John Joseph Thomson (1856-1940) was born in Manchester, England on
the 18 of December 1856. In 1876 he won a competition to attend Cambridge University in
England, where he lived for the rest of his life. At the age of 28 he was appointed
Cavendish Professor of Experimental Physics at Cambridge University. In 1906 he was
awarded the Nobel Prize for physics for his research into cathode rays.
Thomson worked with cathode rays and believed them
to be particles mainly because they were deflected in magnetic fields. He started to
explore X rays and demonstrated their power to make a gas electrically conductive. After
this he returned to his research on cathode rays. He decided that cathode rays were
negatively charged because of the way they were deflected in one of his experiments and
because the charge to mass ratio was always the same. He suggested that the arrangement
and number of these cathode rays, later named electrons, would determine the chemical
properties of an element.
He produced a theory of how matter was made up
called the "Plum Pudding Model." This model
was later found to be inaccurate. Thompson became the first person to separate isotopes of
the chemical element and in 1913 he found that neon had two forms (isotopes) differing
only in weight. During World War I he was active on the British Governments Board of
Research and Investigation and later he became the president of the Royal society. He also
became Master of Trinity College a post he held to his death.