Events
Democritus
Democritus was one of the first Greek scientists
to theorize that matter was made of small
indivisible particles.John Dalton
John Dalton was the first scientist the proposed
the atom with ways the atom workedMicheal Faraday
Micheal Faraday theorized that the atom
contained an electrical component that also was
responsible for the joining of compoundsMarie and Pierre Curie
Marie and Pierre Curie had discovered radiation
by placing uranium salt on a photographic plate
wrapped in black paperJ. J. Thomson
J. J. Thomson discovered that the atom
contained a positive and negative charge by
experimenting with a Crookes tubeErnest Rutherford
Ernest Rutherford found out by aiming alpha
particles at a sheet of gold foil that the atom
was composed of a small, dense, positively
charged nucleus surrounded by a cloud of
negatively charged electronsErwin Schrodinger
Erwin Schrodinger had used mathematical
equations to find the probability of an electron
being in any one place around the nucleus and
had made an electron density mapNeils Bohr
Neils Bohr had proposed that the electrons have
a concentric circular orbit around the nucleusJames Chadwick
James Chadwick had by bombarding beryllium
with alpha particles that a unknown radiation
was being emitted and that it was coming from
a neutrally charged particle which was named
the neutronRobert Millikan
Robert Millikan discovered the charge of an
electron by dropping oil between electrodesJoseph Luis Proust
Joseph Luis Proust proposed that all compounds
were the same proportions of mass as the
combined elements despite how they were
madeAntoine Lavoisier
Antoine Lavoisier had discovered that mass was
conserved in a chemical reaction and that the
total mass of the product was the always the
same as the total mass of the starting materials
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