td><td>brilliant white<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a></td><td>brick-red<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a></td><td>crimson<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></td><td>apple green<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a></td><td>crimson red<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a></td></tr><tr><td><a href="/facts/Organometallic_chemistry/bhqFz2P0">Organometallic chemistry</a></td><td>good</td><td>good</td><td>poor</td><td>very poor</td><td>very poor</td><td>extremely poor</td></tr><tr><td><a href="/facts/Hydroxide/zW0wxpWD">Hydroxide</a></td><td><a href="/facts/Amphoteric/2UrXEsyl">amphoteric</a></td><td><a href="/facts/Base_(chemistry)/M9wA7qeM">basic</a></td><td>basic</td><td>strongly basic</td><td>strongly basic</td><td>strongly basic</td></tr><tr><td><a href="/facts/Oxide/DXtoVe1C">Oxide</a></td><td>amphoteric</td><td>strongly basic</td><td>strongly basic</td><td>strongly basic</td><td>strongly basic</td><td>strongly basic</td></tr><tr><th>Name</th><th>Beryllium</th><th>Magnesium</th><th>Zinc</th><th>Cadmium</th><th>Mercury</th><th>Copernicium</th></tr><tr><td>Valence electron configuration</td><td>2s2</td><td>3s2</td><td>4s2</td><td>5s2</td><td>6s2</td><td>? 7s2</td></tr><tr><td>Core electron configuration</td><td>[He]</td><td>[Ne]</td><td>[Ar]3d10</td><td>[Kr]4d10</td><td>[Xe]4f145d10</td><td>? [Rn]5f146d10</td></tr><tr><td>Oxidation states<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a></td><td>+2, +1</td><td>+2, +1</td><td>+2, +1</td><td>+2, +1</td><td>+2, +1</td><td>? +4, +2, +1, 0<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a><a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a><a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a></td></tr><tr><td>Melting point</td><td>1560 K (1287 °C)</td><td>923 K (650 °C)</td><td>693 K (420 °C)</td><td>594 K (321 °C)</td><td>234 K (−39 °C)</td><td>283±11 K (10 °C)</td></tr><tr><td>Boiling point</td><td>2742 K (2469 °C)</td><td>1363 K (1090 °C)</td><td>1180 K (907 °C)</td><td>1040 K (767 °C)</td><td>630 K (357 °C)</td><td>340±10 K (60 °C)</td></tr><tr><td>Appearance</td><td>white-gray metallic</td><td>shiny gray metallic</td><td>silvery bluish-gray metallic</td><td>silver-gray</td><td>silvery</td><td>?</td></tr><tr><td>Density</td><td>1.85 g·cm−3</td><td>1.738 g·cm−3</td><td>7.14 g·cm−3</td><td>8.65 g·cm−3</td><td>13.534 g·cm−3</td><td>14.0 g·cm−3</td></tr><tr><td>Pauling electronegativity</td><td>1.57</td><td>1.31</td><td>1.65</td><td>1.69</td><td>2.00</td><td>?</td></tr><tr><td>Atomic radius</td><td>105 pm</td><td>150 pm</td><td>135 pm</td><td>155 pm</td><td>150 pm</td><td>? 147 pm<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a></td></tr><tr><td>Crystal ionic radius</td><td>59 pm</td><td>86 pm</td><td>88 pm</td><td>109 pm</td><td>116 pm</td><td>? 75 pm<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a></td></tr><tr><td>Flame test color</td><td>white</td><td>brilliant white</td><td>bluish-green<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a></td><td>?</td><td>?</td><td>?</td></tr><tr><td>Organometallic chemistry</td><td>good</td><td>good</td><td>good</td><td>good</td><td>good</td><td>?</td></tr><tr><td>Hydroxide</td><td>amphoteric</td><td>basic</td><td>amphoteric</td><td>weakly basic</td><td>?</td><td>?</td></tr><tr><td>Oxide</td><td>amphoteric</td><td>strongly basic</td><td>amphoteric</td><td>mildly basic</td><td>mildly basic</td><td>?</td></tr></tbody></table> <h3>Compounds</h3> <p class="note">See also: <a href="/facts/Compounds_of_zinc/v22RgTRs">Compounds of zinc</a>, <a href="/facts/Organozinc_compounds/xpcLJCT4">Organozinc compounds</a>, <a href="/facts/Organocadmium_compound/0HbUyMzC">Organocadmium compound</a>, and <a href="/facts/Organomercury/MNDdMpEq">Organomercury</a></p> <p>All three metal ions form many <a href="/facts/Tetrahedral_molecular_geometry/583AL1sP">tetrahedral</a> species, such as MCl2−4. Both zinc and cadmium can also form octahedral complexes such as the <a href="/facts/Metal_ions_in_aqueous_solution/LtheVUDy">aqua ions</a> [M(H2O)6]2+ which are present in aqueous solutions of salts of these metals.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> Covalent character is achieved by using the s and p orbitals. Mercury, however, rarely exceeds a <a href="/facts/Coordination_number/mf48hsoX">coordination number</a> of four. Coordination numbers of 2, 3, 5, 7 and 8 are also known. </p> <h2 id="history">History</h2> <p>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 a <a href="/facts/Trivial_name/UWV8LfCB">trivial name</a>, but it has been called <i>group IIB</i> in the past. </p> <h3>Zinc</h3> <p>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.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a><a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> Zinc was distinctly recognized as a metal under the designation of <i>Fasada</i> in the medical Lexicon ascribed to the Hindu king Madanapala (of Taka dynasty) and written about the year 1374.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> The metal was also of use to <a href="/facts/Alchemy/CEx0U1Em">alchemists</a>.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> The name of the metal was first documented in the 16th century,<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a><a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> and is probably derived from the German <i>zinke</i> for the needle-like appearance of metallic crystals.<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> </p> <p>The isolation of metallic zinc in the West may have been achieved independently by several people in the 17th century.<a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a> German chemist <a href="/facts/Andreas_Sigismund_Marggraf/BtR4zHLt">Andreas Marggraf</a> is usually given credit for discovering pure metallic zinc in a 1746 experiment by heating a mixture of <a href="/facts/Calamine/vnqzNxCU">calamine</a> and charcoal in a closed vessel without copper to obtain a metal.<a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a> Experiments on frogs by the Italian doctor <a href="/facts/Luigi_Galvani/tvLUj9mn">Luigi Galvani</a> in 1780 with brass paved the way for the discovery of <a href="/facts/Battery_(electricity)/bqEpm4ue">electrical batteries</a>, galvanization and <a href="/facts/Cathodic_protection/6EjWvH1r">cathodic protection</a>.<a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a><a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a> In 1799, Galvani's friend, <a href="/facts/Alessandro_Volta/W9rIYxmv">Alessandro Volta</a>, invented the <a href="/facts/Voltaic_pile/9KoUfqGE">Voltaic pile</a>.<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a> The biological importance of zinc was not discovered until 1940 when <a href="/facts/Carbonic_anhydrase/je7bk6fk">carbonic anhydrase</a>, an enzyme that scrubs carbon dioxide from blood, was shown to have zinc in its <a href="/facts/Active_site/u9ua7rGu">active site</a>.<a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a> </p> <h3>Cadmium</h3> <p>In 1817, cadmium was discovered in Germany as an impurity in <a href="/facts/Zinc_carbonate/ffvou3Re">zinc carbonate</a> minerals (calamine) by <a href="/facts/Friedrich_Stromeyer/llcymrRj">Friedrich Stromeyer</a> and <a href="/facts/Karl_Samuel_Leberecht_Hermann/bcBFbgj6">Karl Samuel Leberecht Hermann</a>.<a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a> It was named after the Latin <i>cadmia</i> for "<a href="/facts/Calamine/vnqzNxCU">calamine</a>", a cadmium-bearing mixture of minerals, which was in turn named after the Greek mythological character, Κάδμος <a href="/facts/Cadmus/g75RkVLp">Cadmus</a>, the founder of <a href="/facts/Ancient_Thebes_(Boeotia)/PBN0g5la">Thebes</a>.<a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a> Stromeyer eventually isolated cadmium metal by <a href="/facts/Roasting_(metallurgy)/kvlzMoeg">roasting</a> and reduction of the <a href="/facts/Cadmium_sulfide/lsYV3Gum">sulfide</a>.<a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a><a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a><a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a> </p><p>In 1927, the <a href="/facts/Bureau_International_des_Poids_et_Mesures/tPEu4X0s">International Conference on Weights and Measures</a> redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths).<a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a> This definition has since been changed (see <a href="/facts/Krypton/llkNlCke">krypton</a>). At the same time, the <a href="/facts/International_Prototype_Meter/cR3xfvhn">International Prototype Meter</a> was used as standard for the length of a meter until 1960,<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a> when at the <a href="/facts/General_Conference_on_Weights_and_Measures/a1FPjTtr">General Conference on Weights and Measures</a> the meter was defined in terms of the orange-red <a href="/facts/Emission_line/HuI4Bj5f">emission line</a> in the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a> of the <a href="/facts/Krypton/llkNlCke">krypton</a>-86 atom in <a href="/facts/Vacuum/BTk3goyV">vacuum</a>.<a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a> </p> <h3>Mercury</h3> <p>Mercury has been found in Egyptian tombs which have been dated back to 1500 BC,<a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a> where mercury was used in cosmetics. It was also used by the ancient Chinese who believed it would improve and prolong health.<a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a> By 500 BC mercury was used to make <a href="/facts/Amalgam_(chemistry)/5dRXJyt3">amalgams</a> (Medieval Latin amalgama, "alloy of mercury") with other metals.<a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a> <a href="/facts/Alchemy/CEx0U1Em">Alchemists</a> thought of mercury as the <a href="/facts/Prima_materia/UjIpU5cg">First Matter</a> from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of <a href="/facts/Sulfur/IK0amTfM">sulfur</a> contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.<a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a> </p><p>Hg is the modern <a href="/facts/Chemical_symbol/2Fe1VAL0">chemical symbol</a> for mercury. It comes from <i>hydrargyrum</i>, a <a href="/facts/Latin/pM3Kge85">Latinized</a> form of the <a href="/facts/Greek_language/pzDd6eIz">Greek</a> word Ύδραργυρος (<i>hydrargyros</i>), 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 god <a href="/facts/Mercury_(mythology)/2omXHvrY">Mercury</a>, known for speed and mobility. It is associated with the planet <a href="/facts/Mercury_(planet)/lVa1GIyX">Mercury</a>; the astrological symbol for the planet is also one of the <a href="/facts/Alchemical_symbol/TIHkrNya">alchemical symbols</a> for the metal.<a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a> Mercury is the only metal for which the alchemical planetary name became the common name.<a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a> </p> <h3>Copernicium</h3> <p>The heaviest known group 12 element, copernicium, was <a href="/facts/Discovery_of_the_chemical_elements/QY4X2RP3">first created</a> on February 9, 1996, at the <a href="/facts/Gesellschaft_f%C3%BCr_Schwerionenforschung/KeCJHKP0">Gesellschaft für Schwerionenforschung</a> (GSI) in <a href="/facts/Darmstadt/UzVdfNVQ">Darmstadt</a>, Germany, by Sigurd Hofmann, <a href="/facts/Victor_Ninov/G9wpbGj9">Victor Ninov</a> et al.<a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a> It was then officially named by the <a href="/facts/International_Union_of_Pure_and_Applied_Chemistry/2AV6myCK">International Union of Pure and Applied Chemistry</a> (IUPAC) after <a href="/facts/Nicolaus_Copernicus/RvzhHNQR">Nicolaus Copernicus</a> on February 19, 2010, the 537th anniversary of Copernicus' birth.<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a> </p> <h2 id="occurrence">Occurrence</h2> <p>Like in most other <a href="/facts/D-block/BbzD5jUU">d-block</a> groups, the <a href="/facts/Abundance_of_elements_in_Earth%27s_crust/UDSVHH56">abundance in Earth's crust</a> of group 12 elements decreases with higher atomic number. Zinc is with 65 <a href="/facts/Parts_per_million/PozRuoLM">parts per million</a> (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.<a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a> Copernicium, as a synthetic element with a <a href="/facts/Half-life/kGVH8BAB">half-life</a> of a few minutes, may only be present in the laboratories where it was produced. </p> <p>Group 12 metals are <a href="/facts/Goldschmidt_classification/8p9CWrpe">chalcophiles</a>, meaning the elements have low affinities for <a href="/facts/Oxide/DXtoVe1C">oxides</a> and prefer to bond with <a href="/facts/Sulfide/d8YMjLeu">sulfides</a>. Chalcophiles formed as the crust solidified under the <a href="/facts/Redox/Pyd5RVcj">reducing</a> conditions of the early Earth's atmosphere.<a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a> The commercially most important minerals of group 12 elements are sulfide minerals.<a class="footnote-ref" id="fnref:88" href="#fn:88"><sup>88</sup></a> <a href="/facts/Sphalerite/5NumvnzR">Sphalerite</a>, which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains 60–62% zinc.<a class="footnote-ref" id="fnref:89" href="#fn:89"><sup>89</sup></a> No significant deposits of cadmium-containing ores are known. <a href="/facts/Greenockite/VCGfH1os">Greenockite</a> (CdS), the only cadmium <a href="/facts/Mineral/LkUFbNmv">mineral</a> 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, <a href="/facts/Lead/EYljasJN">lead</a> and <a href="/facts/Copper/I8PEE8oX">copper</a>.<a class="footnote-ref" id="fnref:90" href="#fn:90"><sup>90</sup></a><a class="footnote-ref" id="fnref:91" href="#fn:91"><sup>91</sup></a> One place where metallic cadmium can be found is the <a href="/facts/Vilyuy_River/nVYHzjGe">Vilyuy River</a> basin in <a href="/facts/Siberia/oaCoPEjF">Siberia</a>.<a class="footnote-ref" id="fnref:92" href="#fn:92"><sup>92</sup></a> Although mercury is an extremely rare element in the Earth's <a href="/facts/Crust_(geology)/FYG1kP4F">crust</a>,<a class="footnote-ref" id="fnref:93" href="#fn:93"><sup>93</sup></a> because it does not blend <a href="/facts/Geochemistry/05094gDu">geochemically</a> 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 in <a href="/facts/Cinnabar/MUzsHjFw">cinnabar</a> (HgS), <a href="/facts/Corderoite/dcl4dLFG">corderoite</a>, <a href="/facts/Livingstonite/RpjINsGQ">livingstonite</a> and other <a href="/facts/Mineral/LkUFbNmv">minerals</a>, with cinnabar being the most common ore.<a class="footnote-ref" id="fnref:94" href="#fn:94"><sup>94</sup></a> </p><p>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 billion <a href="/facts/Tonne/gMymLmWv">tonnes</a>.<a class="footnote-ref" id="fnref:95" href="#fn:95"><sup>95</sup></a> Large deposits are in Australia, Canada and the United States with the largest reserves in <a href="/facts/Iran/24yukge8">Iran</a>.<a class="footnote-ref" id="fnref:96" href="#fn:96"><sup>96</sup></a><a class="footnote-ref" id="fnref:97" href="#fn:97"><sup>97</sup></a><a class="footnote-ref" id="fnref:98" href="#fn:98"><sup>98</sup></a> At the current rate of consumption, these reserves are estimated to be depleted sometime between 2027 and 2055.<a class="footnote-ref" id="fnref:99" href="#fn:99"><sup>99</sup></a><a class="footnote-ref" id="fnref:100" href="#fn:100"><sup>100</sup></a> 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.<a class="footnote-ref" id="fnref:101" href="#fn:101"><sup>101</sup></a> In 2005, China was the top producer of mercury with almost two-thirds global share followed by <a href="/facts/Kyrgyzstan/MSNdCp8u">Kyrgyzstan</a>.<a class="footnote-ref" id="fnref:102" href="#fn:102"><sup>102</sup></a> Several other countries are believed to have unrecorded production of mercury from copper <a href="/facts/Electrowinning/XYkUqWVM">electrowinning</a> 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.<a class="footnote-ref" id="fnref:103" href="#fn:103"><sup>103</sup></a> </p> <h2 id="production">Production</h2> <p>Zinc is the fourth most common metal in use, trailing only <a href="/facts/Iron/QK1JYy8E">iron</a>, <a href="/facts/Aluminium/7wmR8jYE">aluminium</a>, and <a href="/facts/Copper/I8PEE8oX">copper</a> with an annual production of about 10 million tonnes.<a class="footnote-ref" id="fnref:104" href="#fn:104"><sup>104</sup></a> Worldwide, 95% of the zinc is mined from <a href="/facts/Sulfide/d8YMjLeu">sulfidic</a> ore deposits, in which sphalerite (ZnS) is nearly always mixed with the sulfides of copper, lead and iron. Zinc metal is produced using <a href="/facts/Extractive_metallurgy/TkszJ19Y">extractive metallurgy</a>.<a class="footnote-ref" id="fnref:105" href="#fn:105"><sup>105</sup></a> <a href="/facts/Roasting_(metallurgy)/kvlzMoeg">Roasting</a> converts the zinc sulfide concentrate produced during processing to zinc oxide.<a class="footnote-ref" id="fnref:106" href="#fn:106"><sup>106</sup></a> For further processing two basic methods are used: <a href="/facts/Pyrometallurgy/VuhDQhUj">pyrometallurgy</a> or <a href="/facts/Electrowinning/XYkUqWVM">electrowinning</a>. Pyrometallurgy processing reduces zinc oxide with <a href="/facts/Carbon/ukrgQexo">carbon</a> or <a href="/facts/Carbon_monoxide/CKuLtEMJ">carbon monoxide</a> at 950 °C (1,740 °F) into the metal, which is distilled as zinc vapor.<a class="footnote-ref" id="fnref:107" href="#fn:107"><sup>107</sup></a> The zinc vapor is collected in a condenser.<a class="footnote-ref" id="fnref:108" href="#fn:108"><sup>108</sup></a> Electrowinning processing leaches zinc from the ore concentrate by <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a>.<a class="footnote-ref" id="fnref:109" href="#fn:109"><sup>109</sup></a> After this step <a href="/facts/Electrolysis/pU75nCDI">electrolysis</a> is used to produce zinc metal.<a class="footnote-ref" id="fnref:110" href="#fn:110"><sup>110</sup></a> </p><p>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.<a class="footnote-ref" id="fnref:111" href="#fn:111"><sup>111</sup></a> Cadmium is isolated from the zinc produced from the flue dust by <a href="/facts/Vacuum_distillation/ep7NsYJ0">vacuum distillation</a> if the zinc is smelted, or cadmium sulfate is <a href="/facts/Precipitate/s3BgsLLY">precipitated</a> out of the electrolysis solution.<a class="footnote-ref" id="fnref:112" href="#fn:112"><sup>112</sup></a> </p><p>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.<a class="footnote-ref" id="fnref:113" href="#fn:113"><sup>113</sup></a> Mercury is extracted by heating cinnabar in a current of air and condensing the vapor.<a class="footnote-ref" id="fnref:114" href="#fn:114"><sup>114</sup></a> </p><p><a href="/facts/Superheavy_element/9PjYvCc3">Superheavy elements</a> such as copernicium are produced by bombarding lighter elements in <a href="/facts/Particle_accelerator/Pkuc08xC">particle accelerators</a> that induces <a href="/facts/Fusion_reaction/hP0gLDqj">fusion reactions</a>. 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 higher <a href="/facts/Atomic_number/bgAr581S">atomic numbers</a>.<a class="footnote-ref" id="fnref:115" href="#fn:115"><sup>115</sup></a> 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 by <a href="/facts/Victor_Ninov/G9wpbGj9">Victor Ninov</a>):<a class="footnote-ref" id="fnref:116" href="#fn:116"><sup>116</sup></a> </p> <a href="/facts/Lead-208/V9JFUTRo">20882Pb</a> + <a href="/facts/Zinc-70/4QJEMCzx">7030Zn</a> → 277112Cn + <a href="/facts/Neutron/oRCM1geb">n</a> <h2 id="applications">Applications</h2> <p>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 as <a href="/facts/Anti-corrosion/3PIHf1A8">anti-corrosion</a> (galvanization) agents<a class="footnote-ref" id="fnref:117" href="#fn:117"><sup>117</sup></a> as they will attract all local <a href="/facts/Oxidation/Pyd5RVcj">oxidation</a> until they completely corrode.[88] These protective coatings can be applied to other metals by <a href="/facts/Hot-dip_galvanizing/qWxshJAY">hot-dip galvanizing</a> a substance into the molten form of the metal,<a class="footnote-ref" id="fnref:118" href="#fn:118"><sup>118</sup></a> or through the process of <a href="/facts/Electroplating/HbKf0SBb">electroplating</a> which may be <a href="/facts/Passivation_(chemistry)/tPADJj5G">passivated</a> by the use of <a href="/facts/Monochromate/6xkFLIJw">chromate</a> salts.<a class="footnote-ref" id="fnref:119" href="#fn:119"><sup>119</sup></a> Group 12 elements are also used in <a href="/facts/Electrochemistry/C0RUWpBH">electrochemistry</a> as they may act as an alternative to the <a href="/facts/Standard_hydrogen_electrode/c6mksrr1">standard hydrogen electrode</a> in addition to being a secondary reference electrode.<a class="footnote-ref" id="fnref:120" href="#fn:120"><sup>120</sup></a> </p><p>In the US, zinc is used predominantly for <a href="/facts/Galvanization/htRtThFL">galvanizing</a> (55%) and for <a href="/facts/Brass/pe8EHk6x">brass</a>, <a href="/facts/Bronze/YCYCVIKt">bronze</a> and other alloys (37%).<a class="footnote-ref" id="fnref:121" href="#fn:121"><sup>121</sup></a> The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient <a href="/facts/Sacrificial_anode/lGBuszfA">sacrificial anode</a> in <a href="/facts/Cathodic_protection/6EjWvH1r">cathodic protection</a> (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe.<a class="footnote-ref" id="fnref:122" href="#fn:122"><sup>122</sup></a> Zinc acts as the <a href="/facts/Anode/TjYt95zG">anode</a> (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline.<a class="footnote-ref" id="fnref:123" href="#fn:123"><sup>123</sup></a><a class="footnote-ref" id="fnref:124" href="#fn:124"><sup>124</sup></a> Zinc is used to cathodically protect metals that are exposed to sea water from corrosion.<a class="footnote-ref" id="fnref:125" href="#fn:125"><sup>125</sup></a><a class="footnote-ref" id="fnref:126" href="#fn:126"><sup>126</sup></a> Zinc is used as an anode material for batteries such as in <a href="/facts/Zinc%E2%80%93carbon_battery/MDC00Uuh">zinc–carbon batteries</a><a class="footnote-ref" id="fnref:127" href="#fn:127"><sup>127</sup></a><a class="footnote-ref" id="fnref:128" href="#fn:128"><sup>128</sup></a> or <a href="/facts/Zinc%E2%80%93air_battery/khuroKtG">zinc–air battery</a>/fuel cells.<a class="footnote-ref" id="fnref:129" href="#fn:129"><sup>129</sup></a><a class="footnote-ref" id="fnref:130" href="#fn:130"><sup>130</sup></a><a class="footnote-ref" id="fnref:131" href="#fn:131"><sup>131</sup></a> 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.<a class="footnote-ref" id="fnref:132" href="#fn:132"><sup>132</sup></a> Brass is generally more <a href="/facts/Ductile/SBJsahEk">ductile</a> and stronger than copper and has superior <a href="/facts/Corrosion_resistance/lIC7H4we">corrosion resistance</a>.<a class="footnote-ref" id="fnref:133" href="#fn:133"><sup>133</sup></a> These properties make it useful in communication equipment, hardware, musical instruments, and water valves.<a class="footnote-ref" id="fnref:134" href="#fn:134"><sup>134</sup></a> Other widely used alloys that contain zinc include <a href="/facts/Nickel_silver/mXMKcugp">nickel silver</a>, typewriter metal, soft and aluminium <a href="/facts/Solder/GBvJH75t">solder</a>, and commercial <a href="/facts/Bronze/YCYCVIKt">bronze</a>.<a class="footnote-ref" id="fnref:135" href="#fn:135"><sup>135</sup></a> Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful in <a href="/facts/Die_casting/9bdIWfoe">die casting</a> as well as <a href="/facts/Spin_casting/HNyvaIbL">spin casting</a>, especially in the automotive, electrical, and hardware industries.<a class="footnote-ref" id="fnref:136" href="#fn:136"><sup>136</sup></a> These alloys are marketed under the name <a href="/facts/Zamak/lKC3PeXH">Zamak</a>.<a class="footnote-ref" id="fnref:137" href="#fn:137"><sup>137</sup></a> 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.<a class="footnote-ref" id="fnref:138" href="#fn:138"><sup>138</sup></a> </p><p>Cadmium has many common industrial uses as it is a key component in battery production, is present in <a href="/facts/Cadmium_pigments/3NeFypNH">cadmium pigments</a>,<a class="footnote-ref" id="fnref:139" href="#fn:139"><sup>139</sup></a> coatings,<a class="footnote-ref" id="fnref:140" href="#fn:140"><sup>140</sup></a> and is commonly used in electroplating.<a class="footnote-ref" id="fnref:141" href="#fn:141"><sup>141</sup></a> In 2009, 86% of cadmium was used in <a href="/facts/Battery_(electricity)/bqEpm4ue">batteries</a>, predominantly in <a href="/facts/Rechargeable_battery/A6zUkPkW">rechargeable</a> <a href="/facts/Nickel-cadmium_battery/JTbx4bcB">nickel-cadmium batteries</a>. 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%.<a class="footnote-ref" id="fnref:142" href="#fn:142"><sup>142</sup></a> Cadmium <a href="/facts/Electroplating/HbKf0SBb">electroplating</a>, consuming 6% of the global production, can be found in the aircraft industry due to the ability to resist <a href="/facts/Corrosion/lIC7H4we">corrosion</a> when applied to steel components.<a class="footnote-ref" id="fnref:143" href="#fn:143"><sup>143</sup></a> </p><p>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 in <a href="/facts/Fluorescent_lamps/R8SlXCyg">fluorescent lamps</a>,<a class="footnote-ref" id="fnref:144" href="#fn:144"><sup>144</sup></a> while most of the other applications are slowly phased out due to health and safety regulations,<a class="footnote-ref" id="fnref:145" href="#fn:145"><sup>145</sup></a> and is in some applications replaced with less toxic but considerably more expensive <a href="/facts/Galinstan/gJ6T8G8W">Galinstan</a> alloy.<a class="footnote-ref" id="fnref:146" href="#fn:146"><sup>146</sup></a> 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.<a class="footnote-ref" id="fnref:147" href="#fn:147"><sup>147</sup></a> It is still used as an ingredient in <a href="/facts/Amalgam_(dentistry)/1tJBCfwR">dental amalgams</a>. In the late 20th century the largest use of mercury<a class="footnote-ref" id="fnref:148" href="#fn:148"><sup>148</sup></a><a class="footnote-ref" id="fnref:149" href="#fn:149"><sup>149</sup></a> was in the mercury cell process (also called the <a href="/facts/Castner-Kellner_process/HBdE86Gy">Castner-Kellner process</a>) in the production of <a href="/facts/Chlorine/y27UwYBM">chlorine</a> and <a href="/facts/Caustic_soda/xjtdYtq7">caustic soda</a>.<a class="footnote-ref" id="fnref:150" href="#fn:150"><sup>150</sup></a> </p><p>Copernicium has no use other than research due to its very high radioactivity. </p> <h2 id="biological-role-and-toxicity">Biological role and toxicity</h2> <p>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. </p><p>Zinc is an essential <a href="/facts/Trace_element/fcIekKdo">trace element</a>, necessary for plants,<a class="footnote-ref" id="fnref:151" href="#fn:151"><sup>151</sup></a> animals,<a class="footnote-ref" id="fnref:152" href="#fn:152"><sup>152</sup></a> and <a href="/facts/Microorganism/pysJYcE2">microorganisms</a>.<a class="footnote-ref" id="fnref:153" href="#fn:153"><sup>153</sup></a> It is "typically the second most abundant transition metal in organisms" after <a href="/facts/Iron/QK1JYy8E">iron</a> and it is the only metal which appears in all <a href="/facts/Enzyme/DSI1Fh7y">enzyme classes</a>.<a class="footnote-ref" id="fnref:154" href="#fn:154"><sup>154</sup></a> There are 2–4 grams of zinc<a class="footnote-ref" id="fnref:155" href="#fn:155"><sup>155</sup></a> distributed throughout the human body,<a class="footnote-ref" id="fnref:156" href="#fn:156"><sup>156</sup></a> and it plays "ubiquitous biological roles".<a class="footnote-ref" id="fnref:157" href="#fn:157"><sup>157</sup></a> A 2006 study estimated that about 10% of human proteins (2800) potentially bind zinc, in addition to hundreds which transport and traffic zinc.<a class="footnote-ref" id="fnref:158" href="#fn:158"><sup>158</sup></a> In the U.S., the <a href="/facts/Recommended_Dietary_Allowance/FWaI93Dm">Recommended Dietary Allowance</a> (RDA) is 8 mg/day for women and 11 mg/day for men.<a class="footnote-ref" id="fnref:159" href="#fn:159"><sup>159</sup></a> Harmful excessive supplementation may be a problem and should probably not exceed 20 mg/day in healthy people,<a class="footnote-ref" id="fnref:160" href="#fn:160"><sup>160</sup></a> although the U.S. National Research Council set a Tolerable Upper Intake of 40 mg/day.<a class="footnote-ref" id="fnref:161" href="#fn:161"><sup>161</sup></a> </p><p>Mercury and cadmium are toxic and may cause environmental damage if they enter rivers or rain water. This may result in contaminated crops<a class="footnote-ref" id="fnref:162" href="#fn:162"><sup>162</sup></a> as well as the <a href="/facts/Bioaccumulation/KaHzFKnL">bioaccumulation</a> of mercury in a food chain leading to an increase in illnesses caused by <a href="/facts/Mercury_poisoning/xdSGkWLU">mercury</a> and <a href="/facts/Cadmium_poisoning/tKRPXnz6">cadmium poisoning</a>.<a class="footnote-ref" id="fnref:163" href="#fn:163"><sup>163</sup></a> </p> <h2 id="notes">Notes</h2> <h2 id="bibliography">Bibliography</h2> <ul><li>Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). <i>Advanced Inorganic Chemistry</i> (6th ed.). New York: John Wiley & Sons, Inc. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-471-19957-1.</li> <li>Emsley, John (2001). <a href="https://archive.org/details/naturesbuildingb0000emsl/page/499">"Zinc"</a>. <a href="https://archive.org/details/naturesbuildingb0000emsl"><i>Nature's Building Blocks: An A-Z Guide to the Elements</i></a>. Oxford, England, UK: Oxford University Press. pp. <a href="https://archive.org/details/naturesbuildingb0000emsl/page/499">499</a>–505. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-19-850340-8.</li> <li><a href="/facts/Norman_Greenwood/XRDmRE8L">Greenwood, Norman N.</a>; Earnshaw, Alan (1997). <i>Chemistry of the Elements</i> (2nd ed.). <a href="/facts/Butterworth-Heinemann/c9nUxIVF">Butterworth-Heinemann</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-08-037941-8.</li> <li>Lehto, R. S. (1968). "Zinc". In Clifford A. Hampel (ed.). <a href="https://archive.org/details/encyclopediaofch00hamp"><i>The Encyclopedia of the Chemical Elements</i></a>. New York: Reinhold Book Corporation. pp. <a href="https://archive.org/details/encyclopediaofch00hamp/page/822">822</a>–830. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-442-15598-8. <a href="/facts/LCCN_(identifier)/5hb5Cw2V">LCCN</a> <a href="https://lccn.loc.gov/68-29938">68-29938</a>.</li> <li>Stwertka, Albert (1998). "Zinc". <a href="https://archive.org/details/guidetoelements00stwe"><i>Guide to the Elements</i></a> (Revised ed.). Oxford University Press. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-19-508083-4.</li> <li><a href="/facts/Mary_Elvira_Weeks/eklpr8u4">Weeks, Mary Elvira</a> (1933). "III. Some Eighteenth-Century Metals". <i>The Discovery of the Elements</i>. Easton, PA: Journal of Chemical Education. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-7661-3872-8. {{cite book}}: ISBN / Date incompatibility (help)</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Fluck, E. (1988). "New Notations in the Periodic Table" (PDF). Pure Appl. Chem. 60 (3): 431–436. doi:10.1351/pac198860030431. S2CID 96704008. Retrieved 24 March 2012. <a href="http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf" target="_blank">http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Greenwood & Earnshaw 1997. - Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Cotton et al. 1999. - Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). Advanced Inorganic Chemistry (6th ed.). New York: John Wiley & Sons, Inc. ISBN 978-0-471-19957-1. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Housecroft, C. E.; Sharpe, A. G. (2008). Inorganic Chemistry (3rd ed.). Prentice Hall. ISBN 978-0-13-175553-6. <a href="978-0-13-175553-6" target="_blank">978-0-13-175553-6</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>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. PMID 17476264. S2CID 4347419. <a href="/wiki/Nature_(journal)" target="_blank">/wiki/Nature_(journal)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>The name volatile metals for group 12 has occasionally been used,[6] although this much more commonly refers to any metal having a high volatility. <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>340±10 K predicted, 357+112−108 K experimentally[7] <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Zinc Metal Properties". American Galvanizers Association. 2008. Archived from the original on February 21, 2009. Retrieved 2009-02-15. <a href="https://web.archive.org/web/20090221111748/http://galvanizeit.org/aga/designing-fabricating/design-considerations/zinc-metal-properties" target="_blank">https://web.archive.org/web/20090221111748/http://galvanizeit.org/aga/designing-fabricating/design-considerations/zinc-metal-properties</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>David R. Lide, ed. (2006). Handbook of Chemistry and Physics (87th ed.). Boca Raton, Florida: CRC Press, Taylor & Francis Group. p. 4-41. ISBN 978-0-8493-0487-3. <a href="978-0-8493-0487-3" target="_blank">978-0-8493-0487-3</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Heiserman, David L. (1992). "Element 30: Zinc". Exploring Chemical Elements and their Compounds. New York: TAB Books. p. 123. ISBN 978-0-8306-3018-9. <a href="978-0-8306-3018-9" target="_blank">978-0-8306-3018-9</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Ingalls, Walter Renton (1902). 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. The Engineering and Mining Journal. pp. 142–6. <a href="https://archive.org/details/productionandpr01ingagoog" target="_blank">https://archive.org/details/productionandpr01ingagoog</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Hammond, C. R The Elements in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press. ISBN 0-8493-0486-5. <a href="0-8493-0486-5" target="_blank">0-8493-0486-5</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Mewes, Jan-Michael; Smits, Odile R.; Kresse, Georg; Schwerdtfeger, Peter (2019). "Copernicium: A Relativistic Noble Liquid". Angewandte Chemie. 131 (50): 18132–18136. Bibcode:2019AngCh.13118132M. doi:10.1002/ange.201906966. ISSN 1521-3757. <a href="https://doi.org/10.1002%2Fange.201906966" target="_blank">https://doi.org/10.1002%2Fange.201906966</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Mewes, Jan-Michael; Smits, Odile R.; Kresse, Georg; Schwerdtfeger, Peter (2019). "Copernicium: A Relativistic Noble Liquid". Angewandte Chemie. 131 (50): 18132–18136. Bibcode:2019AngCh.13118132M. doi:10.1002/ange.201906966. 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