nuclear binding energy equation
E = mc^2
mass deficit equation
mass before - mass after
what is the binding energy
the energy required to separate the nucleus into its nucleons
define one atomic mass unit
1/12th of the mass of a carbon-12 atom
how much energy is released when there is a change in mass of 1u
931.5 MeV
nuclear fusion
the joining of two small nuclei to form a larger nucleus
is energy released or absorbed in nuclear fusion
energy is released because the larger nucleus has a higher binding energy per nucleon
nuclear fission
a larger nucleus splits to form two smaller daughter nuclei - occurs in very unstable nuclei e.g U-235
is energy released or absorbed in nuclear fission
energy is released because the smaller nuclei have a higher binding energy per nucleon
what releases more energy - fission or fusion?
fusion
binding energy per nucleon curve - fision and fusion?
fusion - can occur between elements up to Fe-56
fission - can occur between elements after Fe-56 up to U-235 / U-235
conditions required for nuclear fusion to occur
- extremely high temperatures
- high densities of matter
why are high temperatures needed?
massive amount of energy is required to overcome the electrostatic force of repulsion between the nuclei
why are high densities needed?
- in order to maintain fusion
- so that there are enough colliding protons undergoing fusion
alpha radiation
- nature
- range in air
- penetration
- ionising ability
- 2 protons & 2 neutrons
- 2-10 cm
- absorbed by paper
- highly ionising
beta radiation
- nature
- range in air
- penetration
- ionising ability
- fast moving electron
- ~1m
- aluminium foil
- weakly
gamma radiation
- nature
- range in air
- penetration
- ionising ability
- E.M. wave
- infinite range
- several metres of concrete/lead
- very weakly
alpha decay
- proton number decreases by 2
- nucleon number decays by 4
beta-minus decay
- proton number decreases by 1
- nucleon number stays the same
radioactive decay
a random and spontaneous process
