Electronics & Semiconductors

Marrying models with experiments to build more efficient solar cells

In a single day, enough sunlight strikes Earth to power the world for an entire year—that is, if we can find a way to capture that energy cheaply and efficiently. While the cost of solar energy has decreased dramatically, ...

Engineering

Automation speeds the search for stable proteins

Harnessing the power of robotics and machine intelligence, researchers from Princeton Engineering and Rutgers University have found a way to design stable proteins in a fraction of the time of current state of the art. The ...

Energy & Green Tech

How Canada's oilsands can help build better roads

The future seems bleak for Canada's oilsands. But given the world's ongoing need for smooth, safe roads, there is hope for the industry. Asphalt binder made from oilsands bitumen is the ideal glue to hold the world's 40 million ...

Engineering

One step closer to fire-safe, recyclable lithium-metal batteries

To power our increasingly electrified society, energy storage technology must evolve and adapt to meet the growing demand. Lithium-ion batteries, already essential to myriad technology, will require dramatic improvements ...

Electronics & Semiconductors

Logical switching using one single molecule

Logic gates, the basic elements of the digital world, can now be built using one single molecule. An example is XOR, with two inputs. If at least one of them is "1," then the output is "1," as well; otherwise, it is 0. These ...

Engineering

With a whiff, 'e-nose' can sense fine whiskey

Scotch or Irish, single malt or blended? While a whiskey enthusiast might be able to distinguish the good stuff from run-of-the-mill by smell alone, most tipplers rely on the label, black or otherwise.

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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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