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Leucippus atomic model: postulates, limitations, importance

We explain the Leucippus atomic model with postulates, limitations and importance. The atomic model of Leucippus is the conception of matter proposed by the Greek philosopher Leucippus of Miletus, who lived in the 5th century BC This Hellenic thinker proposed, around 440 BC, that matter was discontinuous and was made up of tiny particles called atoms.

Leucippus atomic model: For the Greek philosopher Leucippus, matter was composed of atoms similar to solid marbles.
For the Greek philosopher Leucippus, matter was composed of atoms similar to solid marbles.

The word “atom” comes from the Greek word that means indivisible. For this reason he is considered the founder of atomism in Ancient Greece, although some attribute this distinction to the Phoenician sage Mosco of Sidon, of whom very little is known. Leucippus atomic model

The truth is that the ideas of Leucippus were in direct opposition to those of other thinkers, in particular Empedocles, Plato and Aristotle, who argued that matter was continuous and was composed of four elements: earth, air, fire and water.

Very little is known of Leucippus’s life, and some even doubt that he really existed. Nor is his writings known directly, but only through the ideas of other thinkers.

On the left the Greek philosopher Leucippus and on the right Democritus, defenders of the concept of the atom in ancient Greece.
On the left the Greek philosopher Leucippus and on the right Democritus, defenders of the concept of the atom in ancient Greece.

And it is that Aristotle himself recorded Leucippus as the founder of atomism. This atomic model is also known as the Leucippus and Democritus model, since Democritus of Abdera defended the atomist thesis.

Characteristics of the atomic model of Leucippus

The atomism of the ancient Greeks did not come from scientific experimentation, but from careful reflection on nature.

It is evident that things change over time, move and change constantly, so the Greek thinkers meditated on these facts and, with the means at their disposal, tried to explain them.

They wondered about the following: if we divide something, can we do it indefinitely, getting smaller and smaller pieces each time? Or will there come a time when the last fragment is found, the smallest possible of all?

Main postulates

The atomic model of Leucippus and Democritus considers that the atom is:

-Indivisible, and therefore lacks internal structure.

-So small that it is not possible to see it with the naked eye, in fact it is invisible.

-Completely solid.


It also proposes that:

-The movement is a characteristic of atoms, they can even collide with each other, without fragmenting or dividing in any way.

-The atom is also the basis of everything that exists, not only matter, but also intangible things such as the soul.

-The universe is made up of atoms.

-Each substance has its own atoms: for example, the atoms of wood are their own, those of rocks are exclusive to rocks and so on.

-Atoms can have different shapes and sizes. When combined, they give each substance its different properties.

-The atomic model of Leucippus assumes the existence of a vacuum, which is the space not occupied by atoms.

Importance of the model

Despite being an extremely primitive atomic model, its virtue is that it was one of the first to propose the existence of the atom, as the smallest constituent of matter.

He further established that the different types of atoms had to be combined in various ways, thus explaining the diversity of substances known to the Greeks. This is a first glimpse of the concept of chemical bonding. Leucippus atomic model

According to Leucippus, this explained the differences between wood and metal, for example.

Other philosophers like Epicurus of Samos extended these ideas to the known universe, including living beings. According to this philosophy, the mind is nothing other than atoms in motion. And this is not due to divine designs, but simply to the nature of things.

For his part, the Roman poet Lucretius spread atomistic ideas in his work entitled “The Nature of Things”, with little success.


It is clear that Leucippus’s atomic model has numerous limitations, since its foundation was in reasoning and not in experimentation. For example, we mention that:

-The atom is not solid, but has an internal structure, being made up of electrons, protons and neutrons. The latter in turn form the atomic nucleus.

-The model does not explain how the combinations that give rise to the diversity of known compounds are achieved.

-An oxygen atom in water is not different from the oxygen atom in any other substance. Leucippus and Democritus believed that the atoms of each substance were special and unique, that is, there were atoms of water, wood, iron and so on.

-The atom is neither invisible nor indivisible. Actually some unstable atoms fragment emitting energy and particles: they are radioactive atoms. Leucippus atomic model

The fate of the Leucippus model

Plato and his disciple Aristotle were staunch opponents of Leucippus’s atomic model, although Aristotle came to comment on the model in his works. Leucippus atomic model

Despite this, the experiments of Heron of Alexandria (1st century AD) and his early turbines showed that air could be compressed and provided additional support for the ideas of Leucippus  and Democritus. This was, perhaps, the first experimental evidence in favor of the atom.

However, Aristotle’s prestige was such that his ideas prevailed for 2,000 years, until at the beginning of the 19th century the English chemist John Dalton explained stoichiometric ratios, this time based on experimental facts and not just reasoning.

It would take a few more years for the atom to begin little by little, to reveal its secrets to researchers.

Other influences on Leucippus’s atomic model

It is more than likely that Leucippus and Democritus were influenced by the ideas of other thinkers and also by those that came from India, Egypt and even China. Kanada, a Hindu thinker who perhaps lived before 200 BC, is said to have believed that the world was made of particles. Leucippus atomic model

This is not surprising; after all, the preoccupation with knowing the constitution of things is undoubtedly much older. The Chinese, for example, knew about some interesting chemical processes, such as the distillation of alcohol, for at least 200 years before the time of Leucippus.

Furthermore, by the time Leucippus developed his theories, metallurgy was widely used and surely had already given much to think about the behavior of matter and its properties.

And not only Leucippus and Democritus believed in the existence of particles as the ultimate constituents of matter, but other thinkers such as Anaxagoras of Clazómenas (present-day Turkey), who firmly believed in the existence of the spermata , tiny particles endowed with intelligence, which make up everything. how much exists. Leucippus atomic model

But this model was the beginning of the path that science still travels, in search of the many secrets that matter still hides.

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