The experiment to probe the structure of the atom performed by Hans Geiger
(Geiger counter) and Ernest Marsden in 1909, under the direction of Ernest
Rutherford at the Physical Laboratories of the University of Manchester.
(Rutherford gets all the credit, while his graduate students did the work.)
The Experiment
A beam of alpha particles, generated by the radioactive decay of radium, was
directed onto a sheet of very thin gold foil.
The gold foil was surrounded by a circular sheet of zinc sulfide (ZnS)
which was used as a detector: The ZnS sheet would light up when hit with alpha
particles.
The Results
Observation
Conclusion
the vast
majority of particles passed straight through the foil
Atoms are mostly made of open space
a very small percentage of particles were deflected
through angles much larger than 90 degrees
massive center with a + charge (the nucleus)
"It was quite the most incredible event that has ever happened to me in
my life. It was almost as incredible as if you fired a 15-inch
shell at a piece of tissue paper and it came back and hit you.
On consideration, I realized that this scattering backward must
be the result of a single collision, and when I made
calculations I saw that it was impossible to get anything of
that order of magnitude unless you took a system in which the
greater part of the mass of the atom was concentrated in a
minute nucleus. It was then that I had the idea of an atom with
a minute massive center, carrying a charge."
—Ernest Rutherford
Adjustment to the Model of the
Atom-Now with open space & positive nucleus
