In human chemistry, the social molecule is the view of a collective society of people as an aggregate of human particles, human atoms, or human molecules. The term was coined in 1871 by English biologist Thomas Huxley: [1]

"Every society, great or small, resembles ... a complex molecule, in which the atoms are represented by men, possessed of all those multifarious attractions and repulsions which are manifested in their desires and volitions, the unlimited power of satisfying which we call freedom ... the social molecule exists in virtue of the renunciation of more or less of this freedom by every individual. It is decomposed, when the attraction of desire leads to the resumption of that freedom the expression of which is essential to the existence of the social molecule. The great problem of social chemistry we call politics [political thermodynamics], is to discover what desires of mankind may be gratified, and what must be suppressed, if the highly complex compound, society, is to avoid decomposition."

In 1970, American sociologist Robert Nisbet conceived of a “social bond” theory as what holds together the “social molecule”. [2] Variants of this concept include the social atom and the economic molecule.

References
1. (a) Huxley, Thomas. (1871). “Administrative Nihilism”, Fortnightly Review, pg. 536. Nov.
(b) Thims, Libb. (2008). The Human Molecule, (preview). Morrisville, NC: LuLu.
2. Nisbert, Robert, A. (1970). The Social Bond - an Introduction to the Study of Society (social molecule, 38, 45, etc.). New York: Alfred A. Knoph.