5.
"Shells off Tissue Paper"
A
few days after Marsden had been asked to look for alpha
particle scattering at large angles, Geiger came back
to Rutherford very excited. They had been able to get
scattering at very large angles, some even appearing
to bounce right back at the source of the particles!
Rutherford
described it as the most incredible event of his life,
"as if you fired a 15-inch shell at a piece of
tissue paper and it came back and hit you."
Such
huge deflections could not be explained by Thomson's
model of the atom, where charge was distributed evenly
throughout the atom. For such large deflections all
the positive charge had to be concentrated in a small
mass greater than the mass of the alpha particles.
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