P5 nuclear physics Flashcards
describe the composition of the nucleus
protons and neutrons
relative charge of protons
+1
relative charge of neutrons
0
relative charge of electrons
-1
define proton number
number of protons found in the nucleus
define nucleon number
total number of protons and neutrons found in the nucleus
relationship between proton number and relative charge on nucleus
proton number equal to relative charge of nucleus
nuclide notation
A: proton number
Z: nucleon number
describe the process of nuclear fission
- due to instability, heavy nuclei split apart
- into daughter nuclei
- energy released
describe the process of nuclear fusion
- nuclei collide with high energy
- join to form larger nucleus
- energy released
are some isotopes radioactive?
yes
what is meant by ionising nuclear radiation
- carry enough energy to strip away electrons from atoms
- leave behind ions
- can be very harmful to living things and damage electronics
what is meant by background radiation
- exists around us all the time
significant sources of background radiation
- radon gas (in the air)
- rocks and buildings
- food and drink
- cosmic rays
how can ionising nuclear radiation be measured
- using detector (geiger-müller tube)
- connected to a counter
- counts/s or counts/minute
nature of alpha (α) emissions
- 2 protons
- 2 neutrons
relative ionising effects of alpha emissions and why
- due to large mass and charge
- highly ionising
relative penetrating abilities of alpha emissions
- least penetrating
- 5cm through air
- stopped by materials eg thin paper, skin
nature of beta emissions
- high energy electron
relative ionising effects of beta emissions
- lower charge of -1
- so only mildly ionising
relative penetrating abilities of beta emissions
- can travel thru skin
- stopped by few mm of aluminium foil
nature of gamma emissions
- EM waves
- high frequency
- high energy
relative ionising effects of gamma emissions
- no mass, no charge
- weakly ionising
relative penetrating abilities of gamma emissions
- most penetrating
- only be stopped by thick lead of concrete
what is radioactive decay
- change in unstable nucleus
- can result in emission of α-particles or β-particles and/or γ-radiation
- changes are spontaneous and random
in which radiation does nucleus change
α-decay or β-decay
- changes to that of diff element
change in nucleus that occurs during β-emission
decay equation for emissions of α-particles
decay equation for emission of β-particles
decay equations for emission of γ-particles
define half-life
- time taken for half the nuclei
- of that isotope in any sample to decay
applications of radioactivity
- household fire (smoke) alarms
- irradiating food to kill bacteria
- sterilisation of equipment using gamma rays
- measuring and controlling thicknesses of materials
- diagnosis and treatment of cancer using gamma rays
effects of ionising nuclear radiation on living things
- cell death
- mutations
- cancer
safety strategies for radioactivity
- limit exposure time to reduce experience of emissions
- shielding. placing barrier between
- increase distance from radioactive source, reduce intensity of radiation
