Early Models of the Atom
An important observation
Some students are inclined to say "just tell use the facts as we know them today, this is not a history course". I am not interested in relatively ancient and disproven theories.
The problem with this approach, however, is that it ignores the creative aspect of science and how we progress through trial and error, through model creation, modification, or rejection, etc. It gives a false impression of how science develops.
More importantly, however, it is not possible to understand today's view of the atom without insight into the concepts that led to it.
|
J. J. Thompson's
Plum Pudding Model
The plum pudding model
of the
atom
was proposed in 1904 before the discovery of the atomic nucleus.
In this model, the atom is composed of electrons (which Thomson
still called "corpuscles", surrounded by a soup of positive charge
to balance the electron's negative charge, like negatively-charged "plums"
surrounded by positively-charged "pudding".
Ernest Rutherford's model of the atom (Far right)
Electrons orbit a tiny positive nucleus.
The atom is visualized as mostly empty space.
Rationale for both models
Based on observations and interpretation of those observations at the time |
 |
 |