What is the Structure of the Atom?

1
What is the Structure of the Atom?

• Over 2,400 years ago, Greek philosophers
  understood that matter must consist of a small,
  single unit.
• The Greeks called the basic unit of matter,
  atomos meaning indivisible or cannot be broken
  smaller.
• We must look back in history to scientists quest
  for knowledge and understanding.

2
Early Discoveries

• Scientists That Studied the Structure of the
  Atom
• Dalton
• Crookes
• Thomsom
• Becquerel
• Rutherford
• Chadwick
• Niels Bohr

3
John Dalton

• In 1802, John Dalton, a British chemist,
  developed the first model of the atom.
• Daltons atom was a solid, indivisible particle.
• Developed the first atomic theory.

4
William Crookes

• British physicist.
• In the late 1800s, created a vacuum tube with a
  positive and negative terminal.
• This tube, later known as a cathode ray tube, was
  used for experiments.

5
J. J. Thompson

• Experimented with Crookess vacuum tube.
• Observed the beam of particles bent in the
  presence of an electric field.
• Showed the particles had less mass than an atom.
• Received the Nobel Prize in 1906 for his
  discovery of the electron.
• Thompsons model of the atom resembled a
  blueberry muffin.

6
Henri Becquerel

• Accidentally discovered radiation from a sample
  of uranium left on a photographic plate.
• Discovered that atoms of uranium give off
  negatively charged particles evidence that atoms
  were made up of smaller particles.
• In 1896, Becquerel received the Nobel Prize for
  the discovery of radiation.

7
Ernest Rutherford

• After Becquerels discovery of radiation,
  Rutherford further studied individual particles
  alpha, beta and the gamma ray.
• His studies gave science more information about
  the atom and even more questions.
• In 1908, Rutherford won the Nobel Prize in
  chemistry concluding the atom had a positively
  charged nucleus and an electron orbiting.

8
James Chadwick

• In 1932, Chadwick, a student of Rutherfords,
  studied radiation from beryllium.
• His particle was not affected by an electric
  field, therefore it must have had a neutral
  charge.
• In 1935, Chadwick won the Nobel Prize for his
  discovery of the neutron.

9
Niels Bohr

• 1885 1962
• 1911 Worked under Sir J.J. Thomson in
• Cambridge England
• 1912 Worked in Rutherfords Laboratory in
  Manchester England
• Professor of Theoretical Physics at Copenhagen
  University
• Researched the nucleus of the atom Neutron
  Capture
• Developed the Electron Cloud model of the atom