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 synthesised. - 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