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Atomic model of Democritus: antecedents, characteristics, postulates

Atomic model of Democritus: antecedents, characteristics, postulates

The atomic model  of Democritus was the first to introduce the idea that matter consists of indivisible basic elements called “atoms”. In fact, the word atom means indivisible.

Democritus was a Greek thinker who lived between 460 BC and 370 BC. He was the father of atomism and a disciple of other Greek philosophers such as Leucippus and Anaxagoras. Democritus reaches his idea of ​​the atom after deep thought.

It is said that, standing on the beach, he thought that the grains of sand were the result of the fragmentation of the rocks and that, despite their small size, they still had rocky characteristics.

So he asked himself this way: “If I divide the grain of sand, I will have two grains of sand. If I split it again, I’ll have finer grains of sand. But… what if I split even more? ”.

Then he asked himself, “Can I continue the subdivision process indefinitely?” So he concluded that a point would be reached where the grains can no longer be broken down and the indivisible basic constituent will be reached: the atom.


Democritus did not realize that combinations of some types of atoms were sufficient to explain all the diversity of matter. On the contrary, the philosopher thought that the atom of the grains of sand was unique in sand.

The same happened with wood and any other substance. Each had its own type of atom. In conclusion, for Democritus, the atom was the smallest possible fraction of each substance.

Furthermore, the atom was solid and had no internal structure. The atoms of different materials can differ in size, shape, mass, giving the characteristics of that material.

Among the conglomeration of atoms that make up any material, there is nothing but emptiness.

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Democritus, of course, lacked the experimental means to verify these claims. Nor two of the most prestigious Greek philosophers: Aristotle and Plato, who did not share these ideas about the atom.

On the contrary, Aristotle and Plato supported Empedocles’ theory, which establishes four basic elements: earth, air, water and fire as fundamental components of matter.

It was the different combinations of these basic elements that gave rise to all the diversity of matter. And in that theory, the concept of the atom had no place.

Democritus Atom: a long-forgotten model

For Aristotle, Democritus’ atomism contradicts the concept of substance, in which the proportion of the elements (earth, air, water and fire) had to be maintained at all costs, no matter how small their fraction. Substance for Aristotle is intrinsically continuous.

The great influence and prestige of Aristotle caused the ideas of Democritus to be rejected and forgotten for a long time. Almost two thousand years have passed since then, when the English chemist John Dalton rediscovered the Democritus atom and reformulated the theory.

In 1803, the English chemist John Dalton (1766-1844) adopted the ideas of the atom and the elements. For Dalton, there were some pure substances made up of elementary atoms.

The different combinations of these atoms, in different proportions, are the explanation for all the diversity of matter.

For this scientist, a non-elementary substance is composed of particles which, in turn, are the union of two or more elementary atoms. And these substances can be separated into the elemental substances that compose it.

Combinations of elementary atoms are unique to each substance and are what we know today as molecules. For example, water molecules or ethyl alcohol.

Postulates of the Democritus Model

How Democritus conceived his model of the atom is far from the current scientific method. One of the philosophical currents of ancient Greece, rationalism, does not hesitate to affirm the existence of things which, although they are not observable, are thus forced by the force of logical reasoning.

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Furthermore, the Greek rationalists were suspicious of the senses, believing them to be deceptive and, instead, totally reliant on the logic of their reasoning.

For the rationalist and radical Democrat, everything, absolutely everything, was atoms and void. The philosopher believed that even the soul was composed of atoms and very empty. Therefore, their postulates can be summarized as follows:

Atoms are indivisible, indestructible, invisible and eternal.

-They can move and collide with each other, but they never split.

-The atom is the basis and justification of everything, there is no greater power, there is no greater objective than the atom, according to Democritus.

The world and the universe only follow the laws of atoms, there is nothing else.


The philosophical school of atomism stated that matter by its elementary constituents is eternal and indestructible, the changes observed by the senses are only superficial, basically everything is immutable and eternal.

So why is it hot or cold, sweet or sour, hard or soft? The answer lies in the atoms, but in each state there are different movements or configurations.

Water is soft because its atoms are rounded solids that roll over each other and have no chance of getting stuck. Iron atoms, on the other hand, are rough, irregular and can pick up and compress.

According to the atomism of Democritus, it is the same eternal solid and indivisible particles which, due to their motion, can collide with one another and form conglomerates or separate, liquefy and evaporate. They change the shape of appearance, but they are always the same atoms and indivisible.

Other Atomist Philosophers of Antiquity

After Democritus, the philosopher Epicurus of Samos (341-270 BC) also maintained the belief in the atom in his own school of thought.

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In India, a philosopher and physicist named Kanada (a nickname that translates to “atom eater”) and who believed he lived around the 2nd century BC or earlier, also formulated ideas about the atom.

Among them he spoke of the concept of indivisibility and eternity. He also claimed that the atom had at least twenty qualities and four basic types, enough to describe the entire universe.

articles of interest

Schrödinger Atomic Model.

Broglie Atomic Model.

Chadwick Atomic Model.

Heisenberg Atomic Model.

Atomic model of Perrin.

Thomson atomic model.

Dalton Atomic Model.

Atomic model of Dirac Jordan.

Bohr atomic model.

Sommerfeld atomic model.

Current atomic model.

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