Rutherfords model of the Atom

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Rutherfords model of the Atom
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People in the group

• Jordan Neil

• Erin Isnor

• Heather Pickford

• Daniel Deines

• Leanne Myers

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Ernest Rutherford
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Ernest Rutherford1st Baron Rutherford of Nelson
and Cambridge(1871-1937)
Ernest Rutherford, British physicist, who became
a Nobel laureate for his pioneering work in
nuclear physics and for his theory of the
structure of the atom. Rutherford was born on
August 30, 1871, in Nelson, New Zealand, and was
educated at the University of New Zealand and the
University of Cambridge. He was professor of
physics at McGill University in Montréal, Quebec,
from 1898 to 1907 and at the University of
Manchester in England during the following 12
years. After 1919 he was professor of
experimental physics and director of the
Cavendish Laboratory at the University of
Cambridge and also held a professorship, after
1920, at the Royal Institution of Great Britain
in London.
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His famous experiment

• In 1911 Ernest Rutherford thought it would
  prove interesting to bombard atoms with alpha
  rays, figuring that this experiment could
  investigate the inside of the atom (sort of like
  a probe). He used Radium as the source of the
  alpha particles and shinned them onto the atoms
  in gold foil. Behind the foil sat a fluorescent
  screen for which he could observe the alpha
  particles impact.

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What was supposed to happen?
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• The results of the experiments came
  unexpected. Most of the alpha particles went
  smoothly through the foil. Only an occasional
  alpha veered sharply from its original path,
  sometimes bouncing straight back from the foil.
• Rutherford reasoned that they must get
  scattered by tiny bits of positively charged
  matter.
• Most of the space around these positive
  centers had nothing in them. He thought that the
  electrons must exist somewhere within this empty
  space.

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• Rutherford thought that the negative electrons
  orbited a positive center in a manner like the
  solar system where the planets orbit the sun.

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What does he know..

• Rutherford knew that atoms consist of a compact
  positively charged nucleus, around which
  circulate negative electrons at a relatively
  large distance.
• The nucleus occupies less than one thousand
  million millionth of the atomic volume, but
  contains almost all of the atom's mass. If an
  atom had the size of the earth, the nucleus would
  have the size of a football stadium.

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What Confronted Rutherford?

• Ernest Rutherford had been studying alpha
  particles since 1898. In fact, he discovered
  them.
• To him, alpha particles were part of the family.
  In 1909 he was confronted with some rather
  bizarre alpha-particle behavior that he had to
  explain. What was the behavior, exactly?

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• Hans Geiger and Ernest Marsden aimed a stream of
  alpha particles at a thin gold foil for several
  months in 1909. (They would continue studying
  scattering until 1913.) Geiger cites a thickness
  of 8.6 x 106 cm. for the foil. In fact, the foil
  was so thin that it had to be supported on a
  glass plate. (The plate without any foil was
  studied and no deflections were found. It was
  transparent to the alpha particles.) There were
  three major findings

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