p6 Flashcards
2 ways that an atoms electron arrangement can be changed
Absorbing EM radiation
Emitting EM radiation
Explain how an atoms electron arrangement changes when it absorbs em radiation
Electrons move further away from nucleus
Higher energy level
Explain how an atoms electron arrangement changes when it emits em radiation
Electrons move closer to nucleus
Move to lower energy level
Why do unstable nuclei give out radiation
They undergo decay to become more stable
As they release radiation their stability increases
What is radioactive decay
Process in which an unstable nucleus gives out radiation to become more stable
State 4 types of nuclear radiation
Alpha
Beta
Gamma
Neutrons
Give equation for an alpha particle
a42
Range of alpha particle thru air
Few centimetres
What will stop beta radiation from passing thru a point
Thin sheet of aluminium
Several meters of air
Equation for beta particle
B0-1
What will stop gamma radiation from passing thru a point
Several cm of lead
Few metres of concrete
Equation for gamma radiation
Y00 (em wave)
Radiation types from most ionising to least
Alpha
Beta
Gamma
What changes to mass or charge occur due to emission of a gamma ray
Both mass and charge remain unchanged
Describe the nature of radioactive decay
Random
Which nuclei decays and when it does is determined only by chance
It is impossible to predict which nuclei will decay and when
Describe half life of radioactive isotope
Time taken for number of unstable nuclei in a substance to halve
Time taken for the count rate from a sample to call to half its initial level
Radiation types in order of most penetrating to least
Gamma, beta, alpha
What is radioactive contamination
Presence of unwanted radioactive nuclei on other materials
What is irradiation
Process of exposing a material to nuclear radiation
The material does not become radioactive
Give 3 practices applications of radioactive materials
Medical tracers
Radiotherapy
Smoke alarms
What kind of radiation is used in smoke alarms
Alpha
How do smoke alarms work
Alpha radiation emitted into air, reaching a detector and completing the circuit
If smoke is present, it blocks alphas radiation so it doesn’t reach the detector and the circuit is broken
Causing an alarm to sound
Give a use of beta emitters
Thickness monitoring of paper
How does thickness monitoring work
A source and receiver are placed on either side of the sheet
If there is a drop in rise in the no. of particles detected, the thickness has changed and needs adjusting
Why are isotopes with long half lives particularly harmful
They remain radioactive for much longer periods of time
Must be stored in specific ways to avoid humans and the environment from being exposed to radiation for too long
State 2 uses of nuclear radiation in the field of medicine
Examining internal organs
Controlling and destroying unwanted tissue
How is radiation used in sterilisation
Gamma emitters are used to kill bacteria/parasites on equipment
What kind of radiation is used for radiotherapy
Gamma
Explain the process of radiotherapy
Gamma emitters direct gamma rays onto specific areas with cancerous cells
The cells absorb the radiation and die
What are the risks of ionising radiation to ppl
It can damage living cells, causing them to die or mutate and become cancerous
What is nuclear fusion
Joining of 2 light nuclei to produce a heavier nuclei and release energy
Name 2 isotopes of hydrogen which are commonly used in nuclear fusion
Deuterium and tritium
Which releases more energy, nuclear fission or fusion
Fusion
Explain the difficulty of generating energy through nuclear fusion
Fusion requires very high temps which in itself required large quantities of energy and also requires casing which can withstand them
What can mass be converted into
Energy
What is nuclear fission
Splitting of large unstable nuclei to form smaller more stable nuclei (emission of spare neutrons)
What usually needs to happen to induced fission
Unstable nuclei must absorb a neutron
Spontaneous fission (where no neutron absorption occurs) is rare
Alongside 2 smaller nuclei, what else is emitted in a fission reaction
2 or 3 neturons
Gamma rays
Energy
What takes place during a chain reaction in a nuclear reactor
Unstable nuclei absorbs a neutron
Nucleus undergoes fission and releases 2 or 3 further neturons
These induce more fission, which results in a chain reaction
Which radiation is most damaging inside and outside the body
Inside- alpha
Outside- gamma
