Unit 2 2.1 – History of the Atomic Model. Atomic Structure .
Thomson's Atomic Model
Transcript of Thomson's Atomic Model
J. J. Thomson Joseph John Thomson December 18, 1856 – August 30, 1940 English physicist Served as the President of the Royal
Society in England from 1915 – 1920 He served as the adviser or teacher of
other scientists such as Ernest Rutherford, Niels Bohr, J. Robert Oppenheimer, etc.
J. J. Thomson Published “Treatise on the motion of
vortex rings” that showed Thomson’s interest on atomic theory
Discovery of the electron Discovery of the isotopes of
elements Discovered the natural radioactivity
of potassium
Cathode Ray Tube
Plum-Pudding Model
Plum-Pudding Model The atomic model proposed by J. J.
Thomson in 1904 Atoms were known to consist of
negatively charged electrons Atoms were neutrally charged The negative electrons occupied a
region of space that itself was a uniform positive charge (often considered as a kind of "soup" or "cloud" of positive charge).
Plum-Pudding Model Thomson proposed that the shape of an
atom resembles that of a sphere having a radius of the order of 10-10 m.
The plum pudding atomic theory assumed that the mass of an atom is uniformly distributed all over the atom.
The plum pudding atomic model was insufficient to explain the structure of an atom.