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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
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 ...
Faster, cheaper DNA sequencing method developed
Nanotechnology / Bio & Medicine
Dec 20, 2009 |
4.4 / 5 (25) |
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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 ...
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 ...
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 ...
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Scientists create world's first molecular transistor
Dec 23, 2009 |
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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 ...
Mystery solved: Scientists now know how smallpox kills
Dec 22, 2009 |
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A team of researchers working in a high containment laboratory at the Centers for Disease Control and Prevention in Atlanta, GA, have solved a fundamental mystery about smallpox that has puzzled scientists long after the ...
Researchers are on the path to creating nano-MRI images
Dec 22, 2009 |
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(PhysOrg.com) -- Cornell researchers are devising methods to detect the magnetic fields of individual electrons and atomic nuclei, which they hope to use to make a nanoscale version of magnetic resonance imaging.
Switchable Nanostructures Made with DNA
Nanotechnology / Bio & Medicine
Dec 21, 2009 |
4.6 / 5 (9) |
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(PhysOrg.com) -- Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have found a new way to use a synthetic form of DNA to control the assembly of nanoparticles — this time resulting ...
Naturally occurring lipid blocks RSV infection in lungs
Dec 21, 2009 |
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Researchers at National Jewish Health have discovered that a naturally occurring lipid in the lung can prevent RSV infection and inhibit spread of the virus after an infection is established. RSV is the major cause of hospitalization ...
A novel gene found for childhood-onset asthma
Dec 23, 2009 |
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Pediatric researchers have identified a novel gene involved in childhood asthma, in one of the largest gene studies to date of the common respiratory disease. Because the gene, called DENND1B, affects cells and signaling ...
Proline Repeats in Protein Help Grow Tooth Enamel (w/ Podcast)
Dec 21, 2009 |
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(PhysOrg.com) -- A simple amino acid that is repeated in the center of proteins found in tooth enamel makes teeth stronger and more resilient, according to new research at the University of Illinois at Chicago.
New insight in nerve cell communication
Medicine & Health / Neuroscience
Dec 22, 2009 |
4 / 5 (1) |
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Communication between nerve cells is vital for our bodies to function. Part of this communication happens through vesicles containing signalling molecules called neurotransmitters. The vesicle fuses with the ...
Gene therapy makes mice breath easier
Dec 21, 2009 |
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Researchers from Boston University School of Medicine (BUSM) have discovered a new gene therapy that may prevent the progression of emphysema. The study, which appears on-line in the Journal of Clinical Investigation, descri ...
Protein that represses genes may play role in cell growth
Dec 21, 2009 |
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(PhysOrg.com) -- A Cornell study shows the protein not only activates some genes involved in the regulation of cell growth and signaling, but also may play a role in preventing cancers by inhibiting cell proliferation.
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