atomic structure
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40 Terms
what is an isotope?
atoms of the same element with different number of neutrons
what is radioactivity?
random emissions of radiation from unstable nuclei
what is forces measured in?
newtons (N)
what is friction?
force that opposes motion between surfaces
air resistance
type of friction that acts against moving objects in the air
speed
speed=distance÷time
weight=
weight=mass X gravitational field strength
current
current= charge ÷ time
potential difference
potential difference = current x resistance
power
power = energy transferred ÷ time
3 types of nuclear radiation
alpha
gamma
beta
what is an alpha particle?
two protons
two neutrons
what charge does alpha radiation have?
+2 positive
how far can alpha travel in the air?
few centimetres
what can stop alpha radiation?
paper or skin
what is a beta particle?
a fast moving electron
what charge does a beta particle have?
-1 negative
what can stop beta radiation?
thin aluminium
what is gamma radiation?
high-energy electromagnetic waves
does gamma radiation have a mass?
no
does gamma radiation have a charge?
no
what can stop gamma radiation?
thick lead
concrete
which type of radiation is the most ionising?
alpha
which type of radiation is the most penetrating?
gamma
which type travels furthest in the air?
gamma
what is a half life?
the time it takes for half the radioactive nuclei in a sample to decay
does radioactivity ever completely stop?
no but it becomes very small over time
give one use of alpha radiation
smoke detectors
give one use of beta radiation?
measuring the thickness of paper or aluminium
give one use of gamma radiation
sterilising medical equipment or treating cancer (radio therapy)
why is radiation dangerous?
damages our cells and DNA
increases risk of cancer
how can you reduce the exposure to radiation?
spend less time near the source
use shielding
what is irradiation?
when an object is exposed to radiation
does irradiation make the object radioactive?
no once the radiation source is removed the object is usually not radioactive
what is contamination?
when radioactive material gets onto or inside an object
does contamination make an object radioactive?
yes the radioactive material continues to emit radiation until it is removed or decays