Cosma / Communication / Knowledge / Realm / Physical / Matter / Molecule




molecule : the smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms — Webster

OneLook, Free Dictionary, Wiktionary


Roget’s II (, Merriam-Webster Thesaurus, Visuwords


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

Encyclopædia Britannica


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

App: Molecules (Theodore Gray)

Merck Index Online – Chemicals, Drugs and Biologicals (Royal Society of Chemistry)
Merck Index (Wikipedia)




WorldCat, Library of Congress, UPenn Online Books, Open Library




MathMol: An introductory site for Molecular Modeling (NYU)


Molecular Physics Group (Institute Of Physics)
Molecular Structure Center: Indiana University


Science News,, NPR Archives









More News … - latest science and technology news stories internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • Novel zeolites-silver catalyst boosts...
    on May 13, 2022 at 3:08 pm

    A research group led by Prof. Xiao Jianping and Assoc. Prof. Jiao Feng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. Qu Zhenping from Dalian University of Technology, designed a tandem bifunctional zeolites-silver (Ag) catalyst that could boost formaldehyde oxidation at low temperatures.

  • Chemists synthesize psychotropic compound from...
    on May 13, 2022 at 11:04 am

    The bark of the Galbulimima belgraveana tree, found only in remote rainforests of Papua New Guinea and northern Australia, has long been used by indigenous people for both healing and ceremony. A tea brewed from the bark not only induces a dreamlike state but is said to ease pain and fever. To probe these effects, researchers have isolated more than 40 unique chemicals from the tree bark but have struggled to reproduce the compounds in the lab or study their biology.

  • A gene in tuberculosis bacteria is found...
    on May 12, 2022 at 9:35 pm

    Lei Zhang, Ph.D., and Michael Niederweis, Ph.D., of the University of Alabama at Birmingham have made what they call "a major step" in understanding how Mycobacterium tuberculosis acquires iron from its human host—a process essential for the pathogenesis of this bacterium. Tuberculosis kills more than 1 million people each year, but without iron, M. tuberculosis cannot grow.

  • Bacteria with recording function capture gut...
    on May 12, 2022 at 6:00 pm

    Researchers from ETH Zurich, University Hospital of Bern and the University of Bern have equipped gut bacteria with data logger functionality as a way of monitoring which genes are active in the bacteria. These microorganisms could one day offer a noninvasive means of diagnosing disease or assessing the impact of a diet on health.

  • The future of desalination? A fast, efficient,...
    on May 12, 2022 at 6:00 pm

    Water scarcity is a growing problem around the world. Desalination of seawater is an established method to produce drinkable water but comes with huge energy costs. For the first time, researchers use fluorine-based nanostructures to successfully filter salt from water. Compared to current desalination methods, these fluorous nanochannels work faster, require less pressure and less energy, and are a more effective filter.


Here are links to pages about closely related subjects.

Knowledge Realm


Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid


1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.