gold

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

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 (R_max)

orbital	s	p	d	f
radius	156.0	no data	63.5	19.7

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.

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
1st	890
2nd	1980

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
197Au	196.966543 (4)	100

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW