WebElements

Periodic Table

gold

Atomic number: 79
Atomic weight: 196.96655
Symbol: Au
Group number: 11
Electronic configuration: [Xe].4f14.5d10.6s1

Description

Gold is usually alloyed in jewellery to give it more strength, and the term carat describes the amount of gold present (24 carats is pure gold). It is estimated that all the gold in the world, so far refined, could be placed in a single cube 60 ft. on a side. It is metallic, with a yellow colour when in a mass, but when finely divided it may be black, ruby, or purple. It is the most malleable and ductile metal; 1 ounce (28 g) of gold can be beaten out to 300 square feet. It is a soft metal and is usually alloyed to give it more strength. It is a good conductor of heat and electricity, and is unaffected by air and most reagents.

The most common gold compounds are auric chloride (AuCl3) and chlorauric acid (HAuCl4). A mixture of one part nitric acid with three of hydrochloric acid is called aqua regia (because it dissolved gold, the King of Metals). It is unaffected by air and most reagents. It is found free in nature and associated with quartz, pyrite and other minerals. Two thirds of the world's supply comes from South Africa, and 2/3 of USA production is from South Dakota and Nevada. Gold is found in sea water, but no effective economic process has been designed (yet) to extract it from this source.

General information

Discoveror: Known since ancient times.
Date discovered:
Discovered at: not known
Meaning of name: From the Anglo-Saxon word "gold" (the origin of the symbol Au is the Latin word "aurum" meaning "gold")

Physical data

Standard state: solid at 298 K
Colour: gold
Density of solid at ambient temperature/kg m-3: 19300
Molar volume/cm3: 10.21

Radii /pm

Atomic: 174
Covalent (single bond):
Pauling radius for the ion [Au]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius156.0no data63.519.7

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 2.54
Allred Rochow: 1.41

Crystal Structure

structure: ccp (cubic close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

ball-and-stick.gif

Temperatures (/K)

melting point: 1337.33
boiling point: 3129

Enthalpies /kJ mol-1

fusion: 12.5
vaporization: 324

single bond enthalpies:
Au-F Au-Cl Au-Br Au-I Au-Au
no data no data no data no data 221.3

Ionization enthalpies /kJ mol-1

Number Enthalpy
1st890
2nd1980

Isotopes

This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
197Au196.966543 (4)100

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Au.html