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igcse physics notesprinted 111 · PDF 111
124 pagesrevision 46936
printed 111 · PDF 111
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particles at a thin sheet of gold foil, and observed how the particles were
deflected.
Observations: Most alpha particles passed straight through the foil with
very little or no deflection.
Some were deflected at very large angles.
An even smaller amount of particles were deflected straight backwards.
Conclusions: This led to the conclusion that the atom is mostly empty
space with a very small nucleus in the center.
The nucleus is positively charged because it repelled the positively charged
alpha-particles.
The nucleus contains most of the mass of the atom.
The Nucleus and subatomic particles
The nucleus is composed of protons and neutrons.