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
Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
- New videos show RNA as it's never been seenon January 15, 2021 at 4:00 pm
A new Northwestern University-led study is unfolding the mystery of how RNA molecules fold themselves to fit inside cells and perform specific functions. The findings could potentially break down a barrier to understanding and developing treatments for RNA-related diseases, including spinal muscular atrophy and perhaps even the novel coronavirus.
- Changes in nutrient storage and metabolism help...on January 15, 2021 at 2:23 pm
RIKEN developmental biologists have analyzed the transitions that precede metamorphosis in fruit fly larvae using experiments and mathematical modeling1. They have also identified the survival strategies underlying these transitions. While conducted on fruit flies, their study may have relevance for other species, including humans.
- Fluorescence microscopy at highest spatial and...on January 15, 2021 at 2:04 pm
LMU researchers simplify the MINFLUX microscope and have succeeded in differentiating molecules that are extremely close together and tracking their dynamics.
- Intimate associations between SARS-CoV-2 and...on January 15, 2021 at 1:30 pm
As one wise pundit recently observed, "everybody is a virologist now." For the many people whose interest in biology formerly began and ended with "the mitochondria is the powerhouse of the cell," a second axiom can now be offered, namely, that the virus is the thief of power. In other words, what the mitochondria giveth, the virus taketh away.
- Research breaks new ground in understanding how a...on January 14, 2021 at 9:32 pm
A team of biophysicists from the University of Massachusetts Amherst and Penn State College of Medicine set out to tackle the long-standing question about the nature of force generation by myosin, the molecular motor responsible for muscle contraction and many other cellular processes. The key question they addressed—one of the most controversial topics in the field—was: how does myosin convert chemical energy, in the form of ATP, into mechanical work?