Studied by 22 people
Describe the plum pudding model.
Atoms were spheres of positive charge with electrons stuck in them randomly
Describe Rutherford’s practical.
Fired alpha particles at thin gold foil, expecting them to pass straight through
What did Rutherford’s results show?
That most particles passed straight through, but some were deflected
What did Rutherford’s results demonstrate about the atom?
Atom had a small, positively charged nucleus in the centre but was mostly empty space
What the Bohr’s description of the atom?
Similar to Rutherford, but the electrons were fixed in electron shells
What is found in the electron shells?
Electrons
What charge do neutrons have?
Neutral
What charge do protons have?
Positive
What charge do electrons have?
Negative
What is the relative atomic mass of neutrons?
1
What is the relative atomic mass of protons?
1
If the atom gains electrons, what charge will it have?
Negative
If the atom loses electrons, what charge will it have?
Positive
What happens if an electron absorbs energy from EM radiation
It gets excited and can move up an energy cell
What happens when an atom emits EM radiation?
Electron falls back down an energy shell
What is an ion?
Atom that has lost an electron
What is ionising radiation?
Any radiation that can knock electrons from atoms
What is an isotope?
Atom with a different number of neutrons
What does the mass number show?
Number of protons + number of neutrons
What does atomic number show?
Number of protons
Which number is different in an isotope - mass or atomic?
Mass
What happens to unstable atoms?
Undergo radioactive decay
What is alpha radiation made up of?
2 protons and 2 neutrons
What can absorb alpha?
Skin/paper
Is alpha ionising?
Yes
What is beta+ radiation?
Positron
What is beta- radiation?
Electron
What is beta absorbed by?
Absorbed by aluminium
Is beta ionising?
Yes
What is gamma radiation made up of?
It is an EM wave
What can absorb gamma?
Thick lead
Is gamma ionising?
Yes
What happens to the mass number after alpha decay?
Mass number decreases by 4
What happens to the atomic number after alpha decay?
Decreases by 2
What happens to the mass number after beta+ decay?
Doesn’t change
What happens to the atomic number after beta+ decay?
Increases by 1
What happens to mass number after beta- decay?
Doesn’t change
What happens to the atomic number after beta- decay?
Increases by 1
What happens to the mass number after neutron emission?
Decreases by 1
What happens to the atomic number after neutron emission?
Doesn’t change
What happens to the mass number during gamma decay?
Doesn’t change
What happens to atomic number after gamma decay?
Doesn’t change
What is half life?
Time taken for the number of radioactive nuclei to halve
What is the activity of a source measured with?
Geiger-muller tube
What is activity measured in?
Becquerel’s (Bq)
What is irradiation?
Exposure to radiation but not radioactive
What is contamination?
Radiation gets into the body
Why is radiation dangerous?
Can damage DNA and then lead to cancer
What are the 2 types of waves?
Transverse and longitudinal
What do waves transfer?
Energy
What does amplitude mean?
Distance from the undisturbed position to the peak of a wave
What does crest mean?
Top of displacement
What does trough mean?
Bottom of displacement
What is frequency?
How many waves pass a fixed point in 1s
What is the period of a wave?
The number of seconds taken for 1 full cycle
How do transverse waves oscillate?
Perpendicular to the direction of travel
How do longitudinal waves oscillate?
Parallel to the direction of travel
What is frequency measured in?
Hertz (Hz)
What is wavelength measured in?
Metres (m)
What is wave speed measured in?
m/s
What is distance measured in?
Metres (m)
What is time measured in?
Seconds (s)
Give 3 transverse waves.
Radiowaves, microwaves, infrared
Give 2 longitudinal waves.
Sound waves, P waves
What 3 things can happen to waves at boundaries?
Absorbed, transmitted, or reflected
What is refraction?
When waves change direction at a boundary
Why does light change direction when entering a glass block at an angle?
Glass is more dense - light slows down
What is the normal?
Imaginary line perpendicular to where the wave hits the medium
What are the EM waves?
Radiowaves
Microwaves
Infrared
Visible light
UV
X-rays
Gamma
Which EM wave has the highest frequency?
Gamma
Name a use for radiowaves?
Communication
Name a use for microwaves?
Cooking
Name a use for infrared.
Remote controls
Name a use for visible light.
Photography
Name a use for UV?
Tanning
Name a use for x-rays.
Medicine
Name a use for gamma.
Treating cancer
Name a danger for radiowaves.
None
Name a danger for microwaves.
Burn
Name a danger for infrared.
Burn
Name a danger for visible light.
Damage eyes at high intensity
Name a danger for UV.
Skin cancer
Name a danger for x-rays.
Cancer
Name a danger for gamma.
Cancer
How are radiowaves made?
Through oscillating charges in a circuit
Why can light disperse when hitting a boundary?
Colours of light travel at different wave speeds
What is the order of colours in visible light?
Red
Orange
Yellow
Green
Blue
Indigo
Violet
List the energy stores.
Kinetic
Thermal
Chemical
Gravitational potential
Elastic potential
Electrostatic
Magnetic
Nuclear
What energy store is in moving objects?
Kinetic
Which energy store is released through nuclear reactions?
Nuclear
Which energy store is released through chemical reactions?
Chemical
Which energy store is in all objects - but hotter objects have more of it?
Thermal
What is energy measured in?
Joules (J)
What is mass measured in?
Kilograms (kg)
What is velocity measured in?
m/s
What is the gravitational field strength on Earth?
10 N/kg
What happens to the GPE as height increases?
Increases
What happens to GPE as an object falls?
Decreases
When an object hits the floor what happens to its KE?
Decreases
What does dissipate mean?
Transferred to the surroundings
Note 
Flashcard (85)