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Models of the atom: proton-neutron-electron view (top left), modern artistic view (top middle), charge cloud view (top right), the photon-electron view (bottom left), Bohr model view (bottom middle), and atomic atheism view (bottom right).

In terms, atom (TR:1029) (LH:63) (TL:1092|#20), from Epicurus' 300BC Greek terms: atomos (ατομος) (NE:681), atomous (άτόμους) (NE:1081), or atomois (άτόμοις) (NE:691), from a- (α-), meaning: “not”, + temno- (τεμνω-), meaning: “cut, intersect”[1] or "unable to be cut"[2], referring to thing, body, or primary substance, or first principle that "cannot be cut" (Eusebius, c.313), defined in modern terms as a bound state of protons, neutrons, and electrons, which come in 92 naturally occurring varieties, called "elements", each defined by the characteristic number of protons in nucleus or core.


Pre-atomic theory

Pre-atomic theory, in some semblance or form, is found in the ideas of Xenophanes, a student of the Pythagorean school, who was an associate of Empedocles (four elements philosopher). Xenophanes taught Parmenides. Parmenides taught Zeno and or Melissus.[3] Zeno and Melissus, in turn, taught Leucippus, who initiated atomic theory.


In 450BC, Leucippus introduced "atomic theory", according to which all things were comprised of small particles, conceptualized as follows (modern icon):

Atom (icon).png

which moved in a void or empty space, and when combined, formed bodies, e.g. rocks, plants, animals, humans.


A basic picture of what the "atoms" of Democritus were conceptualized to be, based on verbal statements.

Leucippus, in turn, taught his atomic theory to Democritus; some of his views are shown below:

“We see changes in things because of the rearrangement of atoms, but atoms themselves are eternal. Words such as ‘nothing’, ‘the void’, and ‘the infinite’ describe space. Individual atoms are describable as ‘not nothing’, ‘being’, and ‘the compact’. There is no void in atoms, so they cannot be divided. I hold the same view as Leucippus regarding atoms and space: atoms are always in motion in space.”
Democritus (c.420BC), Source; Rex Pay fragment #48 [4]
“Nothing exists except atoms and empty space; everything else is opinion.”
— Democritus (c.420BC), Source; Rex Pay fragment #49[4]

Depictions of how Democritus visualized atoms are shown adjacent.


In 300BC, Epicurus, unsatisfied with the "chaos" model origin of things, sought out the works of Leucippus, and advanced atomic theory. The school founded by Epicurus, however, differed on many points, as compared to Democritus.


In 60BC, Lucretius, in his On the Nature of Things, presented the first-main book on atomic theory, but of note he does not employ the term "atom" or atomos, but rather terms such as "corpora prima" (§1.61), which later gets translated into the English term "atom".


The etymology of the term "atom", traditionally, has been that it derives from the Greek atomos (ατομος) (NE:481) meaning: “uncutable”. This, however, may be a retrospectively derived coining or etymology?

The theory of the "atom", as we now define this term, originated from Leucippus, a student of Zeno and or Melissus, both of whom themselves being students of Parmenides, who in turn was a student of Xenophanes.[3] This group, however, does not seem to have used the term "atom".

In 420BC, Democritus, the student of Leucippus, likewise does not seem to use the term "atom", but rather employs the term: "thing", "the solid", and "what is" for the principle substance of bodies.[3]

In 300BC, Epicurus, to give an example of Greek-to-English, discussed the size of "atoms", using the Greek words: άτόμους (NE: 1081) and άτόμοις (NE:691), as follows:[5]

Greek English
Λλλά μήν ούδέ δεί νομίζειν πάν μέγεθος

έν ταίς άτόμοις όπάρχειν, Υναμή τά

φαινόμενα άντιμαρτυρρ {...} πάν δέ

μέγεθος ίιπάρχον ούτε χρήσιμδν έστι

πρός τας τών ποιοτήτων διαφοράς,

άφϊχθαί τε άμ' έδει καί πρός ήμάς όρατάς

άτόμους• δ ού Θεωρείται γινόμενον

Nor, moreover, must we suppose

that every size exists among the

atoms, lest the appearances contest

this, {...} but the existence of every

size of atoms is not required for the

differences of their qualities, and at

the same time visible atoms would

have to come within our ken, which is

not observed to happen ...

In these Greek terms: atomos (ατομος) (NE:681), atomous (άτόμους) (NE:1081), or atomois (άτόμοις) (NE:691), it is difficult to detect any secret name meaning, in respect to isopsephy or what not?

In 60BC, Lucretius, in his On the Nature of Things, likewise does not employ the term "atom" or atomos, but rather terms such as "corpora prima" (§1.61). Specifically, eleven terms in Lucretius are found with the sense of “atoms," namely, primordia, ordia prima, prima, principiorum (is), corpora, corpuscula, semina, elementa, figurae, particulae, materia. Of these, corpora and semina alone correspond to their Greek prototypes, cáuata and orrépuata.


In c.50BC, Cicero, in his commentary on Lucretius, uses four words in Latin that occur with the meaning of “atoms”, namely: atomi, individua, corpora, and corpuscula.[6]

Atomus, as in Epicurus, is the special and particular term of Cicero for the ultimate unit of matter. Cicero naturalized the word in the Latin, through which it has passed into modern scientific nomenclature. He defined the term: atomos id est corpora individua propter soliditatem (Fin. I 17). The use of the term is entirely identical with that of Epicurus.”
— Katharine Reiley (1909), Studies in the Philosophical Terminology of Lucretius and Cicero (pg. #)

Here, presumably, the term "atom" had become modern?


The following is one of the earliest etymological statements of the term of atom:

“It is called the ‘atom’ not because it is the smallest thing, but because it cannot be cut, since it cannot be affected and contains no void.”
Eusebius (c.313), Praeparatio Evangelica (§: XIV.14.5) [3]

Alternatively, in recent decades, some have conjectured that "atom" derives from the Egyptian god Atum, the original "land" mass (or land god) that arose from the mythical watery Nun or chaos of beginning (see: Atoms and Atum).[7]


The following are related quotes:

“When I taught physics in secondary school in 1891, the invisible and indestructible atom was the foundation upon which the scientific structure was built. Some of my naïve pupils were skeptical and asked if I were telling a fairy tale.”
Judson Herrick (1956), The Evolution of Human Nature (pg. 33)
“If, in some cataclysm, all scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or atomic fact, or whatever you wish to call it) that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence you will see an enormous amount of information about the world, if just a little imagination and thinking are applied.”
Richard Feynman (1964), Lectures on Physics (pg. #) [8]
Hydrogen is a light, odorless gas, which, given enough time, turns into people.”
John Wiley (1995), “Phenomena, Comments, and Notes”, Smithsonian Magazine, Dec [9]

End matter

See also


  1. Challoner, Jack. (2018). The Atom: the Building Block of Everything (pg. 13). Publisher.
  2. Lucretius. (60BC). On the Nature of Things (translator: Walter Englert) (note #5, pg. 3). Hackett, 2003.
  3. 3.0 3.1 3.2 3.3 Taylor, C.C.W. (1999). The Atomists: Leucippus and Democritus: Fragments: a Text and Translation with a Commentary by C.C.W. Taylor (Leucippus [pre-atomic theory], pgs. 53-54; thing, solid, what is, pgs. 70-71; cutting, pgs. 78-79). University of Toronto Press.
  4. 4.0 4.1 Pay, Rex. (2005). “Democritus”,
  5. Bakker, Fredericus. (2016). Epicurean Meteorology: Sources, Method, Scope and Organization (pg. 18). Brill.
  6. Reiley, Katharine. (1909). Studies in the Philosophical Terminology: of Lucretius and Cicero (four names, pg. 66). Columbia University.
  7. Atoms and Atum – Hmolpedia 2020.
  8. Feynman time capsule wisdom – Hmolpedia 2020.
  9. Wiley, John P. (1995). “Phenomena, Comments & Notes: Today’s physics allow outrageous possibilities: faster-than-light travel across the galaxy, or even our learning to make new universes to specification” (WB), Smithsonian Magazine, Dec.

Further reading

  • Melsen, Andrew. (1952). From Atomos to Atom: the History of the Concept of the Atom (translator: Henry Koren) (pgs. 18-19). Dover, 2004.


  • Anon. (2021). “A Better Way to Picture Atoms” (YT), Minute Physics, May 19.

External links

  • Atom – Hmolpedia 2020.
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