Gold jewellery

Gold,  ₇₉Au

General properties
Pronunciation	/ˈɡoʊld/ GOHLD
Appearance	metallic yellow
Standard atomic weight (Ar, std)	7002196966569000000♠196.966569(5)
Gold in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Ag ↑ Au ↓ Rg platinum ← gold → mercury
Atomic number (Z)	79
Group, period	group 11, period 6
Block	d-block
Element category	transition metal
Electron configuration	[Xe] 4f14 5d10 6s1
Electrons per shell	2, 8, 18, 32, 18, 1
Physical properties
Phase (at STP)	solid
Melting point	1337.33 K ​(1064.18 °C, ​1947.52 °F)
Boiling point	3243 K ​(2970 °C, ​5378 °F)
Density (near r.t.)	19.30 g/cm3
when liquid (at m.p.)	17.31 g/cm3
Heat of fusion	12.55 kJ/mol
Heat of vaporization	342 kJ/mol
Molar heat capacity	25.418 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1646 1814 2021 2281 2620 3078
Atomic properties
Oxidation states	5, 3, 2, 1, −1, −2, −3 ​(an amphoteric oxide)
Electronegativity	Pauling scale: 2.54
Ionization energies	1st: 890.1 kJ/mol 2nd: 1980 kJ/mol
Atomic radius	empirical: 144 pm
Covalent radius	136±6 pm
Van der Waals radius	166 pm
Spectral lines
Miscellanea
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	2030 m/s (at r.t.)
Thermal expansion	14.2 µm/(m·K) (at 25 °C)
Thermal conductivity	318 W/(m·K)
Electrical resistivity	22.14 nΩ·m (at 20 °C)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−28.0·10−6 cm3/mol (at 296 K)
Tensile strength	120 MPa
Young's modulus	79 GPa
Shear modulus	27 GPa
Bulk modulus	180 GPa
Poisson ratio	0.4
Mohs hardness	2.5
Vickers hardness	188–216 MPa
Brinell hardness	188–245 MPa
CAS Number	7440-57-5
History
Naming	from Latin aurum, meaning gold
Discovery	In the Middle East (before 6000 BCE)
Main isotopes of gold
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 195Au syn 186.10 d ε 195Pt 196Au syn 6.183 d ε 196Pt β− 196Hg 197Au 100% stable 198Au syn 2.69517 d β− 198Hg 199Au syn 3.169 d β− 199Hg
| references |

Spectral lines

Gold is a chemical element with symbol Au (from Latin: aurum) and atomic number 79. In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental (native) form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum) and also naturally alloyed with copper and palladium. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).

Gold is thought to have been produced in supernova nucleosynthesis, from the collision of neutron stars, and to have been present in the dust from which the Solar System formed. Because the Earth was molten when it was formed, almost all of the gold present in the early Earth probably sank into the planetary core. Therefore, most of the gold that is in the Earth's crust and mantle is thought to have been delivered to Earth later, by asteroid impacts during the Late Heavy Bombardment, about 4 billion years ago.