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 gmol1
Electron configuration	Xe 4f14 5d10 6s1
Electrons per shell	2 8 18 32 18 1
Physical properties
Phase	solid
Density	19.3 gcm3
Liquid density at m.p.	17.31 gcm3
Melting point	1337.33 K
Boiling point	3129 K
Heat of fusion	12.55 kJmol1
Heat of vaporization	324 kJmol1
Specific heat capacity	25.418 Jmol1K1
Vapor pressure P 1 10 100 1 k 10 k 100 k at T 1646 1814 2021 2281 2620 3078
Atomic properties
Crystal structure	cubic face centered
Oxidation states	1 1 2 3 4 5
Electronegativity	2.54
Ionization energies	1st: 890.1 kJ/mol
	2nd: 1980 kJ/mol
Atomic radius	135 pm
Atomic radius	174 pm
Covalent radius	144 pm
Van der Waals radius	166 pm
Miscellaneous
Magnetic ordering	diamagnetic
Electrical resistivity	22.14 nm
Thermal conductivity	318 Wm1K1
Thermal expansion	14.2 mm1K1
Speed of sound	2030 ms1
Youngs 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 DP 195Au syn 186.10 d 0.227 195 Pt 196Au syn 6.183 d 1.506 196 Pt - 0.686 196 Hg 197Au 100% 197Au is stable with 118 neutrons 198Au syn 2.69517 d - 1.372 198 Hg 199Au syn 3.169 d - 0.453 199 Hg
References

Gold is a chemical element with the symbol Au and atomic number 79. It is a highly sought-after precious metal having been used as money as a store of value 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 traditionally considered attractive. 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. The ISO currency code of gold bullion is XAU.

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 forming chloroauric acid and by alkaline solutions of cyanide but not by hydrochloric nitric or sulphuric acids. Gold dissolves in mercury forming amalgam alloys but does not react with it. Gold is insoluble in nitric acid which will dissolve silver and base metals and is 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.