4.2: atoms and nuclear radiation

when do nuclei give out radiation

when they’re unstable

unstable nuclei give out radiation

because they undergo decay to become more stable and as they release radiation they become more stable

an unstable nucleus giving out radiation to become more stable is called

radioactive decay

the activity of an unstable nucleus is

the rate of decay of the a source of unstable nuclei

what is radioactive decay measured in

becquerel (Bq)

count-rate is

the number of radioactive decays per second from a radioactive source

what can detect count rate

geiger-muller tube

the four types of nuclear radiation are

alpha,beta particles, gamma rays and neutrons

alpha particles are made up of

two protons and two neutrons, same as a helium nucleus

the range of alpha particles through air is

a few centimetres (2-10)

what stops beta radiation from passing through a point

thin sheet of aluminium, several metres of air

what stops gamma radiation from passing through a point

several centimetres of lead, few meters of concrete

……………….. is the most ionising radiation

alpha

………………. is the least ionising radiation

gamma

during gamma radiation, mass and charge

remain unchanged

the nature of radioactive decay is

random, when a nuclei decays and which one decays is determined by chance, it is impossible to predict which nuclei will decay and when

the half life of a radioactive isotope is

the time it takes for the amount of unstable nuclei in a substance to half or the time it takes for the count rate to be half its initial level

radioactive contamination is

the presence of unwanted radioactive nuclei on other materials

irradiation is

the process of exposing a material to nuclear radiation, it does not become radioactive

it is important to share effects of radiation to be shared with other scientists because

it allows findings to be independently checked, called peer review