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
Wikipedia.
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News tagged with gold
Air-purifying church windows early nanotechnology
Nanotechnology / Nanomaterials
Aug 21, 2008 |
4.5 / 5 (58) |
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Stained glass windows that are painted with gold purify the air when they are lit up by sunlight, a team of Queensland University of Technology experts have discovered.
Scientists peel away the mystery behind gold's catalytic prowess
Sep 04, 2008 |
4.7 / 5 (35) |
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Few materials have exercised as much of a hold on the human imagination, or on human history, as has gold. But for all of its popular uses – money, medals, jewelry and more – gold's potential as a catalyst ...
Single-Molecule Magnets Open New Door for Information Technology
Mar 09, 2009 |
4.7 / 5 (24) |
2
(PhysOrg.com) -- Recent research by scientists in Italy and France shows that that single molecules have the ability to store information via their magnetic state. Their work is a first step toward a new generation ...
Nano sculptures in gold
Aug 01, 2008 |
4.1 / 5 (20) |
1
If someone is charged up, the colour of their face might change, but they don't immediately pull off one of their arms, only to reattach it as a third leg. With some molecules, however, the situation is quite ...
Study reveals principles behind stability and electronic properties of gold nanoclusters
Jul 14, 2008 |
4.5 / 5 (16) |
3
A report published in the July 8 issue of the journal Proceedings of the National Academy of Sciences (PNAS) is the first to describe the principles behind the stability and electronic properties of tiny nanoc ...
New method can capture catalysis, one molecule at a time
Nov 10, 2008 |
4.6 / 5 (14) |
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(PhysOrg.com) -- Cornell researchers have developed an ingenious microscopic method to observe the behavior of single nanoparticles of a catalyst, down to the resolution of single catalytic events.
Golden Nanorods for Medical Applications
Nanotechnology / Bio & Medicine
Sep 08, 2008 |
4.6 / 5 (14) |
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(PhysOrg.com) -- Gold nanoparticles are under consideration for a number of biomedical applications, such as tumor treatment. A German-American research team at Carnegie Mellon University in Pittsburgh, Hunter ...
Engineering new uses for gold
Aug 22, 2008 |
4.1 / 5 (15) |
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The glitter of gold may hold more than just beauty, or so says a team of MIT researchers that is working on ways to use tiny gold rods to fight cancer, deliver drugs and more.
Fresh pot of tea strikes anti-cancer gold
Nanotechnology / Bio & Medicine
Mar 24, 2009 |
5 / 5 (10) |
0
Researchers might one day brew up a cancer treatment in their afternoon cuppa, says a study in a Royal Society of Chemistry journal.
Purifying nanorods: Big success with tiny cleanup
Nanotechnology / Nanomaterials
Sep 22, 2008 |
4.4 / 5 (11) |
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Chemists at Rice University have discovered a novel method to produce ultra-pure gold nanorods -- tiny, wand-like nanoparticles that are being studied in dozens of labs worldwide for applications as broad as diagnosing disease ...
The gold standard: researchers use nanoparticles to make 3-D DNA nanotubes
Nanotechnology / Bio & Medicine
Jan 01, 2009 |
5 / 5 (8) |
0
Arizona State University researchers Hao Yan and Yan Liu imagine and assemble intricate structures on a scale almost unfathomably small. Their medium is the double-helical DNA molecule, a versatile building ...
Metal sheets with DNA framework may enable nanocircuits
Nanotechnology / Bio & Medicine
May 20, 2009 |
4.9 / 5 (8) |
1
(PhysOrg.com) -- Using DNA not as a genetic material but as a structural support, Cornell researchers have created thin sheets of gold nanoparticles held together by strands of DNA. The work could prove useful ...
Gold Nanostars Outshine the Competition
Oct 15, 2008 |
4.4 / 5 (8) |
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(PhysOrg.com) -- Novel nanoparticles being tested at the National Institute of Standards and Technology have researchers seeing stars. In a recent paper,* NIST scientists used surface-enhanced Raman spectroscopy ...
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 ...
Targeted nanospheres find, penetrate, then fuel burning of melanoma
Nanotechnology / Bio & Medicine
Feb 02, 2009 |
4.6 / 5 (7) |
1
Hollow gold nanospheres equipped with a targeting peptide find melanoma cells, penetrate them deeply, and then cook the tumor when bathed with near-infrared light, a research team led by scientists at The University of Texas ...
