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Molecule
hideA molecule is defined as a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules.
In the kinetic theory of gases the term molecule is often used for any gaseous particle regardless of its composition. According to this definition noble gas atoms are considered molecules despite the fact that they are composed of a single non-bonded atom.
A molecule may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules.
No typical molecule can be defined for ionic crystals (salts) and covalent crystals (network solids), although these are often composed of repeating unit cells that extend either in a plane (such as in graphene) or three-dimensionally (such as in diamond or sodium chloride). The theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding. In glasses (solids that exist in a vitreous disordered state), atoms may also be held together by chemical bonds without any definable molecule, but also without any of the regularity of repeating units that characterises crystals.
For more information about Molecule, read the full article at
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News tagged with molecules
BBS proteins shown to run an export business that protects cilia
Dec 28, 2009 |
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A protein complex mutated in human disease removes excess signaling molecules to prevent them from damaging cilia, say researchers from UMass Medical School. The study will be published in the December 28 ...
Faster, cheaper DNA sequencing method developed
Nanotechnology / Bio & Medicine
Dec 20, 2009 |
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(PhysOrg.com) -- Boston University biomedical engineers have devised a method for making future genome sequencing faster and cheaper by dramatically reducing the amount of DNA required, thus eliminating the ...
Tracing the traces: Nanogram concentrations of a toxic compound detected in chlorinated tap water
Chemistry / Analytical Chemistry
Dec 23, 2009 |
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(PhysOrg.com) -- Drinking water can transmit a number of diseases, including typhoid, dysentery, cholera, and diarrhea, which can then spread explosively throughout an entire service area. To avoid this problem, drinking ...
Caltech scientists film photons with electrons
Dec 16, 2009 |
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(PhysOrg.com) -- Techniques recently invented by researchers at the California Institute of Technology -- which allow the real-time, real-space visualization of fleeting changes in the structure of nanoscale ...
Using lasers to cool and manipulate molecules
Dec 07, 2009 |
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(PhysOrg.com) -- "For years, we have been using laser cooling to trap and manipulate atoms," David DeMille tells PhysOrg.com. "This has been very useful for both basic science and many applications. Recent ...
Scientists isolate new antifreeze molecule in Alaska beetle
Dec 14, 2009 |
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Scientists have identified a novel antifreeze molecule in a freeze-tolerant Alaska beetle able to survive temperatures below minus 100 degrees Fahrenheit. Unlike all previously described biological antifreezes that contain ...
Molecular freight: Synthetic nanoscale transport system modeled on nature
Dec 21, 2009 |
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(PhysOrg.com) -- Just like our roads, there is a lot of traffic within the cells in our bodies, because cell components, messenger molecules, and enzymes must also be brought to the right places in the cell. One of these ...
Making New Enzymes to Engineer Plants for Biofuel Production
Dec 21, 2009 |
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(PhysOrg.com) -- Brookhaven scientists have created a new enzyme with the potential to interfere with a key cell-wall component in plants, possibly leading to plants that are easier to "digest" and convert ...
Bourbon versus vodka: Bourbon hurts more the next day, performance is the same
Dec 18, 2009 |
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Many alcoholic beverages contain byproducts of the materials used in the fermenting process. These byproducts are called "congeners," complex organic molecules with toxic effects including acetone, acetaldehyde, fusel oil, ...
Heme channel found
Dec 17, 2009 |
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In some ways a cell in your body or an organelle in that cell is like an ancient walled town. Life inside either depends critically on the intelligence of the gatekeepers.
Scientists take theoretical research on 'nasty' molecule to next level
Dec 04, 2009 |
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(PhysOrg.com) -- Some atoms don't always follow the rules. Take the beryllium dimer, a seemingly simple molecule made up of two atoms that University of Delaware physicists Krzysztof Szalewicz and Konrad Patkowski ...
Innovation puts next-generation solar cells on the horizon
Dec 01, 2009 |
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In a world first, a Monash University-led international research team has developed an innovative way to boost the output of the next generation of solar cells.
Newly identified enzymes help plants sense elevated CO2 and could lead to water-wise crops
Dec 13, 2009 |
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Biologists have identified plant enzymes that may help to engineer plants that take advantage of elevated carbon dioxide to use water more efficiently. The finding could help to engineer crops that take advantage of rising ...
Newly explored bacteria reveal some huge RNA surprises
Dec 02, 2009 |
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(PhysOrg.com) -- Yale University researchers have found very large RNA structures within previously unstudied bacteria that appear crucial to basic biological functions such as helping viruses infect cells ...
Machine Converts CO2 into Gasoline, Diesel, and Jet Fuel
Nov 23, 2009 |
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(PhysOrg.com) -- Researchers at Sandia National Laboratories have built a machine that uses the sun's energy to convert carbon dioxide waste from power plants into transportation fuels such as gasoline, diesel, ...
