NUCLEAR PHYSICS Flashcards
1
Q
who created the plum pudding model
A
- J.J. Thomson in 1904
2
Q
how does the plum pudding model work
A
- the positive charge and most of the atom’s mass is evenly distributed across the whole atom
- negatively charged electrons are dotted throughout like raisins, or plums, in a pudding
3
Q
what did Rutherford scattering demonstrate
A
- the existence of a nucleus
4
Q
how did Rutherford scattering work
A
- narrow beam of alpha particles aimed at a thin piece of gold foil, measured their angle of deflection using a microscope
5
Q
what were the results found with rutherford scattering
A
- most alpha particles passed straight through with no deflection, suggesting most of the atom was empty space
- a small number of alpha particles were deflected by a large angle, and some even bounced back, which suggested that the atom’s mass and positive charge were concentrated in a small region
6
Q
why does the rutherford scattering oppose plum pudding model
A
- if the plum pudding model was true, the particles would be deflected by a very small amount when passing through, however this was not the case
- large angle deflection occured
7
Q
how small is the radius of a nucleus
A
- 10,000 times smaller than radius of an atom
8
Q
what is radiation?
A
- where an unstable nuclei emits energy in the form of EM waves or subatomic particles in order to become stable
9
Q
what the ionising level of alpha radiation?
A
- very strongly ionising
10
Q
is alpha radiation deflected in a magnetic field?
A
- yes
11
Q
what is alpha radiation absorbed by?
A
- paper
12
Q
how can we measure the amount of ionising radiation?
A
- using a Geiger Tube
13
Q
how does a Geiger Tube work
A
- when ionising radiation enters the tube, it creates free charges, which are attracted to the electrodes
- this generates a pulse of charge, measured as counts
14
Q
what is meant by count rate?
A
- numher of counts measured per second / minue
15
Q
what happens if theres no radioactive source present inside the tube?
A
- we still measure a count rate due to background radiation
