Medications

More efficient drug development with the help of computer models

The coronavirus has the world in its grip. Finding a cure has never been more important. Unfortunately, the development of new drugs for treatment of the COVID-19 disease caused by the virus and development of a vaccine are ...

Genetics

Study identifies group of genes with altered expression in autism

Autism has long been associated only with behavioral and environmental factors, but the role of genetics in its development is now increasingly evident. Some 100 genes have been found to play a role in autism spectrum disorder, ...

Medical research

A study reveals potential causes of female infertility

Over the last six years a group of Estonian geneticists led by Associate Professor Agne Velthut-Meikas and Ph.D. student Ilmatar Rooda from the TalTech Department of Chemistry and Biotechnology have studied genes previously ...

Medical research

Pomace olive oil reduces obesity

Researchers from the Department of Pharmacology, Paediatrics and Radiology at the University of Seville, in collaboration with Dr. Rodriguez from the International University of Catalonia, have confirmed that orujo (pomace) ...

Medical research

Study identifies potential drug treatments for telomere diseases

Capping decades of research, a new study may offer a breakthrough in treating dyskeratosis congenita and other so-called telomere diseases, in which cells age prematurely. Using cells donated by patients with the disease, ...

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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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