Early Models of Atoms

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III. Early Models of Atoms

A) Rutherford Model of Atom (1911)

Model Based on
Alpha Particle Scattering Experiment

Rutherford Experiment - www.CosmoLearning.com

(onsite)

Rutherford Experiment
Molecular Expressions

Alpha Particle Scattering
St. Mary's Physics Online

Rutherford shot alpha particles at a thin gold foil to learn about the atom

Prentice Hall
Onsite

Alpha particle

Thin gold foil

What explains their
curved path??

Repulsive electrical force
(A.K.A. coulomb force)

Unexpected:
Large deflection angles

Indicates strong forces

Rutherford Scattering Applet
- © 1995-2007 by Michael W. Davidson and Florida State University

Rutherford Scattering
Michael Fowler

Conclusions:

1) Most of the volume of the atom is ...

empty space

(nucleus 1 x 10^-15 m)

Did you know ...

A neutron star is created when a massive star runs out of fuel and collapses. This tremendous gravitational collapse squeezes all the empty space out of the atom. Electrons merge with protons and create neutrons.

The density of a neutron is so enormous that a teaspoon of a neutron star would weigh 20 billion pounds!!!

- Cornell Astronomy

http://www.astro.cornell.edu/academics/courses/astro201/neutron_star.htm

Did you know ....

If the atom were the size of a football stadium

the nucleus would be
the size of a....

pea

- Wikipedia

That's why most alpha particles go straight through!!!

2) Virtually all mass atom found in ...

... the nucleus

3) Strong, positive charge in the center of atom

That's why positive alpha particles were curved so strongly

"Other Side of Infinity" Movie Trailer

Bohr Model of Atom