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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A novel cellular process to engulf nano-sized...
on August 16, 2019 at 10:31 pm
Nanometers are one billionth of a meter, a metric typically used to measure molecules and scientific building blocks not visible to the human eye. Materials of tens and/or several hundred nanometers in diameter have unique properties, and thus have been widely used in diagnosing and treating various human diseases. One major challenge to use these nano-sized materials is how to deliver them into cells and reach their sites of action.
Organic dye in zinc oxide interlayer stabilizes...
on August 16, 2019 at 1:13 pm
Organic solar cells are made of cheap and abundant materials, but their efficiency and stability still lag behind those of silicon-based solar cells. A Chinese-German team of scientists has found a way to enhance the electric conductivity of organic solar cells, which increases their performances. Doping the metal oxide interlayer, which connected the electrode and active layer, with a modified organic dye boosted both the efficiency and stability, the study published in the journal Angewandte […]
Ring-shaped multi-carbon compound cyclocarbon...
on August 16, 2019 at 12:40 pm
A team of researchers from Oxford University and IBM Research has for the first time successfully synthesized the ring-shaped multi-carbon compound cyclocarbon. In their paper published in the journal Science, the group describes the process they used and what they learned about the bonds that hold a cyclocarbon together.
Discovery provides path to pathogen-targeted...
on August 16, 2019 at 10:58 am
"Take with food" is a common warning for people using antibiotics, but a discovery announced this week in the scientific journal Nature may create a path to more targeted drugs.
Catalytic transformation of ethylene
on August 16, 2019 at 10:56 am
National University of Singapore chemists have developed a catalytic method using visible light for the difunctionalization of ethylene for potential use in the production of fine chemicals.