Gold
hideGold (pronounced /ˈɡoʊld/) is a chemical element with the symbol Au (Latin: aurum) and an atomic number of 79. It has been a highly sought-after precious metal 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 and luster traditionally considered attractive, which it maintains without oxidizing in air or water. 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.
At the end of 2006, it was estimated that all the gold ever mined totaled 158,000 tonnes. This can be represented by a cube with an edge length of just 20.2 meters. Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion and excellent quality as a conductor of electricity. Chemically, gold is a transition metal and can form trivalent and univalent cations upon solvation. At STP it is attacked by aqua regia (a mixture of acids), forming chloroauric acid and by alkaline solutions of cyanide but not by single acids such as hydrochloric, nitric or sulfuric acids. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Since gold is insoluble in nitric acid which will dissolve silver and base metals, this is exploited as 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.
For more information about Gold, read the full article at
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News tagged with gold
Fast, easy, and highly sensitive arsenic detection with gold nanoparticles
Nanotechnology / Nanomaterials
Nov 25, 2009 |
5 / 5 (1) |
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(PhysOrg.com) -- Mention of arsenic poisoning usually brings to mind underhanded murder. However, the danger of arsenic poisoning from contaminated drinking water is far greater. Low concentrations of arsenic are found in ...
Highlight: Damping of acoustic vibrations in gold nanoparticles
Nov 19, 2009 |
4 / 5 (2) |
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Vibrations in nanostructures offer applications in molecular-scale biological sensing and ultrasensitive mass detection. To approach single-atom sensing, it is necessary to reduce the dimensions of the structures ...
Danish nanowires have great potential
Nov 02, 2009 |
3 / 5 (1) |
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Danish nanophysicists have developed a new method for manufacturing the cornerstone of nanotechnology research - nanowires. The discovery has great potential for the development of nanoelectronics and highly ...
Gold Nanoparticles Delivery Platinum Warheads to Tumors
Nanotechnology / Bio & Medicine
Oct 29, 2009 |
4.9 / 5 (7) |
2
(PhysOrg.com) -- Cisplatin is one of the most powerful and effective drugs for treating a wide variety of cancers, but serious side effects ultimately limit the drug's use and effectiveness. Now, however, researchers have ...
Dark matter sleuths to design world's largest WIMP catcher
Oct 29, 2009 |
4 / 5 (6) |
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A team of researchers led by a Case Western Reserve University physicist is planning the world's largest, most sensitive experiment to catch the stuff of dark matter, stuff that's proved way beyond invisible.
Smallest nanoantennas for high-speed data networks
Oct 20, 2009 |
3.3 / 5 (3) |
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More than 120 years after the discovery of the electromagnetic character of radio waves by Heinrich Hertz, wireless data transmission dominates information technology. Higher and higher radio frequencies are ...
New nanotech sensor developed with medical, chemistry applications
Nanotechnology / Bio & Medicine
Oct 13, 2009 |
5 / 5 (1) |
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Researchers at Oregon State University and other institutions have developed a new "plasmonic nanorod metamaterial" using extraordinarily tiny rods of gold that will have important applications in medical, biological and ...
Graphene Used As Floating-Molecular Carpet To Ornament It With 24-Carat Gold 'Snowflakes'
Nanotechnology / Nanomaterials
Oct 12, 2009 |
4.2 / 5 (6) |
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(PhysOrg.com) -- In an effort to make graphene more useful in electronics applications, Kansas State University engineers made a golden discovery -- gold "snowflakes" on graphene.
Bacterium helps formation of gold
Oct 07, 2009 |
4 / 5 (8) |
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Australian scientists have found that the bacterium Cupriavidus metallidurans catalyses the biomineralisation of gold by transforming toxic gold compounds to their metallic form using active cellular mechan ...
All That Glitters Is Now Gold
Oct 01, 2009 |
3.4 / 5 (5) |
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(PhysOrg.com) -- In full sunlight at mid-day, gold objects are brilliant and richly colored. Put those same objects in a dark interior room with only fluorescent lamps, however, and they will look pale and ...
Oxygen in place of chlorine: Towards a more environmentally friendly propylene oxide synthesis
Nanotechnology / Nanomaterials
Oct 01, 2009 |
4.8 / 5 (4) |
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(PhysOrg.com) -- Propylene oxide is an important bulk chemical that is used primarily in the production of polyurethane plastics. Currently, propylene oxide is usually made from propylene (propene) in a process that uses ...
Harnessing nanopatterns: Tiny textures can produce big differences
Nanotechnology / Nanomaterials
Sep 24, 2009 |
5 / 5 (4) |
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(PhysOrg.com) -- Research at MIT has uncovered new information about how nanoscale patterns on the surface of a material can produce significant changes in the way it interacts with liquids. The discovery ...
Gold solution for enhancing nanocrystal electrical conductance
Nanotechnology / Nanomaterials
Sep 10, 2009 |
5 / 5 (3) |
1
In a development that holds much promise for the future of solar cells made from nanocrystals, and the use of solar energy to produce clean and renewable liquid transportation fuels, researchers with the U.S. ...
Award for turning wool into gold
Nanotechnology / Nanomaterials
Aug 31, 2009 |
3 / 5 (8) |
9
A Victoria University (New Zealand) scientist has won a prestigious innovation award for turning pure New Zealand Merino wool into gold.
Platinum nanocatalyst could aid drugmakers
Nanotechnology / Bio & Medicine
Aug 31, 2009 |
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(PhysOrg.com) -- Nanoparticles combining platinum and gold act as superefficient catalysts, but chemists have struggled to create them in an industrially useful form. Rice University chemists have answered the call this week ...
