This document discusses the history of atomic theory and models from ancient Greek philosophers to modern physics. Democritus first proposed that matter was made of indivisible particles called atoms. He believed atoms were different shapes and sizes and made of the same material. Later models include Dalton's model of atoms, Thomson's raisin bun model, Rutherford's planetary model, Bohr's nuclear model, and the modern quantum mechanical model where electrons exist as probability clouds rather than definite orbits.

1. Atomic Theory
and
Models
Jeri Mayah P. Asuncion
BEED 1-3 DAY

2. Democritus
He asked: Could
matter be divided
into smaller and
smaller pieces
forever, or was
there a limit to the
number of times a
piece of matter
could be divided?

3. Atomos
 His theory: Matter could
not be divided into
smaller and smaller
pieces forever, eventually
the smallest possible
piece would be obtained.

4. Atomos
 To Democritus, atoms
were small, hard
particles that were all
made of the same
material but were
different shapes and
sizes.

5. The eminentThe eminent
philosophersphilosophers
of the time,of the time,
AristotleAristotle andand
PlatoPlato, had a, had a
moremore
respected,respected,
theory.theory.

6. Dalton’s Model

7. Thomson’s Model
Raisin Bun Model

8. Rutherford's Model

9. Rutherford's Model

10. Bohr's Model

11. Chadwicks's Model

12. The Modern Model
 Today’s atomic model
is based on the
principles of wave
mechanics.
 According to the
theory of wave
mechanics, electrons
do not move about an
atom in a definite
path, like the planets
around the sun.

13. Electron Cloud:
 A space in which
electrons are likely to be
found.
 Electrons whirl about the
nucleus billions of times
in one second
 They are not moving
around in random
patterns.
 Location of electrons
depends upon how much
energy the electron has.