Elements of Life: Atomic Models
- Created by: Frankey
- Created on: 28-12-10 09:30
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The Accepted Model of the Atom Has Changed Throughout History
- Ancient Greeks: all matter was made from indivisible particles
- C19th John Dalton: solid spheres, different spheres made up different elements
Experimental Evidence Showed that Atoms Weren't Solid Spheres
- 1897: J. J. Thompson concluded atoms weren't solid and indivisible
- measurements of charge and mass showed that an atom must contain smaller negatively charged particles: electrons
- plum pudding model
Rutherford Showed that the Plum Pudding Model Was Wrong
- 1909: Ernest Rutherford and students Hans Geiger and Ernest Marsden
- gold foil experiment
- fired alpha particles at gold sheet
- expected most alpha particles to be deflected very slightly by positive "pudding"
- most alpha particles actually passed straight through gold atoms
- very few deflected backwards
- this showed plum pudding model couldn't be right
- came up with nuclear model
- tiny, positively charged nucleus at centre
- most of atoms mass
- surrounded by a "cloud" of negative electrons
- most of the atom is empty space
- tiny, positively charged nucleus at centre
- gold foil experiment
Rutherford's Nuclear Model was Modified Several Times
- Henry Moseley: charge of nucleaus increased from one element to…
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