nuclear Flashcards
what was observed in the Rutherford alpha scattering experiment
most of the alpha particles passed straight through the foil
and very few particles were deflected by angles larger than 90 degrees
what did most of the alpha particles passing through the foil indicate
nucleus is mostly empty space with most of the mass concentrated in a small region
what does the angles being reflected more than 90 degrees indicate
the nucleus has a positive charge which was repelling the alpha particles
how do estimate the size of the nucleus
equate the initial kinetic energy of the alpha particle to the electrical potential energy
r=Qq/4πƐ0(KE)
what is the equation for electrical potential energy
Qq/4πƐ0r
what does A. stand for next to chemical element
the nucleon number number of protons and nuetrons
what does z stand for
the proton number the number of protons
what is the equation for nuclear size
R = r0A^1/3
where R is the radius
r0 is a constant
and A is A is the nucleon number
how do you work out the density of the nucleus
d=m/v
d=m/(4/3)πR^3
d=m/(4/3)π(r0A^1/3)^3
d=m/(4/3)π(r0A)
why is the nuclear density independent of the nucleon number
mass =kA
and so A cancels out in d=kA/(4/3)π(r0A)
what is true about the strong nuclear force
acts on all nucleons
short ranged force
attractive up to 3fm
and repulsive believe 0.3 fm
what does every particle have
every particle has a corresponding antiparticle
what is true about antiparticles and corresponding particles
have the same rest mass
and opposite charge
what does the gravitational force act on
all objects with mass
what does the electromagnetic force act on
all particles with charge
what is the weak nuclear force responsible for
beta plus and beta minus
what force are hadrons affected by
the strong nuclear force
what force are leptons not affected by
strong nuclear force
what is the activity of a radioactive source
the rate of decay of. radioactive source
unit for activity
Bq becquerel
equation for activity
A=ΔN/Δt
what is the decay constant
probability of decay of a single nucleus
what are the units of decay constant
s^-1
what is the equation of activity involving the decay constant
A=λN
what happens to activity and the number of particles against time
decay exponentially against time
write the exponential equations of activity and number of particles
A=A0e^-λt
N=N0e^-λt
what is Δm equal to
Δm=mfinal - m initial
what is Einsteins famous energy equation
E=Δmc²
what is binding energy
energy require to completely separate a nucleus into its constituents
what is the mass defect
the difference between the mass of a completely separated nucleus and the nucleus itself
what is the binding energy per nucleon
minimum energy required to remove a nucleon from the nucleus
how do you work out the binding energy per nucleon
use E=Δmc²
where m is the mass defect
and then divide the energy by the number of nucleons
what is nuclear fusion
when two lighter nuclei combine to produce a heavy nucleus
what is nuclear fission
when a heavy nucleus splits into two lighter nuclei
for the binding energy per nucleon graph against nucleon number what is the most stable element
iron 56
for the binding energy per nucleon against nucleon number what is true about elements to the right of iron 56
there’s fission taking place
for the binding energy per nucleon against nucleon number what is true about elements to the left of iron 56
there’s fusion taking place
what happens in a induce nuclear fission chain reaction
a single thermal neutron is absorbed by a nucleus creating a heavier unstable nucleus which undergoes fission and its split into two nuclei and more nuetrons
what do fuel rods
contain uranium fuel
what do control rods
absorb some of the neutrons to condo the rate of the nuclear reaction
what does the moderator o
slows down the fast moving neutrons to create thermal neutrons
what do you need for nuclear fusion to take place
high temperature and high pressure for the nuclei to overcome the electrostatic repulsion
what Is carbon dating used for
used to estimate the age of dead living organisms
out of carbon 12 and carbon 14 which is radioactive
carbon 12 stable carbon 14 radioactive
how is carbon 14 produced
continuously produced in the atmosphere by cosmic rays
what happens once a living organism dies
it stops absorbing carbon and so the carbon 14 continues to decay
what is true about the ratio of carbon 12 to carbon 14 in all living things
it is constant
what is the half life equation
t(1/2)=ln2/λ
what does technetium 99 produce
releases gamma radiation
what is technetium 99m used for
medical tracer which is injected into the blood stream absorbed by organs bones and muscles when technetium 99m decays releases gamma radiation gamma radiation travels at the speed of light through bones muscles and organs a gamma camera can detect the technetium
what are the advantages of technetium 99m
big enough half life to allow for absorption of organs muscles and bones half life is short enough so overall radiation is low and not harmful
