Sir James Chadwick

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Sir James Chadwick
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Beginning Life

• Born in Cheshire, England
• Born on 20, October, 1891
• Son of Joseph Chadwick
• Mother Anne Mary Knowles
• Attended Manchester High School in 1908
• He Graduated from the honors school of Physics in
  1911
• Spent 2 years with Professor Rutherford

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Life after college

• He worked in the physical liberators in
  Winchester on various radioactive problems.
• Gained Masters degree in 1913
• Worked with Physikalisch Technische Reichsanstalt
  at Charlottenburg under professor H. Geiger in
  Berlin, Germany

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Contributions

• In Cambridge, Chadwick worked with Rutherford in
  accomplishing the transmutation of other light
  elements by bombardment with alpha particles and
  in making studies of the properties and structure
  of atomic nuclei.

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Discovery of the neutron

• In 1932, Chadwick discovered the neutron.
• Neutrons do not have any electrical charge.
• He then knew that the nucleus has both protons
  and neutrons (see picture).

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Beryllium Experiment

• In 1932 Chadwick observed that beryllium, when
  exposed to bombardment by alpha particles,
  released an unknown radiation that in turn
  ejected protons from the nuclei of various
  substances.
• Chadwick interpreted this radiation as being
  composed of particles of mass approximately equal
  to that of the proton.
• These newly discovered particles were neutrons.
•  

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Summary

• (1891-1974)
• Sir James Chadwick
• Discovered the neutron in 1932
• Neutrons have approximately the same mass as
  protons
• Neutrons have no electric charge