6.4.1.3 The Development of the Model of the Atom Flashcards
1
Q
What were atoms thought to be before the discovery of the electron?
A
- tiny spheres that cannot be divided
2
Q
What did the discovery of the electron lead to?
A
- plum pudding model
3
Q
Who discovered the plum pudding model in 1897?
A
- J.J. Thomson
4
Q
What did the plum pudding model suggest?
A
- atoms were spheres of positive charge
- with negative electrons embedded in them
5
Q
Who discovered the alpha scattering experiment in 1909?
A
- Rutherford
6
Q
What was the alpha scattering experiment?
A
- firing a beam of alpha particles at thin gold foil
- expected particles to go straight through but some were deflected more than expected, others completely
7
Q
What did the alpha scattering experiment lead to?
A
- realisation that mass of an atom is concentrated at the centre (nucleus)
- nucleus is charged
- nuclear model
8
Q
Who discovered the Bohr model in 1913?
A
- Niels Bohr
9
Q
What did Niels Bohr suggest?
A
- electrons orbit nucleus at specific distances (different energy levels)
- discovery of the proton: positive charge of any nucleus subdivided into these
10
Q
What did James Simpson discover in 1933?
A
- neutron within nucleus
- explained imbalance between atomic and mass numbers
