Decent Look

This article is about the metal. For the color, see Gold (color). For other uses, see Gold (disambiguation).
79 platinum ← gold → mercury
Ag
↑
Au
↓
Rg Periodic Table - Extended Periodic Table


General
Name, Symbol, Number gold, Au, 79
Element category transition metals
Group, Period, Block 11, 6, d
Appearance metallic yellow

Standard atomic weight 196.966569(4)  g·mol−1
Electron configuration [Xe] 4f14 5d10 6s1
Electrons per shell 2, 8, 18, 32, 18, 1
Physical properties
Phase solid
Density (near r.t.) 19.3  g·cm−3
Liquid density at m.p. 17.31  g·cm−3
Melting point 1337.33 K
(1064.18 °C, 1947.52 °F)
Boiling point 3129 K
(2856 °C, 5173 °F)
Heat of fusion 12.55  kJ·mol−1
Heat of vaporization 324  kJ·mol−1
Specific heat capacity (25 °C) 25.418  J·mol−1·K−1
Vapor pressure P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1646 1814 2021 2281 2620 3078

Atomic properties
Crystal structure cubic face centered
Oxidation states −1, 1, 2, 3, 4, 5
(amphoteric oxide)
Electronegativity 2.54 (Pauling scale)
Ionization energies 1st: 890.1 kJ/mol
2nd: 1980 kJ/mol
Atomic radius 135  pm
Atomic radius (calc.) 174  pm
Covalent radius 144  pm
Van der Waals radius 166 pm
Miscellaneous
Magnetic ordering diamagnetic
Electrical resistivity (20 °C) 22.14 n Ω·m
Thermal conductivity (300 K) 318  W·m−1·K−1
Thermal expansion (25 °C) 14.2  µm·m−1·K−1
Speed of sound (thin rod) (r.t.) (hard-drawn)
2030  m·s−1
Young's modulus 78  GPa
Tensile strain 0.00157  
Shear modulus 27  GPa
Bulk modulus 180  GPa
Poisson ratio 0.44
Mohs hardness 2.5
Vickers hardness 216  MPa
Brinell hardness ? 2450  MPa
CAS registry number 7440-57-5
Most-stable isotopes
Main article: Isotopes of gold iso NA half-life DM DE (MeV) DP
195Au syn 186.10 d ε 0.227 195Pt
196Au syn 6.183 d ε 1.506 196Pt
β- 0.686 196Hg
197Au 100% 197Au is stable with 118 neutrons
198Au syn 2.69517 d β- 1.372 198Hg
199Au syn 3.169 d β- 0.453 199Hg

References

Gold (pronounced /ˈɡoʊld/) is a chemical element with the symbol Au (Latin: aurum) and an atomic number of 79. It is a highly sought-after precious metal in jewelry, in sculpture, and for ornamentation since the beginning of recorded history. The metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Gold is dense, soft, shiny and the most malleable and ductile pure metal known. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without rusting in air or water. It is one of the coinage metals and formed the basis for the gold standard used before the collapse of the Bretton Woods system in 1971.

At the end of 2006, it was estimated that all the gold ever mined totaled 158,000 tonnes. [1] This can be represented by a cube with an edge length of just 20.2 meters. Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion. Chemically, gold is a transition metal and can form trivalent and univalent cations upon solvation. At STP it is attacked by aqua regia (a mixture of acids), forming chloroauric acid and by alkaline solutions of cyanide but not by single acids such as hydrochloric, nitric or sulfuric acids. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Since gold is insoluble in nitric acid which will dissolve silver and base metals, this is exploited as the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the colloquial term "acid test", referring to a gold standard test for genuine value.