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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
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 ...
Buffer gas cooling could open up the field of ultracold physics
Sep 17, 2009 |
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(PhysOrg.com) -- "Scientists have been making Bose-Einstein Condensates [BECs] for nearly 15 years," Charlie Doret tells PhysOrg.com. "Essentially all BEC research to date, however, begins with laser cooling. Unfortunately, ...
Scientists Fabricate Organic Transistor with Improved Performance
Apr 24, 2009 |
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(PhysOrg.com) -- Organic semiconductors are promising building blocks for many devices, from LEDs to transistors, offering potential advantages such as cost-effectiveness, flexibility, and high performance. ...
Faster, cheaper DNA sequencing method developed
Nanotechnology / Bio & Medicine
Dec 20, 2009 |
4.4 / 5 (24) |
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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 ...
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 ...
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 ...
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 ...
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 ...
Innovation puts next-generation solar cells on the horizon
Dec 01, 2009 |
4.3 / 5 (30) |
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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.
Machine Converts CO2 into Gasoline, Diesel, and Jet Fuel
Nov 23, 2009 |
4.4 / 5 (45) |
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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, ...
Two-In-One Punch Knocks Out Drug Resistant Cancer Cells
Nanotechnology / Bio & Medicine
Nov 04, 2009 |
5 / 5 (4) |
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(PhysOrg.com) -- Cancer cells, like bacteria, can develop resistance to drug therapy, leading to relapse of disease. One approach showing promise in overcoming multidrug resistance in tumors is to combine two different anticancer ...
A Mars Rover Named 'Curiosity'
Space & Earth / Space Exploration
Oct 30, 2009 |
4.9 / 5 (18) |
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(PhysOrg.com) -- If you found your grandmother's diary, tattered and dust covered, up in the attic, would you read it? Of course you would. Granny was a pistol! Brush off the dust, open up the little book, ...
Magnetic nanotags spot cancer in mice earlier than methods now in clinical use
Nanotechnology / Bio & Medicine
Oct 13, 2009 |
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Searching for biomarkers that can warn of diseases such as cancer while they are still in their earliest stage is likely to become far easier thanks to an innovative biosensor chip developed by Stanford University ...
Researchers create molecular diode
Oct 13, 2009 |
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Recently, at Arizona State University's Biodesign Institute, N.J. Tao and collaborators have found a way to make a key electrical component on a phenomenally tiny scale. Their single-molecule diode is described ...
Team reports major step forward in cell reprogramming
Oct 08, 2009 |
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(PhysOrg.com) -- A team of Harvard Stem Cell Institute (HSCI) researchers has made a major advance toward producing induced pluripotent stem cells, or iPS cells, that are safe enough to use in treating diseases ...
