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
Gene Testing In the Doctors Office
Nanotechnology / Bio & Medicine
Dec 02, 2009 |
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(PhysOrg.com) -- A portable instrument manufactured by Nanosphere Inc. and recently approved by the FDA, can detect genetic variations in blood that alter the effectiveness of some drugs.
Fast, easy, and highly sensitive arsenic detection with gold nanoparticles
Nanotechnology / Nanomaterials
Nov 25, 2009 |
5 / 5 (2) |
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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 ...
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Scientists create world's first molecular transistor
Dec 23, 2009 |
4.9 / 5 (23) |
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A group of scientists has succeeded in creating the first transistor made from a single molecule. The team, which includes researchers from Yale University and the Gwangju Institute of Science and Technology ...
Nanoscale changes in collagen are a tipoff to bone health
Dec 22, 2009 |
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Using a technique that provides detailed images of nanoscale structures, researchers at the University of Michigan and Detroit's Henry Ford Hospital have discovered changes in the collagen component of bone ...
Nanoparticles go platinum: NCEM instruments provide key images
Dec 21, 2009 |
4.7 / 5 (3) |
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At Berkeley Lab's National Center for Electron Microscopy it was revealed that single-stranded DNA can disperse bundles of single-walled carbon nanotubes into individual tubes and serve as guideposts for synthesizing ...
The next medical frontier: nano-surgery
Nanotechnology / Bio & Medicine
Dec 21, 2009 |
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(PhysOrg.com) -- Engineering professor's nanorobot could be performing non-invasive surgical procedures on patients with tumors within the next decade.
Silicon technology offers extended X-ray vision of high-energy cosmos
Space & Earth / Space Exploration
Dec 21, 2009 |
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(PhysOrg.com) -- As elements of the integrated circuits running our computers, phones and electronics, silicon wafers are everywhere. An ESA-led effort is establishing an out-of-this-world use for these ...
Many take dim view of new-fangled Christmas lights
Dec 21, 2009 |
1 / 5 (7) |
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(AP) -- To Steven Walls, it's beginning to look nothing like Christmas, anywhere he goes.
Researchers identify possible imaging method to stratify breast cancer without biopsy
Dec 17, 2009 |
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Scientists from the Kimmel Cancer Center at Jefferson have discovered a possible way for malignant breast tumors to be identified, without the need for a biopsy. The findings were published online ahead of print in the Journal of ...
Japan mines toxic e-waste for precious materials
Dec 17, 2009 |
4.9 / 5 (7) |
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Seeking to turn an environmental problem into an economic opportunity, high-tech companies in resource-poor Japan are mining mountains of toxic e-waste for precious materials.
New research may help to clean drainage from abandoned mines
Dec 16, 2009 |
4.8 / 5 (4) |
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(PhysOrg.com) -- In a quiet green glen near Ashville, Pa., lies a rust-colored pond. A deep, rectangular hole in the ground, it somewhat resembles an Olympic-sized pool. Few people, however, would make the ...
Growing Europe's nanowires
Dec 16, 2009 |
4.5 / 5 (2) |
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(PhysOrg.com) -- European researchers have developed state-of-the-art nanowire 'growing' technology, opening the way for faster, smaller microchips and creating a promising new avenue of research and industrial ...
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