These are organized by a classification scheme developed exclusively for Cosma. More…
molecule : the smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms — Webster
Molecule is an electrically neutral group of two or more atoms held together by chemical bonds. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with oxygen (O2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (H2O). Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are generally not considered single molecules.
Molecules as components of matter are common in organic substances (and therefore biochemistry). They also make up most of the oceans and atmosphere. However, the majority of familiar solid substances on Earth, including most of the minerals that make up the crust, mantle, and core of the Earth, contain many chemical bonds, but are not made of identifiable molecules. Also, 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, quartz, or sodium chloride). The theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding, which means that solid metals are also not made of molecules. In glasses (solids that exist in a vitreous disordered state), atoms may also be held together by chemical bonds with no presence of any definable molecule, nor any of the regularity of repeating units that characterizes crystals. — Wikipedia
Molecular physics is the study of the physical properties of molecules, the chemical bonds between atoms as well as the molecular dynamics. Its most important experimental techniques are the various types of spectroscopy; scattering is also used. The field is closely related to atomic physics and overlaps greatly with theoretical chemistry, physical chemistry and chemical physics.
In addition to the electronic excitation states which are known from atoms, molecules exhibit rotational and vibrational modes whose energy levels are quantized. The smallest energy differences exist between different rotational states: pure rotational spectra are in the far infrared region (about 30 – 150 µm wavelength) of the electromagnetic spectrum. Vibrational spectra are in the near infrared (about 1 – 5 µm) and spectra resulting from electronic transitions are mostly in the visible and ultraviolet regions. From measuring rotational and vibrational spectra properties of molecules like the distance between the nuclei can be specifically calculated.
One important aspect of molecular physics is that the essential atomic orbital theory in the field of atomic physics expands to the molecular orbital theory. — Wikipedia
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Bird genes are multitaskers, say scientists
on September 25, 2020 at 9:00 pm
Scientists from the University of Sheffield have found that although male and female birds have an almost identical set of genes, they function differently in each sex through a mechanism called alternative splicing.
Researchers help develop sustainable polymers
on September 25, 2020 at 7:19 pm
Researchers at the FAMU-FSU College of Engineering have made new discoveries on the effects of temperature on sustainable polymers. Their findings may help the industry to produce plastics that are better for the environment.
Back to Venus: Upstart company wants to beat NASA...
on September 25, 2020 at 5:58 pm
Can a small American aerospace company get to Venus before NASA returns to our superheated planetary neighbor?
Antiferromagnet lattice arrangements influence...
on September 25, 2020 at 5:34 pm
Antiferromagnets contain orderly lattices of atoms and molecules, whose magnetic moments are always pointed in exactly opposite directions to those of their neighbors. These materials are driven to transition to other, more disorderly quantum states of matter, or 'phases,' by the quantum fluctuations of their atoms and molecules—but so far, the precise nature of this process hasn't been fully explored. Through new research published in EPJ B, Yoshihiro Nishiyama at Okayama University in Japan […]
New method allows precise gene control by light
on September 25, 2020 at 5:21 pm
A novel optical switch makes it possible to precisely control the lifespan of genetic copies. These are used by the cell as building instructions for the production of proteins. The method was developed by researchers from the universities of Bonn and Bayreuth. It may significantly advance the investigation of dynamic processes in living cells. The study is published in the journal Nature Communications.