1.
Atomic
Theory
The History and Development of the Atomic
Theory
The atom is considered the smallest particle
of matter.
Many scientist tried to study and investigate
its existence.
From 18th century until today our view of the
atom has changed because of new ideas and
advancementsin technology.
The atomic model is a representation of what
an atom could look based on observations and
scientific evidence that how atoms behave.
THE STRUCTURE MATTERS:
THE DEVELOPMENT OF
ATOMIC STRUCTURE
Figure 11.1

2.
1. All things are composed of
atomos, which may be too small
to be seen by the naked or
unaided eye and cannot be broken
down to smaller parts.
2. There are empty spaces between
these inner structures of matter.
3. Matter is made up of solid
particles.
4. Matter has a uniform structure all
throughout.
5. Matter varies in shape, size, and
weight.
Proposed the following ideas
about atoms
Figure 11.2

3.
Aristotle and his idea that
matter was made up of four
natural elements
• Aristotle believe that matter was
made up of four natural elements
where the ratio of these four
elements affects the property of
matter and can also be
transformed into one another.
Because Aristotle was more
famous and influential than
Democritus, the ideas of the latter
never took hold. It took more
2000 years before the concept of
atom reemerged.
Figure 11.3
Aristotle and his idea that matter was made up of four
natural elements

4.
• Have you ever
experienced that your
idea was not accepted
because of someone who
is more famous or
influential than you has
another idea even though
yours might be better?