Transcript Discovery of electron

Discovery of electron
• 1897 - J.J. Thomson (1856-1940)
http://www.chemheritage.org/classroom/chemach/atomic
/thomson.html
http://www.aip.org/history/electron/
(Kennedy, Chemistry Live!)
Mass spectrometry
• Sample converted to positive ions by collisions
with a stream of high energy electrons on
entering the spectrometer.
• Charged sample is accelerated using applied
voltage
• Ions then passed into an evacuated tube and
through a magnetic field.
• Magnetic field causes ions to be deflected by
different amounts depending on their mass.
• Ions with the same mass-to-charge ratio hit the
detector at the same spot.
(Brown, LeMay and Bursten, 9th ed., p.45)
Determination of electron charge
Robert Millikan (1868 – 1953)
Discovery of nucleus
• 1911 - Ernest Rutherford (1871-1937)
Quantum Theory and the Atom
• Niels Bohr (1885 – 1962)
http://www.pa.msu.edu/~brock/d0_homepage/physicsposted/surprises-bohr.html
http://www.pbs.org/wgbh/aso/databank/entries/dp13at.html