P4 Atomic Structure Flashcards
what is alpha radiation
when an alpha particle is emmited from the nucleus. they consist of two neutons and two protons
they do not penetrate very far into materials snd are stopped quickly - they can only travel a few cm in air and can be absorbed by a sheet of paper
they are strongly ionising
what is beta radiation
beta particles are high speed electrons released by a nucleus. beta particles have no mass and a charge of - 1
they are moderately ionising
they are moderately penetrating
they have a range in air of a few metres and can be absorbed by a sheet of aluminium
for every beta particle emitted a neutron in the nucleus has turned into a proton
what is gamma radiation
gamma rays are electromagnetic waves with a short wavelength. they are released by the nucleus. they penetrate far into materials without being stopped and will travel a long distance through air.
they are weakly ionising because they tend to pass through rather than collide with atoms
they can be absorbed by thick sheets of leaf or metres of concrete
what is half life
the time taken for the number of radioactive nuclei in an isotope to decay or decrease by half
what is nuclear fission
a type of nuclear reaction that is used to release energy from large and unstable atoms by splitting them into smaller atoms
what is a chain reaction
when slow moving neutrons are absorbed by another nucleus causing more fission to occur
how is the amount of energy produced by fission controlled
by changing how quickly the chain reaction can occur. this is done using control rods which absorb neurons and slows down the reaction
what is nuclear fusion
the opposite of nuclear fission, two light nuclei collide at high speed and join to create a larger heavier nucleus.
describe the mass of a nucleus created during nuclear fusion
the new nucleus does not have as much mass as the two separate nuclei did. this is because some of the mass is converted to energy
what is contamination
when unwanted radioactive atoms get onto or into an object it is said to be contaminated
