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New techniques reveal properties of solid-state chiral materials

Chiral molecules—that is, those that have mirror images of themselves—have significant benefits for transistors and solar energy devices. Studying their properties in close detail, though, has been tricky due to the limited ...

How E. coli defends itself against antibiotics

Imagine that you have a very sore throat. You're sick, your throat hurts, and a visit to the doctor confirms that the pain is due to a bacterial infection. You get a prescription for antibiotics, which quickly sorts out your ...

'Two-for-one' fission aims to improve solar cell efficiency

Singlet fission occurs when an organic molecule absorbs one photon of light, then splits that light's energy in two—a doubling effect that has the potential to improve the light-harvesting efficiency in solar cells, assuming ...

An alternative way to manipulate quantum states

Researchers at ETH Zurich have shown that quantum states of single electron spins can be controlled by currents of electrons whose spins are evenly aligned. In the future, this method could be used in electronic circuit elements.

Transforming inexpensive quinolines into complex drug candidates

An innovative synthesis strategy has opened the way to 2D/3D fused frameworks using inexpensive quinolines as feedstock, report scientists from Tokyo Tech. By leveraging a light-sensitive borate intermediate, the scientists ...

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Molecule

A 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.

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