Chapter 1&2- History of the Atom Flashcards
1
Q
Summarise Dalton’s Atomic Theory
A
- All matter is made up of very small particles called atoms.
- All atoms are indivisible therefore cannot be broken down.
2
Q
Define “Cathode ray”
A
Cathode rays are streams of electrons that travel in straight lines from the cathode to the anode.
3
Q
Who supposedly discovered the electron
A
J.J Thompson
4
Q
Define the “Law of Conservation of Mass”
A
energy cannot be created nor destroyed only changed from 1 form to another.
5
Q
Explain Thomson’s Plum Pudding Model
A
- knew majority of mass was positively charged
- positive spheres in which negatively charged electrons are embedded
6
Q
Explain Millikan’s oil drop experiment
A
- voltage applied to fine mist of electrically charged oil drops - causes upward force
- adjusted until it balances gravity
- charge on electron measured accurately
7
Q
Who discovered the nucleus, and the proton of an atom?
A
Rutherford
8
Q
Explain Rutherford’s Gold Foil Experiment
A
- Geiger & Marsden
- fire α-particles at thin gold foil
- large no. not deflected - essentially empty space
- many deflected at small angles
- some deflected at large angles
- few rebounded
The mostly empty space, small dense nucleus at centre, electrons moving around to balance the charge
9
Q
Who discovered the neutron?
A
James Chadwick
