Models Of Atoms Flashcards
With dates and names, put in order the discoveries of the atom
1803 - John Dalton (atoms were solid spheres)
1897 - J J Thomson (discovered electrons)
1909 - 1911 - Ernest Rutherford (discovered positive nucleus)
1913 - Neils Bohr (discovered shells)
1932 - Edwin Chadwick (discovered neutrons)
What did John Dalton suggest?
That atoms were solid spheres of matter that could not be split, and that each element contained identical atoms (uncharged)
What did J J Thomson suggest?
That the atom was a positively charged sphere with negative electrons distributed throughout it (Plum Pudding Model)
How did J J Thomson discover electrons?
He demonstrated that cathode rays were negatively charged, and discovered negative particles were given out by atoms and were much smaller than the atoms
What was Ernest Rutherford’s model called, and what did it show?
Nuclear model - suggested the atom was mostly empty space with a positive tiny central nucleus that contained most of its mass. Electrons orbited around the outside (NOT in shells)
Describe Rutherford’s experiment, with results
- fired positively charged alpha particles at thin gold foil in a vacuum
- most went straight through foil without any deflection, few were scattered in different directions, and 1/20000 were reflected back
What did the results of Rutherford’s experiment mean?
As only 1/20000 were reflected back, it meant that only a small section of the atom was positive
What did Bohr discover, and what with?
With calculations he suggested:
- that electrons orbit the nucleus at certain distances from the nucleus in shells
With further experiments he suggested:
- that the nucleus contained small particles called protons
Whose atomic model is still used today?
James Chadwick’s
What did James Chadwick find evidence for in 1932?
For the existence of particles in the nucleus with mass, but no charge (neutron)
