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Chemical Element
Gold is a chemical element with symbol Au and atomic number 79. In its purest form, it is a bright,
and a group 11 element.

compounds, often with tellurium (gold tellurides).
the collision of two neutron stars[4] and to have been present in the dust from which theSolar
Gold resists attacks by individual acids, but it can be dissolved by aqua regia (nitro-hydrochloric
acid, literally "royal water"). The acid mixture causes the formation of a soluble gold
tetrachloride anion. Gold metal also dissolves in alkaline solutions of cyanide, which are used
property that has long been used to refinegold and to confirm the presence of gold in items,
giving rise to the term acid test; it dissolves in mercury, though, forming amalgam alloys, but this
is not a chemical reaction.
other arts since long before the beginning ofrecorded history. In the past, a gold standard was
minted as a circulating currency in the 1930s, and the world gold standard was finally abandoned
easy handling and minting, easy smelting, corrosion resistance, distinct color, and non-reactivity
to other elements.


Although gold is the most noble of the noble metals,[15][16] it still forms many diverse compounds.
The oxidation state of gold in its compounds ranges from 1 to +5, but Au(I) and Au(III) dominate
soft ligandssuch as thioethers, thiolates, and tertiary phosphines. Au(I) compounds are typically
Au(I) derivatives.[17]
atom centers in Au(III) complexes, like other d8compounds, are typically square planar,
with chemical bonds that have both covalent and ionic character.
Gold is unaffected by oxygen at any temperature[clarification needed][citation needed]; similarly, it does not react
with ozone[citation needed]. Gold is strongly attacked by fluorine at dull-red heat [18][19] to form gold(III)
Some free halogens react with gold.[20] Powdered gold reacts with chlorine at 180 C to
form AuCl3.[21] Gold reacts with bromine at 140 C to formgold(III) bromide, but reacts only very
slowly with iodine to form the monoiodide.
Gold does not react with sulfur directly,[22] but gold(III) sulfide can be made by passing hydrogen
Gold is unaffected by most acids. It does not react