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 Chemical series 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?O·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 220 ?GPa Poisson ratio 0.44 Mohs hardness 2.5 Vickers hardness 216 ?MPa Brinell hardness  ? 2450 ?MPa CAS registry number 7440-57-5 Selected isotopes Main article: Isotopes of gold iso NA half-life DM DE (MeV) DP 195Au syn 186.10 d e 0.227 195Pt 196Au syn 6.183 d e 1.506 196Pt ß- 0.686 196Hg 197Au 100% 197Au is stable with 118 neutrons 198Au syn 2.69517 d ß- 1.372 198Hg 199Au syn 3.169 d ß- 0.453 199Hg References Gold (pronounced /'go?ld/) is a chemical element with the symbol Au (from the Latin aurum, meaning shining dawn) and atomic number 79. It is a highly sought-after precious metal which, for many centuries, has been used as money, a store of value and in jewelry. The metal occurs as nuggets or grains in rocks, underground "veins" and in alluvial deposits. It is one of the coinage metals. Gold is dense, soft, shiny and the most malleable and ductile of the known metals. Pure gold has a bright yellow color traditionally considered attractive. Gold formed the basis for the gold standard used before the collapse of the Bretton Woods system. 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. Gold does not react with most chemicals, but is attacked by chlorine, fluorine, aqua regia and cyanide. 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 this 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.