ATOMIC MODEL OF DEMOCRIT: ANTECEDENTS, CHARACTERISTICS, POSTULATES - PHYSICAL - 2025

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 arrives at his idea of ​​the atom after deep reflection.

Figure 1. Democritus reflected on what would happen if grains of sand were divided successively. Source: Pixabay.

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

Then he questioned himself this way: “If I divide the grain of sand, I will have two grains of sand. If I divide it again, I will have finer grains of sand. But… what if I divide it even more?

He then asked: "Can I continue the subdivision process indefinitely?" He then concluded that a point would be reached such that the grains cannot be further fragmented and the basic indivisible constituent is reached: the atom.

characteristics

Democritus failed to realize that the combinations of a few types of atoms were enough to explain all the diversity of matter. On the contrary, the philosopher thought that the atom of the sand grains was exclusive to the sand.

The same happened for wood and for 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 without internal structure. The atoms of the different materials could differ in size, shape, mass, giving the characteristics of that material.

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

Figure 2. According to Democritus, each material has its characteristic type of atoms and the space between them is empty. Source: Prepared by: F. Zapata.

Democritus, of course, lacked the experimental means to verify these claims. Neither did 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 the theory of Empedocles, 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 this theory, the concept of the atom had no place.

Democritus' atom: a long-forgotten model

For Aristotle the atomism of Democritus contradicted 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 the fraction of it was. The substance for Aristotle is intrinsically continuous.

The great influence and prestige of Aristotle caused that the ideas of Democritus were dismissed 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) took up the ideas of the atom and the elements. For Dalton there were some pure substances that were made up of elemental atoms.

Representation of Dalton's atomic model:: the atoms would be indivisible, indestructible and homogeneous tiny spheres.

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

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

The combinations of elemental atoms is unique for each substance, and is what we know today as molecules. For example water molecules or ethyl alcohol molecules.

Postulates of the Democritus model

The way 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 that, although not observable, are thus, forced by the force of logical reasoning.

Furthermore, the Greek rationalists distrusted the senses, since they believed them to be deceptive and instead, they fully trusted the logic of their reasoning.

Figure 3. Bust of Democritus of Abdera. Source: Wikimedia Commons.

For the radical and rationalist Democritus, everything, absolutely everything, was atoms and emptiness. The philosopher believed that even the soul was made up of atoms and a lot of emptiness. Therefore its postulates can be summarized as follows:

-Atoms are indivisible, indestructible, invisible and eternal.

-They can have movement and collide with each other, but never divide.

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

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

Atomism

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

So why is there cold or hot, sweet or sour, hard or soft? The answer is 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 catching. In contrast, iron atoms are rough, jagged, and can stick together and compact.

According to the atomism of Democritus they are the same eternal solid and indivisible particles that due to their movement can collide with each other and form conglomerates or separate, liquefy and evaporate. They change shape in appearance but are always the same and indivisible atoms.

Other Atomist Philosophers of Antiquity

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

In India, a philosopher and physicist named Kanada (a nickname for "atom eater") believed to have lived around the 2nd century BC or earlier, also formulated ideas about the atom.

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

Articles of interest

Schrödinger's atomic model.

De Broglie atomic model.

Chadwick's atomic model.

Heisenberg atomic model.

Perrin's atomic model.

Thomson's atomic model.

Dalton's atomic model.

Dirac Jordan atomic model.

Bohr's atomic model.

Sommerfeld atomic model.

References

1. Atomism. Recovered from encyclopedia.com
2. Berryman, S. Ancient Atomism. Recovered from plato.stanford.edu
3. Garrett, J. The Atomism of Democritus. Recovered from people.wku.edu.
4. Wikispaces. The history of the atom: Democritus. Recovered from: wikispaces.com.
5. Williams, M. Who Was Democritus? Recovered from: universetoday.com.