Characteristics and Properties of Gold
- Gold is the most malleable of all metals.
- It can be drawn into a wire of single-atom width.
- Gold can be beaten into a sheet of 1 square meter.
- Gold leaf can be beaten thin enough to become semi-transparent.
- Gold is a good conductor of heat and electricity.
- Gold is slightly reddish-yellow in color.
- The color is determined by plasma oscillations among the metals valence electrons.
- Relativistic effects affect the orbitals around gold atoms, giving it a golden hue.
- Different alloys can produce colored gold, such as rose gold, white gold, green gold, blue gold, and purple gold.
- Colloidal gold appears red when particles are small and blue when particles are larger.
- Gold has only one stable isotope, 197Au.
- Thirty-six radioisotopes of gold have been synthesized.
- The most stable radioisotope is 195Au with a half-life of 186.1 days.
- Gold's radioisotopes decay through various processes such as proton emission, alpha decay, beta decay, and electron capture.
- Gold also has nuclear isomers, with 198m2Au being the most stable.
- Gold often occurs in free elemental form as nuggets or grains.
- It is found in rocks, veins, and alluvial deposits.
- Gold can form solid solutions with silver and be naturally alloyed with other metals like copper and palladium.
- Gold compounds can occur in minerals, often with tellurium.
- Gold is a relatively rare element.
- Gold has been used for coinage, jewelry, and art throughout history.
- It was once used as a monetary standard.
- Gold is used in electrical connectors, infrared shielding, colored glass production, gold leafing, and tooth restoration.
- Certain gold salts have medical applications as anti-inflammatories.
- China is the world's largest gold producer, followed by Russia and Australia.

Synthesis and Chemistry of Gold
- Gold has three decay paths: β decay, isomeric transition, and alpha decay.
- No other isomer or isotope of gold has three decay paths.
- The first synthesis of gold was conducted by Japanese physicist Hantaro Nagaoka in 1924 by neutron bombardment of mercury.
- An American team conducted the same experiment in 1941, achieving the same result and showing that the isotopes of gold produced were all radioactive.
- In 1980, Glenn Seaborg transmuted several thousand atoms of bismuth into gold.
- Gold can be manufactured in a nuclear reactor, but it is highly impractical and costly.
- Gold forms diverse compounds with oxidation states ranging from -1 to +5.
- Au(I) compounds are typically linear and commonly encountered in mining.
- Au(III) compounds have square planar structures and can form mixed-valence complexes.
- Gold does not react with oxygen or most acids, but can react with halogens and form gold sulfide.
- Gold readily dissolves in mercury at room temperature and forms alloys with other metals.
- Gold can exhibit oxidation states of -1, +2, and +5.
- Aurides, compounds containing the auride anion, can have gold in the -1 oxidation state.
- Gold(II) compounds are usually diamagnetic and form Au-Au bonds.
- Gold(II) sulfate contains Au4+2 cations, similar to the mercury(I) ion.
- Gold(V) is represented by gold pentafluoride, its derivative anion, and gold heptafluoride.

Occurrence of Gold
- Gold is thought to have been produced in supernova nucleosynthesis and from the collision of neutron stars.
- It is also believed to have been present in the dust from which the Solar System formed.
- Traditionally, gold in the universe is thought to have formed by the r-process in supernova nucleosynthesis.
- Recent studies suggest that gold and other heavy elements may also be produced in neutron star mergers.
- Spectroscopic signatures of gold and other heavy elements were observed in the GW170817 neutron star merger event.
- Gold in Earth's crust and mantle may have been delivered by asteroid impacts during the Late Heavy Bombardment.
- The asteroid that formed the Vredefort impact structure is associated with the richest gold deposits in the Witwatersrand basin.
- The gold-bearing Witwatersrand rocks were laid down before the Vredefort impact.
- The impact distorted the Witwatersrand basin, bringing the gold-bearing rocks to the surface.
- The discovery of the deposit in 1886 led to the Witwatersrand Gold Rush.
- Gold on Earth is thought to have been incorporated into the planet since its formation.
- Scientists found evidence of gold coming from the mantle at Deseado Massif in Argentina.
- Further research is needed for clarification.
- Gold is found in ores in rock formed from the Precambrian time onward.
- It often occurs as a native metal or in gold/silver alloys.
- Native gold is found in lode deposits or as free flakes, grains, or nuggets in alluvial deposits.
- Gold can occur with tellurium minerals and in rare alloys with copper, lead, and mercury.
- Microbes and earthquakes can also play a role in forming gold deposits.
- Gold is present in the world's oceans, but at very low concentrations.
- Gold concentrations in the Atlantic and Northeast Pacific are 50-150 femtomol/L.
- Mediterranean deep waters have slightly higher concentrations.
- Claims of economically recovering gold from seawater have been proven to be false.
- Previous data on gold concentrations in seawater were contaminated.

Historical Significance of Gold
- The oldest recorded gold artifacts date back to the late Paleolithic period, around 40,000 BC.
- The Varna Necropolis in Bulgaria contains the oldest well-dated gold artifacts, dating back to the 5th millennium BC.
- Gold artifacts also appeared in Ancient Egypt and Lower Mesopotam

Gold (Wikipedia)

This article is about the element. For other uses, see Gold (disambiguation).

"Element 79" redirects here. For the anthology, see Element 79 (anthology).

Gold is a chemical element with the symbol Au (from the Latin word aurum) and the atomic number 79. In its pure form, it is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second-lowest in the reactivity series. It is solid under standard conditions.

Gold, ₇₉Au

Gold
Appearance	Metallic yellow
Standard atomic weight Ar°(Au)
	196.966570±0.000004 196.97±0.01 (abridged)
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	group 11
Period	period 6
Block	d-block
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 (at 20° C)	19.283 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	−3, −2, −1, 0, +1, +2, +3, +5 (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 of gold
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc) (cF4)
Lattice constant	a = 407.86 pm (at 20 °C)
Thermal expansion	14.13×10−6/K (at 20 °C)
Thermal conductivity	318 W/(m⋅K)
Electrical resistivity	22.14 nΩ⋅m (at 20 °C)
Magnetic ordering	diamagnetic
Molar 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
Speed of sound thin rod	2030 m/s (at r.t.)
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 'gold'
Discovery	In the Middle East (before 6000 BCE)
Symbol	"Au": from Latin aurum
Isotopes of gold v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 195Au synth 186.01 d ε 195Pt 196Au synth 6.165 d β+ 196Pt β− 196Hg 197Au 100% stable 198Au synth 2.69464 d β− 198Hg 199Au synth 3.139 d β− 199Hg
Category: Gold view talk edit | references

Gold often occurs in free elemental (native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).

Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid alone, which dissolves silver and base metals, a property long used to refine gold and confirm the presence of gold in metallic substances, giving rise to the term 'acid test'. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. Gold also dissolves in mercury, forming amalgam alloys, and as the gold acts simply as a solute, this is not a chemical reaction.

A relatively rare element, gold is a precious metal that has been used for coinage, jewelry, and other works of art throughout recorded history. In the past, a gold standard was often implemented as a monetary policy. Gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after the Nixon shock measures of 1971.

In 2020, the world's largest gold producer was China, followed by Russia and Australia. As of 2020^[update], a total of around 201,296 tonnes of gold exist above ground. This is equal to a cube, with each side measuring roughly 21.7 meters (71 ft). The world's consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, as well as conductivity of electricity have led to its continued use in corrosion-resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, the production of colored glass, gold leafing, and tooth restoration. Certain gold salts are still used as anti-inflammatory agents in medicine.