Discovery of the structure of the atom
Ernest Rutherford is credited with discovering the basic design of the
atom in a famous experiment in which he shot alpha particles moving at
high speeds towards a gold sheet. He detected what happened to these atoms
after they hit thegold with a sheet of glow in the dark material. When an
alpha particle hits the glow in the dark sheet it makes a bright spot
where it strikes.Here is a simplification of the lab setup which Rutherford used.
These alpha particles were made up of positive protons and neutral neutrons, so the overall charge of the
particle was positive. Most of
these alpha particles passed right through the gold atoms. This meant most
of the atom was really empty space. This empty space is the space between
the nucleus and the electrons. Some of the alpha particles were deflected
slightly. This was due to their attraction to passing electrons moving
around the outside of the atoms. A very small percentage shot straight
back. This was due to them hitting the very tiny nucleus head on and being
repelled from it. The diagram below shows the scattering of the alpha
particles after hitting the gold foil.
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