Neuroscience

Astrocytes identified as master 'conductors' of the brain

In the orchestra of the brain, the firing of each neuron is controlled by two notes—excitatory and inhibitory—that come from two distinct forms of a cellular structure called synapses. Synapses are essentially the connections ...

Immunology

New study points to a better way to ward off asthma triggers

Every day, ten Americans die from asthma. While quick-acting inhalers and medications can reduce inflammation during an asthma attack, people with asthma have few tools to prevent the next attack from coming.

Medical research

RNA structures of coronavirus reveal potential drug targets

The SARS-CoV-2 coronavirus RNA genome structure was studied in detail by researchers from the University of Groningen, the International Institute of Molecular and Cell Biology in Warsaw, and Leiden University. The RNA structures ...

Neuroscience

Surprising insights into the role of autophagy in neuron

It appears that autophagy protects neurons in the brain, but for different reasons than previously assumed, as researchers from the Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Charité in Berlin have ...

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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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