What are they called when some atoms of the same element can have different numbers of neutrons?
isotopes
2 of 33
What are the three types of ionising radiation?
Alpha, Beta, Gamma
3 of 33
How far is alpha absorbed?
a few centimeters of air or a thin sheet of paper
4 of 33
How far is Beta absorbed?
passes through air and paper but is absorbed by a few meters of aluminium
5 of 33
How far is gamma absorbed?
very penetrating and needs many centimeters of lead or many meters of concrete to absorb most of it
6 of 33
What is emmited when the nucleus of an unstable atom decays?
ionising radiation
7 of 33
What does the type of radioactive decay depend on?
why the nucleus is unstable
8 of 33
What happens during alpha decay?
original atom decays by ejecting helium alpha particle from nucleus, made from 2 protons & neutrons, a new atom is formed with 2 less protons & neutrons than the original
9 of 33
What happens during beta decay?
original atom decays by changing a neutron into a electron and proton, high energy electron now ejected from nucleus as a beta particle, a new atom is formed with one less proton and neutron than the original
10 of 33
What happens during gamma decay?
after alpha or beta, a nucleus sometimes contains surplus energy, it emits this as gamma radiation, only energy is emitted, doesn't change the type of atom
11 of 33
What does it mean when a person is irradiated?
they're exposed to radiation
12 of 33
What does it mean when a person is contaminated?
radioactive material is on their skin, clothes, or has entered their body
13 of 33
What is the half life of a substance?
the time it takes for its radioactivity to halve
14 of 33
When is a radioactive substance considered safe?
when its activity drops to the same level as background radiation
15 of 33
What is considered a safe amount of radiation?
3 millisieverts a year
16 of 33
What is the sievert?
the measure of a radiation dose's potential harm to a person
17 of 33
Why is alpha the most dangerous inside the body?
all the radiation will be absorbed by cells in the body
18 of 33
Why is beta the most dangerous outside the body?
it can penetrate the outer layer of skin and damage internal organs
19 of 33
How can gamma cause harm?
absorbed into cells, weakly ionising and can pass straight through the body causing no damage at all
20 of 33
What can radiation be useful for?
killing cancer cells, sterilising surgical instruments and food, as a tracer in the body
21 of 33
How does a PET scan work?
radio-labelled glucose put in blood stream, gamma rays let out and picked up to create body image
22 of 33
What is high-level waste? (HLW)
very radioactive waste that has to be stored carefully
23 of 33
What is intermediate-level waste? (ILW)
not as radioactive as HLW but remains reactive for thousands of years, mixed with concrete and stored in containers
24 of 33
What is low-level waste? (LLW)
only slightly radioactive waste that is sealed and placed in landfills
25 of 33
Where does nuclear fission take place?
in the nucleus of the atom
26 of 33
What are formed during nuclear fission?
new elements
27 of 33
How does nucleur fission work?
nutron absorbed by large and unstable uranium nucleus, splits in 2, releases energy and more neutrons,
28 of 33
What does nuclear fission cause to happen?
chain reaction
29 of 33
What controls the chain reaction so that energy is steadily released in a nuclear power station?
nuclear reactor
30 of 33
What three observations were made in the alpha particle scattering experiment?
most alpha particles were seen to pass straight through the gold foil, some particles were deflected slightly, a few particles bounced back towards the source
31 of 33
What 3 conclusions were made in the alpha particle scattering experiment?
atoms consist largely of empty space with a small dense core-the nucleus, the nucleus is positively charged, the electrons are arranged around the nucleus with lots of space between them
32 of 33
What does the strong nuclear force within a nuceus balance?
the repulsive electrostatic force between the protons
33 of 33
Other cards in this set
Card 2
Front
What are they called when some atoms of the same element can have different numbers of neutrons?
Comments
No comments have yet been made