Affinity (chemistry)
Affinity (from the Latin affinitas = relationship - it was previously believed that substances that react with one another must have a kind of relationship to one another) is the driving force of a chemical reaction , namely the effort of ions, atoms or groups of atoms to enter into a ( covalent ) bond ( Reaction affinity ). If two metal ions compete for oxygen, one speaks of oxygen affinity . If, on the other hand, a bond is based solely on the electrostatic attraction of the binding partners, one speaks of binding affinity .
The so-called affinity chromatography uses this type of interaction between possible binding partners for the purpose of purification : a chemically stable pseudo-substrate (non-convertible, mostly small molecule) is bound to a carrier and serves to connect the binding partner (e.g. a protein ), the one has a high affinity for this, to hold back and thus free from impurities.
The affinity series of oxygen e.g. B. reads: Au <Pt <Ag <Hg <Cu <Sn <Pb <Fe <C <Al <Mg <Ca <Na <K.
See also
Individual evidence
- ^ Entry on affinity. In: Römpp Online . Georg Thieme Verlag, accessed on June 14, 2014.