Democritus and Leucippus were ancient Greek scholars who were the first proponents of the atomic theory, proposing that all matter is made up of tiny, indivisible particles called atoms. They believed atoms are indestructible, impenetrable, and unchanging, moving continuously in empty space and combining to form clusters. While their ideas formed the basis of modern atomic theory, they were opposed by philosophers like Anaxagoras, Empedocles, Plato, and Aristotle, who believed matter was composed of fundamental elements like earth, water, air and fire instead of atoms.

1. Ideas of the Asian Greeks on
Atom

2. Democritus of Abdera (460 - 370 B.C.) Leucippus of Miletus (c.500 B.C.)
Greek scholars who believed that matter could be divided into tiny particles until
such point where it can no longer be divided anymore. They became the first
proponents of the atomic theory.

3. 1. All matter is made up of tiny, indivisible particles called atoms, which come
from the Greek word atomos meaning uncuttable. The atoms are indestructible,
impenetrable, and unchangeable.
2. The atoms make up the universe as they are continuously moving in a “void”
that surrounds them, repelling each other when they collide, or combining into
clusters.
3. Atoms are completely solid which means that there is no void or empty space
inside that will make them prone to disintegration or destruction.
4. Atoms are homogeneous in nature. They have no internal structures.
5. Atoms come in different shapes and sizes.
Their early ideas on atoms are summarized below.

4. Ideas that served as arguments against atomism:
1.Anaxagoras
-argued that there was an infinite number of
elementary natural substances in the form of
infinitesimally small particles that combined to
comprise the different things in the universe.
-stated that everything is made up of
four eternal and unchanging kinds of matter,
fire, air (all gases), water (all liquids and
metals)
and earth (all solids).
2.Empedocles

5. 3.Plato
-further expanded Empedocles’ theory by
saying each of the four kinds of matter is
composed of geometrical solids (the “Platonic
solids”) further divisible into triangles. When
rearranged, these triangles could cause the
apparent transformations between the four
basic kinds of matter.
4.Aristotle
-believed that everything in the universe is
made up of the four elements, air, fire, water,
and earth. He stated that believing in atoms
would mean putting restriction on the gods,
who have the power to divide elements
smaller than the atom.

6. A HISTORY OF THE ATOMS:
THEORIES AND MODELS
This will shows the atomic models and how they developed.

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