Molecule

A molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. The science of molecules is called molecular chemistry or molecular physics, depending on the particular aspect of focus. Molecular chemistry is concerned with the laws governing the interaction between molecules that results in the formation and breakage of chemical bonds, while molecular physics is concerned with the laws governing their structure and properties. In practice, however, this distinction is rather vague.

Related Topics:
Particle - Chemical substance - Chemical composition - Chemistry - Molecular physics - Chemical bond

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

According to the strict definition, molecules can consist of one atom (as in noble gases) or more atoms bonded together. The concept of monatomic (single-atom) molecule is used almost exclusively in the kinetic theory of gases. In molecular sciences a molecule consists of a stable system (bound state) comprising two or more atoms. The term unstable molecule is used for very reactive species, i.e. short-lived assemblies (resonances) of electrons and nuclei, such as radicals, molecular ions, Rydberg molecules (see Rydberg atoms), transition states, Van der Waals complexes, or systems of colliding atoms as in Bose-Einstein condensates. A peculiar use of the term molecular is as a synonym to covalent, which arises from the fact that, unlike covalent compounds, ionic compounds do not yield well-defined smallest particles that would be consistent with the definition above.

Related Topics:
Atom - Noble gas - Monatomic - Kinetic theory - Bound state - Reactive - Resonance - Electron - Nuclei - Radicals - Ion - Rydberg molecule - Rydberg atom - Transition state - Van der Waals complex - Bose-Einstein condensate - Covalent - Ionic compound

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Although the concept of molecule was first introduced in 1811 by Avogadro, the existence of molecules was still an open debate in the chemistry community until the work of Perrin (1911). The modern theory of molecules makes great use of the many numerical techniques offered by computational chemistry.

Related Topics:
1811 - Avogadro - Perrin - 1911 - Computational chemistry

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

For a list of molecules see the List of compounds.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~