atomic physics Flashcards
nuclear fission
is the splitting of atomic nuclei
- carried out in a nuclear reactor
- uranium - 235 used as fuel
nuclear fusion
joining of two nuclei
advantages
- fuel needed readily available as heavy hydrogen (found in sea water)
- product formed is helium which is harmless
- energy released could be used to generate electricity
where does nuclear fusion occur naturally?
in the stars (e.g the sun)
why does nuclear fusion require so much energy
nuclei are both positively charged and therefore repel
sources of background radiation
- cosmic rays
- food
- xrays
- rocks
ionizing radiation
random process
- either alpha, beta or gamma is given off
alpha decay
2 neutrons and 2 protons are emitted
- mass number decreases by 4
- atomic number decreases by 2
beta decay
neutrons turns into a proton and stays in the nucleus of an atom
- an electron is emitted
- mass number unchanged
- proton number increase by 1 so new element
gamma radiation
an electro magnetic wave
no changes
least and most ionizing
alpha - most ionizing
gamma - least ionizing
penetrating power
alpha - stopped by paper or a few cm of air
beta - stopped by aluminum foil
gamma - stopped by several cm of lead
range in air
alpha - 5-10 cm
beta - few cm
gamma - indefinite number
gamma
emitted after the emission of alpha or beta
EM wave - no mass no protons no neutrons
detected by - Geiger muller tube
how to detect alpha
cloud chamber
- contains cold alcohol vapor in air
- visible trails of condensed alcohol
nature of radioactive emission
happens spontaneously and at random
- can’t predict decay or direction
- unaffected by - changes in temp and pressure
