1. History of Atomic Theory
Research the discoveries and experiments of scientists and their contribution to “atomic theory”
use textbook & internet
Public/All/Kent/Ato mic Research
site your sources
Create a poster

2. Democritus & Dalton Democritus (460 BC)
First to develop the idea that matter was made of “atoms”.
Dalton (1803)
Proposed the atomic theory
atoms are indivisible & indestructible
elements have unique atomic masses

3. Mendeleev (1869) Developed the first basic periodic table
Table was arranged by atomic weight
was able to predict elements which hadn’t been found

4. J.J. Thomson (1898) • Discovered electrons (-e)
• Atoms have — & + charges

5. Rutherford (1911) Discovered the positively charged nucleus
shot positively charged particles through gold foil
electrons moved in circles

6. Bohr (1913)
Electrons move in specific energy levels (orbits) around the nucleus

7. Schrodinger (1926)
Described electrons as waves
Electron cloud

8. Chadwick (1932)
Neutrons (and
protons) made up
the nucleus

9. Evolution of the Atom

10. Evolution of the Atom