In chemistry, chemical affinity is the force of attraction (or affinity) between atoms that keeps them in combination in a molecule as well as the force of attraction between molecules, such as those of biological significance. [1] The atoms of a given element, for example, may have a greater affinity for the atoms of one element than for another, e.g. hydrogen H has a great affinity for chlorine Cl, with which it easily and rapidly combines to form hydrogen chloride, but has little or no affinity for argon. The affinity between an enzyme and a substrate molecule is another example.

Human attraction
A very complex example is the affinity between two people (human molecules), such as was outlined in German polymath Johann von Goethe's 1809 scientific novella Elective Affinities. In 1948, American author Thomas Dreier correctly explained human attraction as such:

“The mystery of human attraction is really no mystery; it is a matter of chemical affinity, as powerful as it often is seemingly incomprehensible.”

The concept-state dating site ReactionMatch.com, conceived by American chemical engineer Libb Thims, is a possible realization of this logic.

See also
● Affinity table
● Free energy table
● Elective affinity

References
1. Clark, John O.E. (2004). The Essential Dictionary of Science. New York: Barnes & Noble Books.
2. Dreier, Thomas. (1948). We Human Chemicals: the Knack of Getting Along with Everybody (pg. 66-67). Updegraff Press.

Further reading
● Korevaar, A. (1921). “On Chemical Affinity” (abstract), J. Phys. Chem. 25(4): 304-10.

External links
● Chemical affinity – Wikipedia.
● Chemical affinity – Britannica, 1911.