Element Gold

Gold ElementIt is a chemical element with the symbol Au (from Latin: aurum) and atomic number 79, making it one of the higher atomic number elements that occur naturally.
In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions.
Gold often occurs in free elemental (native) form, as nuggets or grains, in rocks, in veins, and in alluvial deposits.
Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold also dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys, but this is not a chemical reaction.

Names and Identifiers

Chemical Formula:Au
CAS:7740-57-5
Molecular Weight:196.967 g/mol
EC Number :231-165-9
MDL Number:MFCD00003436
Color:golden yellow
Other Names:Or, Oro, Ouro, Guld
PubChem CID:23985
IUPAC Name:Gold
Inchl:InChI=1S/Au
InChI Key:PCHJSUWPFVWCPO-UHFFFAOYSA-N
Canonical SMILES:[Au]
ICSC Number:n/a

Physical & Chemical Properties

Phase:Solid
Density:19.30 g/cm³
Boiling Point:3243 K ​(2970 °C, ​5378 °F)
Melting Point:1337.33 K ​(1064.18 °C, ​1947.52 °F)
Molecular Formula:Au
Flash Point:4 °C
Exact Mass:196.966507
Symbol:n/a
Signal Word:n/a
Hazard Statements:n/a
Precautionary Statements:n/a
Hazard Codes:Xi,Xn,F
Risk Phrases:R36/38
Safety Phrases:S26-S36/37/39-S45-S62-S36/37
RIDADR:UN 1789 8/PG 3
WGK Germany:3
RTECS:MD5420000
Packaging Group:II
Hazard Class:6.1

Gold has only one stable isotope, 197 Au, which is also its only naturally occurring isotope, so gold is both a mononuclidic and monoisotopic element.
Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205. The most stable of these is 195Au with a half-life of 186.1 days.

Naturally occurring isotopes

IsotopeMass/DaNatural abundance (atom %)Nuclear spin (I)Magnetic moment (μ/μN)
197Au196.966543 (4)1003/20.148159

Radiosotope data

IsotopeMass/DaHalf-lifeMode of decayNuclear spinNuclear magnetic moment
194Au193.965341.64 dEC to 194Pt10.075
195Au194.965017186.12 dEC to 195Pt3/20.149
196Au196.9665516.18 dEC to 196Pt; β to 196Hg20.591
198Au197.9682252.694 dβ to 198Hg20.5934
199Au198.9687483.14 dβ to 199Hg3/20.2715

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