atoms and nucelur radiaiton Flashcards
why do unstable nuceli give out radiation
. unstable nuclei undergo decay to become more stable
. As they release radiaiton their stability increases
what is the name of the process in which an unstable nucleus gives out radiaiton to become more stable
radioactive decay
define the activity of an unstable nucleus
activity is the rate of decay of a source of unstable nuclei
what is the unit of radioactive activity
becqueral- Bq
what is count-rate
the number of radioactive decays per second for a radioactive source
give an example of a detector that may be used to measure count-rate
Geiger-Muller tube
state 4 types of nucelur radiation
.alpha particles
.beta particles
.gamma rays
.nuetrons
what are the consittuents of an alpha particles
. two protons and two nuetrons
.it is the same as a helium nucleus
what is the range of an alpha particle through air
A few centimeters
what will stop beta radiaiton from passing through a point
. a thin sheet of aluminium
.serveral meters of air
what will stop gamma radiaiton from passing through a point
.several centimeters of lead
. a few meters of concrete
what type of radiaiton is most ionising
Alpha radiaiton
what type of radiaiton is least ionising
gamma radiation
state any changes to mass or charge that occur due to the emmision of a gamma ray
both mass and charge remain unchanged
describe the nature of radioactive decay
.random
.which nuclei decays and when is determined only by chance
.it is impossible to predict which nuclei will decay and when
define the half-life of an radioactive isotope
. the time it takes for the number of unstable nuclei in a substance to halve
. the time it takes for the count rate from a sample to fall to half its initial level
what is radioactive contamination
the presecence of unwanted radioactive nuclei on other materials
what is irradiation
. the process of exposing a material to nucleur radiaiton
.the material does not become radioactive
why is it important for the results of studies on the affects of radiaiton to be published and shared with other scientisits
. to allow the findings to be independantly checked
.this is known as peer review
