topic 4 Flashcards
why is ionising radiation dangerous
because it can enter living cells and cells and ionise atoms within them, meaning that it can damage cells and cause cancer or just kill cells of completely
what is exposure to radiation called
irradiation
3 ways to limit the source of radiation
- keeping sources in lead-lined boxes
- standing behind barriers when using sources
- standing in another room
what is contamination
unwanted radioactive particles getting onto objects
what 3 things can be used when handling objects with radiation
tongs, gloves and protective suits
why are beta and gamma rays the most dangerous
because they can penetrate the body and get to the delicate organs
how is alpha less dangerous than beta or gamma
because it can’t penetrate the skin and is easily blocked by a small air gap
how are alpha sources the most dangerous inside the body
because they do all their damage in a very localised area
how are beta sources less damaging inside the body
as radiation is absorbed over a wider area and some passes out of the body altogether
how are gamma sources the least dangerous inside our bodies
as they mostly pass straight out- they have the lowest ionising power
what did JJ Thompson discover
electrons
what did jj thompson suggest
that atoms were spheres of positive charge with tiny negative electrons stuck in them like fruit in a plum pudding (plum pudding model)
what did Rutherford do
fire a beam of alpha particles at thin gold foil- the alpha scattering experiment
what did rutherford expect when firing alpha particles at a gold foil
that the particles would pass straight through the sheet or only be slightly deflected however, most of the particles went straight through, and some deflected more than expected and few were deflected back the way the came
what is alpha radiation
when an alpha particle is emitted from the nucleus
what is an alpha particle (numbers)
2 protons and 2 neutrons like a helium nucleus
what can alpha particles be absorbed by
a sheet of paper
why are alpha particles not good for humans
they are strongly ionising
what is a beta particle
a fast moving electron released by the nucleus
what charge do beta particles have
-1
what can beta particles be absorbed by
a sheet of aluminium
for every beta particle emitted, what happens to a neutron
a neutron in the nucleus has turned into a proton
what are gamma rays
waves of electromagnetic radiation released by the nucleus
what can gamma rays be absorbed by
thick sheets of lead or metres of concrete
