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Democritus, theorized that atoms were
specific to the material which they composed.
In addition, Democritus believed that the atoms
differed in size and shape, were in constant
motion in a void, collided with each other. -
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Antoine Lavoisier (1743-1794) was the first person to make good use
of the balance. He was an excellent experimenter. He proposed the
Combustion Theory which was based on sound mass measurements. -
Experiments with gases that first became
possible at the turn of the nineteenth century
led John Dalton in 1803 to propose a modern
theory of the atom based on the following
assumptions. 1. Matter is made up of atoms
that are indivisible and indestructible. -
In 1897, J.J. Thomson discovered the electron
by experimenting with a Crookes, or cathode ray
, tube. He demonstrated that cathode rays were
negatively charged. In addition, he also studied
positively charged particles in neon gas. -
And Marie was proven right: in 1898 the Curies
discovered two new radioactive elements: radium
(named after the Latin word for ray) and polonium
(named after Marie's home country, Poland) -
In 1911, he was the first to discover that atoms
have a small charged nucleus surrounded by
largely empty space, and are circled by tiny
electrons, which became known as the
Rutherford model (or planetary model) of the atom. -
In 1915, Einstein published the general theory of
relativity, which he considered his masterwork.
This theory found that gravity, as well as motion,
can affect time and space. -
Planck performed the only experiments of his
scientific career, studying the diffusion of hydrogen
through heated platinum, but transferred to
theoretical physics. -
Bohr was working for the Nobel laureate
J.J. Thompson in England when he was introduced
to Ernest Rutherford, whose discovery of the
nucleus and development of an atomic model. -
His oil drop experiment helped to quantify the
charge of an electron, which contributed greatly
to our understanding of the structure of the atom
and atomic theory. -
His new theory was based only on what can be
observed, that is to say, on the radiation emitted by
the atom. -
Schrödinger used mathematical equations to
describe the likelihood of finding an electron in a
certain position. This atomic model is known as the
quantum mechanical model of the atom. -
Soon realized that the newly discovered neutron,
as an uncharged but fairly massive particle, could
be used to probe other nuclei. -
Louis inherited the title of duke. Maurice, who was
also a physicist and made notable contributions to
the experimental study of the atomic nucleus,
kept a well-equipped laboratory