1. RUTHERFORD
THEORY
Albert C. X10/1 | Julius C. X10/13 | Nicholas S.W. X10/17 | Sinclair K. X10/19

2. Lenard’s Experiment
Lenard’s experiment was meant to proof that if Thomson’s
atomic model is right, electrons that go through the
aluminum plate should’ve experienced energy loss, so the
electrons should be easily refracted.
In Lenard’s experiment, he shows that Thomson’s atomic
model is wrong because he found that most of the electrons
were not refracted. This shows that electrons are not spread
evenly.

3. Continuation of Lenard’s Experiment
In 1911, Ernest Rutherford was interested to continue
Lenard’s experiment by replacing electrons with
particle which consist of positive charge. This
experiment was conducted by Hans Geiger & Ernst
Marsden.

4. Who is Ernest Rutherford?
He is a New Zealand-born, British chemist and
physicist. In 1914, he was knighted and two
years later, he was awarded the Hector
Memorial Medal. Under him, Nobel Prizes were
awarded to James Chadwick for discovering
neutron. Rutherford remains the only science
Nobel Prize winner to have performed his most
famous work after receiving the prize.

5. Rutherford’s research
• “rays” / particles
• Theory of protons
• Detector for electromagnetic waves

6. What are rays / particles?
• High speed particles
• Made up of two protons and two neutrons
• Is a nucleus, same as the nucleus of a
common atom of helium
• Don’t have electrons around it
• Type of ionizing radiation
• will loose all their energy in just a couple
inches of travel in air

8. What Rutherford did?
He directed the rays to a gold plate
surrounded by screen coated with sulfide zinc
which are around the plate.

9. What happened?
1. Some of the particles pass the empty space
go trough
Nucleus
Particles Atoms of Gold
foil

10. 2. Some of the particles that approach the
nucleus are deflected
Nucleus
Particles
Atoms of Gold
foil

11. 3. Some of the particles that hits the nucleus
are bounced back
Particles Nucleus
Atoms of Gold
foil

12. Conclusion of Rutherford’s Theory
• A large fraction of the room in an atom is empty
– Indicated by most of rays pass through the plate
Nucleus
Particles Atoms of Gold
foil

13. • Nucleus is tiny yet very dense core of atom
– Indicated by little amount of refracted rays
Particles Nucleus
Atoms of Gold
foil

14. • Electrons go circle the nucleus with high speed
– Indicated by the electrons that are not attracted by
protons inside the nucleus

15. • The charge of the nucleus is the same as particle’s,
which is positive
– Indicated by the deflected rays that deflected due to
repulsion forces of similar charge.
Nucleus
Particles
Atoms of Gold
foil

16. Rutherford’s Theory Weakness
Based on Rutherford’s theory that
states electrons go around the
nucleus will stay on its path is
unproved. Based on physics
classical mechanic law, that objects
that going around on circular path
will release its energy in the form of
radiation, so the electron will be
going closer to the nucleus. But
then, Rutherford’s theory is
supported by Bohr’s theorem.