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John Thomson
Joseph John Thomson was born in Cheetham Hill, a suburb of Manchester on
December 18, 1856. He died 30 August 1940.
It was a British scientist and discoverer of the electron, of isotopes, and inventor of the
mass spectrometer. Known to make important contributions to understanding the
structure of atoms.
J.J. Thompson was awarded the Nobel Prize in Physics in 1906 "in recognition of the
great merits of his theoretical and experimental investigations on the conduction of
electricity generated by gas.
Thomson conducted a series of experiments on cathode ray tubes, which led to the
discovery of electrons. He used the cathode ray tube in three different experiments.
First
experiment
In their first experiment, he investigated whether the negative charges could be
separated from the cathode rays by means of magnetism. Thompson concluded that the
negative charge is inseparable from the rays.
Second
experiment
In their second experiment investigated if the rays can be deflected by an electric field
(which is characteristic of charged particles). Thompson found that the rays could
indeed bend under the influence of an electric field.
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Third
experiment
In the third experiment, Thompson determined the relationship between the charge and
mass of cathode rays by measuring how much is diverted by a magnetic field and the
amount of energy they carry. He found that the charge / mass ratio was more than a
thousand times the hydrogen ion, suggesting that the particles are very light or very
loaded. Thompson's conclusions were bold: cathode rays were made of particles called
"corpuscles", and these corpuscles came from within the atoms of the electrodes, which
means that atoms are actually divisible
Discovery of Isotopes
Thompson reviewed the positive rays in 1912, discovered how to use them to separate
atoms of different mass. The goal was achieved by diverting the positive rays in electric
and magnetic fields (mass spectrometry). He discovered that the Neon has two isotopes
(the neon-20 to neon-22).
In 1913, as part of its exploration in the composition of canal rays, Thomson channeled
a stream of ionized neon through a magnetic field and an electric field and measured its
deflection by placing a photographic plate in the beam path. Thompson observed two
patches of light on the photographic plate.
Thomson concluded that the neon gas is composed of two types of atoms of different
atomic masses (neon-20 to neon-22).