Events
John DaltonModel: His model was called the billiard ball model. He interpreted the atom to be a ball-like structure.
Experiment: Dalton experimented with gases. His experiments led to a discovery that the total pressure of a
mixture of gases amounted to the sum of the partial pressures that each individual gas
exerted while occupying the same spaceJoseph John ThomsonModel: His model was called the plum pudding model of the atom.
He thought of this because he discovered the electron by
experimenting with a cathode-ray tube.
Experiment: He experimented with cathode-ray tubes and he found that all
atoms contain tiny negatively charged subatomic particles or electrons. He was
the person who discovered that an atom has a smaller part called electrons.Ernest
RutherfordModel: His model shows that an atom is a mostly empty space
with electrons orbiting a fixed, positively charged nucleus. He also
discovered protons and the nucleus.
Experiment: His most famous experiment is the gold foil experiment.
A beam of alpha particles was aimed at a piece of gold foil.
Most alpha particles passed through the foil, but a few were scattered
backwardNiels
BohrModel: His model is the Bohr model of an atom.
shows the atom as a small, positively charged
a nucleus surrounded by orbiting electrons.
Experiment: He proposed a theory for the hydrogen
atom based on quantum theory that energy is transferred
only in certain well-defined quantities.James
ChadwickModel: His model was the quantum mechanical model of the atom.
He bombarded beryllium atoms with alpha particles and an unknown
radiation was produced.
Experiment: He had a hypothesis and wanted to test it so he put a piece
of beryllium in a vacuum chamber with some polonium. The polonium
emitted alpha rays, which struck the beryllium after it was struck
it emitted mysterious rays.Modern (Schrodinger)Model: The current model of the atom has a nucleus in the center
surrounded by neutrons, protons, and electrons.
Experiment: Erwin Schrödinger's most famous experiment in modern
time is “Schrödinger's cat”. A cat is in a box with a vial of poison.
The vial breaks if an atom inside the box decays. The atom is superposed in
decay and non-decay states until it is observed, and thus the cat
is superposed in alive and dead states
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