Concept
Molecule
Overview
A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and molecule is often used when referring to polyatomic ions.
A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not considered single molecules.
Concepts similar to molecules have been discussed since ancient times, but modern investigation into the nature of molecules and their bonds began in the 17th century. Refined over time by scientists such as Robert Boyle, Amedeo Avogadro, Jean Perrin, and Linus Pauling, the study of molecules is today known as molecular physics or molecular chemistry.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
In the original texts
Passages from public-domain books where Molecule is discussed.
We should expect transmission. In this way the modification of total pattern would transmit itself by means of a series of modifications of a descending series of parts, so that finally the modification of the cell changes its aspect in the molecule, thus effecting a corresponding alteration in the molecule,—or in some subtler entity. Thus the question for physiology is the question of the physics of molecules in…
Alfred North Whitehead, Science and the modern world
names the idea; states what it is; opens on it
For the kinetical theory of matter teaches us that a molecule is like a solar system or star-cluster in miniature. Unless we suppose that in all heating of gases and vapors internal work is performed upon the molecules, implying that their atoms are at considerable distances, the whole kinetical theory of gases falls to the ground. As for the term added to _P_, there is no more than a partial and roughly…
Charles S. Peirce, Chance, Love, and Logic
names the idea; states what it is; opens on it
The trajectory of a gaseous molecule may be regarded as formed of straight segments united by very small arcs corresponding to the successive impacts. The length of each of these segments is what is called the free path; of course this length is not the same for all the segments and for all the molecules; but we may take a mean; this is what is called the _mean path_. This is the greater the less the density of the…
Henri Poincaré, The Foundations of Science
states what it is; names the idea; opens on it
The theory that matter consists of “atoms”, _i.e._ of little bits that cannot be divided, is due to the Greeks, but with them it was only a speculation. The evidence for what is called the atomic theory was derived from chemistry, and the theory itself, in its nineteenth-century form, was mainly due to Dalton. It was found that there were a number of “elements”, and that other substances were compounds of these…
Bertrand Russell, Philosophy
states what it is; names the idea
Proceeding on these principles, it may be argued that the molecular mobility of a substance must depend partly on the inertia of its molecules; partly on the intensity of their mutual polarities; partly on their mutual pressures, as determined by the density of their aggregation; and (where the molecules are compound) partly on the molecular mobilities of their component molecules. Whence it is to be inferred that…
Herbert Spencer, The Principles of Biology, Volume 1
names the idea; opens on it
Philosophers who discussed Molecule
Related ideas
- Mantle (geology)
- Elementary particle
- Integer
- Latin
- Leucippus
- Light
- Aether (classical element)
- Atomic nucleus
- Organic chemistry
- Oxygen
- Quantum mechanics
- Merriam-Webster
- René Descartes
- The Sceptical Chymist
- Aristotle
- Robert Boyle
- Carbon
- Prentice Hall
- Chemical bond
- Fire (classical element)
- Air (classical element)
- Water (classical element)
- Earth (classical element)
- Kinetic theory of gases
Place in the tradition
Part of Atomism.