radioactivity Flashcards
ionising radiation
cloud chamber
used to detect the presense of types of radiation. when the air is ionisded the liquid condenses and leave tarcks of droplets marking the path of radiation.
alpha particle range
short ranged but strong ionisation a thin paper absorbs it
range of beta decay
less ionising so aluminim can stop it
range of gamma rays
less ionising enrgy for lead can absorb it
danger of radiation
causes ionisation so can damnge living cells
parent nucleus
nucleus before decay
daughter nucleus
nucleus after decay
alpha decay
parent–> daughter nucleus + helium
releases energy
why does beta minus occur?
too many neutrons
beta minus decay
parent–> daughter nucleus+ electron+ electron antineutrino
why does beta plus decay occur?
too many protons so a proton convert into a neutron
beta plus decay equation
parent–> daughter+ positron + lectron antineutron
why does gamma decay occur?
surplus energy following alpha or beta decay #
random
cannot predict when its goning to occur.
every nucleus has equal changecs of decaying
spontaneous
not affect by the presence of other nuclei and external factors like pressure
half life
the average time it tske for half the number of active nnuclei in a smaple to decay.
how is count rate measured?
gm tube
what is the activity of a source?
the rae at which nuclei decay/ number of alpha particles emitted per unit time
decay constant
the probability of decay of an individual nucleus per unit time
the ratio of carbon-12 to carbon-14 is what?
constant
once an organism dies what happens to the carbon-14?
starts to decay
how are carbon-14 formed?
high speed proton collide with atoms adn produce neutron. thede neutrons collide with nitrogen-12 to form carbon-14 and carbon-14 undegoes beta minus to make nitrogen again
assumption of carbon dating?
assumption that ration of carbon-12 to 14 ramins constant
limitation to carbon dating
emission of fossil duels may have reduced the ratio, solar flares and testing of nuclear bombs
