Editing Silver (section)

==Chemistry==
{| class="wikitable" style="float:right; clear:right; margin-left:1em; margin-top:0;"
|+ Oxidation states and stereochemistries of silver<ref name="Greenwood and Earnshaw-7" />
|-
! Oxidation <br />state !! Coordination <br />number !! Stereochemistry !! Representative<br />compound
|-
| 0 (d<sup>10</sup>s<sup>1</sup>) || 3 || Planar || Ag(CO)<sub>3</sub>
|-
| rowspan="4" | 1 (d<sup>10</sup>) || 2 || Linear || [Ag(CN)<sub>2</sub>]<sup>−</sup>
|-
| 3 || Trigonal planar || AgI(PEt<sub>2</sub>Ar)<sub>2</sub>
|-
| 4 || Tetrahedral || [Ag(diars)<sub>2</sub>]<sup>+</sup>
|-
| 6 || Octahedral || AgF, AgCl, AgBr
|-
| 2 (d<sup>9</sup>) || 4 || Square planar || [Ag(py)<sub>4</sub>]<sup>2+</sup>
|-
| rowspan="2" | 3 (d<sup>8</sup>) || 4 || Square planar || [AgF<sub>4</sub>]<sup>−</sup>
|-
| 6 || Octahedral || [AgF<sub>6</sub>]<sup>3−</sup>
|}
Silver is a rather unreactive metal. This is because its filled 4d shell is not very effective in shielding the electrostatic forces of attraction from the nucleus to the outermost 5s electron, and hence silver is near the bottom of the [[electrochemical series]] (''E''<sup>0</sup>(Ag<sup>+</sup>/Ag) = +0.799&nbsp;V).<ref name="Greenwood and Earnshaw-5" /> In group 11, silver has the lowest first ionisation energy (showing the instability of the 5s orbital), but has higher second and third ionisation energies than copper and gold (showing the stability of the 4d orbitals), so that the chemistry of silver is predominantly that of the +1 oxidation state, reflecting the increasingly limited range of oxidation states along the transition series as the d-orbitals fill and stabilise.<ref name="Greenwood and Earnshaw-8">Greenwood and Earnshaw, p. 1180</ref> Unlike [[copper]], for which the larger [[hydration energy]] of Cu<sup>2+</sup> as compared to Cu<sup>+</sup> is the reason why the former is the more stable in aqueous solution and solids despite lacking the stable filled d-subshell of the latter, with silver this effect is swamped by its larger second ionisation energy. Hence, Ag<sup>+</sup> is the stable species in aqueous solution and solids, with Ag<sup>2+</sup> being much less stable as it oxidises water.<ref name="Greenwood and Earnshaw-8" />

Most silver compounds have significant [[covalent bond|covalent]] character due to the small size and high first ionisation energy (730.8&nbsp;kJ/mol) of silver.<ref name="Greenwood and Earnshaw-5" /> Furthermore, silver's Pauling [[electronegativity]] of 1.93 is higher than that of [[lead]] (1.87), and its [[electron affinity]] of 125.6&nbsp;kJ/mol is much higher than that of [[hydrogen]] (72.8&nbsp;kJ/mol) and not much less than that of [[oxygen]] (141.0&nbsp;kJ/mol).<ref name="Greenwood and Earnshaw-4">Greenwood and Earnshaw, p. 1176</ref> Due to its full d-subshell, silver in its main +1 oxidation state exhibits relatively few properties of the transition metals proper from groups 4 to 10, forming rather unstable [[organometallic compound]]s, forming linear complexes showing very low [[coordination number]]s like 2, and forming an amphoteric oxide<ref>Lidin RA 1996, ''Inorganic substances handbook'', Begell House, New York, {{ISBN|1-56700-065-7}}. p. 5</ref> as well as [[Zintl phase]]s like the [[post-transition metal]]s.<ref>Goodwin F, Guruswamy S, Kainer KU, Kammer C, Knabl W, Koethe A, Leichtfreid G, Schlamp G, Stickler R & Warlimont H 2005, 'Noble metals and noble metal alloys', in ''Springer Handbook of Condensed Matter and Materials Data,'' W Martienssen & H Warlimont (eds), Springer, Berlin, pp.&nbsp;329–406, {{ISBN|3-540-44376-2}}. p. 341</ref> Unlike the preceding transition metals, the +1 oxidation state of silver is stable even in the absence of [[pi backbonding|π-acceptor ligands]].<ref name="Greenwood and Earnshaw-8" />

Silver does not react with air, even at red heat, and thus was considered by [[alchemist]]s as a [[noble metal]], along with gold. Its reactivity is intermediate between that of copper (which forms [[copper(I) oxide]] when heated in air to red heat) and gold. Like copper, silver reacts with [[sulfur]] and its compounds; in their presence, silver tarnishes in air to form the black [[silver sulfide]] (copper forms the green [[sulfate]] instead, while gold does not react). While silver is not attacked by non-oxidising acids, the metal dissolves readily in hot concentrated [[sulfuric acid]], as well as dilute or concentrated [[nitric acid]]. In the presence of air, and especially in the presence of [[hydrogen peroxide]], silver dissolves readily in aqueous solutions of [[cyanide]].<ref name="Greenwood and Earnshaw-7">Greenwood and Earnshaw, p. 1179</ref>

The three main forms of deterioration in historical silver artifacts are tarnishing, formation of [[silver chloride]] due to long-term immersion in salt water, as well as reaction with [[nitrate]] ions or oxygen. Fresh silver chloride is pale yellow, becoming purplish on exposure to light; it projects slightly from the surface of the artifact or coin. The precipitation of copper in ancient silver can be used to date artifacts, as copper is nearly always a constituent of silver alloys.<ref>[https://web.archive.org/web/20130509014548/http://events.nace.org/library/corrosion/Artifacts/silver.asp "Silver Artifacts"] in ''Corrosion – Artifacts''. NACE Resource Center</ref>

Silver metal is attacked by strong [[Oxidizing agent|oxidant]] such as [[potassium permanganate]] ({{chem|KMnO|4}}) and [[potassium dichromate]] ({{chem|K|2|Cr|2|O|7}}), and in the presence of [[potassium bromide]] ({{chem|KBr}}). These compounds are used in photography to [[bleach]] silver images, converting them to silver bromide that can either be fixed with [[thiosulfate]] or redeveloped to [[potassium dichromate#photography|intensify]] the original image. Silver forms [[cyanide]] complexes ([[silver cyanide]]) that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in [[electroplating]] of silver.<ref name="Bjelkhagen-1995">{{cite book| pages = [https://archive.org/details/silverhalidereco00bjel/page/n172 156]–66| title=Silver-halide recording materials: for holography and their processing| url = https://archive.org/details/silverhalidereco00bjel| url-access = limited| last = Bjelkhagen |first=Hans I.| publisher= Springer| date =1995| isbn = 978-3-540-58619-7}}</ref>

The common [[oxidation state]]s of silver are (in order of commonness): +1 (the most stable state; for example, [[silver nitrate]], AgNO<sub>3</sub>); +2 (highly oxidising; for example, [[silver(II) fluoride]], AgF<sub>2</sub>); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF<sub>4</sub>).<ref>{{cite journal |last1=Riedel |first1=Sebastian |last2=Kaupp |first2=Martin |date=2009 |title=The highest oxidation states of the transition metal elements |journal=Coordination Chemistry Reviews |volume=253 |issue=5–6 |doi=10.1016/j.ccr.2008.07.014|pages=606–24}}</ref> The +3 state requires very strong oxidising agents to attain, such as [[fluorine]] or [[peroxodisulfate]], and some silver(III) compounds react with atmospheric moisture and attack glass.<ref name="Greenwood and Earnshaw-12">Greenwood and Earnshaw, p. 1188</ref> Indeed, silver(III) fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidising agent, [[krypton difluoride]].<ref name="Greenwood and Earnshaw-1">Greenwood and Earnshaw, p. 903</ref>