a molecule (older also: Mol disgust) is a particle, which consists of at least two connected atoms, which are connected by kovalente connections. Molecules represent the smallest particles, which have the characteristics of the underlying material. It spends molecules,only one element are developed (O 2, N 2, P 4 u.v.m), most molecules are however connections from nonmetals with (or more) further nonmetals or metalloids. One calls a somewhat larger group of homogeneous atoms Cluster.

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the connected atoms

hold kind of connection together in molecules in molecules over common pairs of electrons. One calls such connections alsoAtomic bond, connection of pair of electrons or kovalente connection. Even if the individual atoms do not have full elementary charges, thus as ions to be present, it cannot come through asymmetrically distributed pairs of connection electrons to Teilladungen. One divides therefore the atomic bonds into:

  • kovalente connection/nonpolar atomic bond- Difference of the Elektronegativität of the connection partners is 0. This kind of the connection comes exactly taken only with element molecules, i.e. with molecules, which are together set only from an atomic kind, forwards. One seizes in the broader sense however also connections betweenAtoms (e.g. between C and H) as kovalente connections up, whose difference of the Elektronegativität is more largely 0 and smaller 0.4.
  • polar connection - difference of the Elektronegativität of the connection partners is more largely 0.4 and smaller 1,8.

intermediatemolecular forces (sortedafter removing strength)

between the molecules different forces can work, which for example on simmer themselves - and melting points and the solubility characteristics to affect can:


the structure of a molecule can in different kindsare described. The sum formula is e.g. suitable for simple molecules, in particular inorganic molecules. H 2 O for water or NH 3 for ammonia. It contains the atomic symbols in the molecule contained element places, of their number over an index (in deep positionNumber) is indicated.

Strukturformel der Ascorbinsäure
Structural formula of the ascorbic acid

the effect of inter+molecular forces depends even with smaller molecules on the spatial structure of the molecules. For the description the VSEPR theory serves this structure.

With more complex molecules, like it particularly in that to organic chemistry , supply a sum formula no sufficient description, there different molecules with the same sum formula (isomers) seem to often give can. Therefore for the structural formula is used which plots the structure.

In some cases, mirror-image built molecules,the Enantiomeren, also the structural formula gives not sufficiently to explanation about the outward effective structure. Here Fischer and Haworth projection are used.

With high-complex molecules such as proteins or polymere coal hydrates the spatial representation plays a still larger role.

Kalottenmodell für einige kleine Moleküle
Kalottenmodell forone tries some

small molecules to sketch Kalottenmodelle for molecules and to achieve spatial representations over colour. An example of a three-dimensional model of high-complicated bio molecules supplies the blood coloring material hemoglobin: One speaks then - depending upon level - of that Primary structure (defined with proteins by the succession of the amino acids), the secondary structure (unfolding to a Helix or a folding sheet), the Tertiary period structure (unfolding the secondary structure to balls or fibers) and the quart acre structure. (see for this: Protein)

see also:

Wiktionary: Molecule - word origin, synonyms and translations

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