radioactivity Flashcards
number of protons is…
atomic/proton number
number if protons+neutrons is…
mass number
mass of nucleus is…
relative atomic mass
unit for radioactive activity
becquerel (Bq)
what is alpha made up of
2 protons and 2 neutrons
what stops alpha decay
a FEW cm of air or piece of paper
how ionising is alpha
highly ionising
what is beta made up of
an electron - emitted after a neutron turns into a proton
what stops beta decay
a few mm of aluminium
how ionising are beta particles
weakly ionising
what is a gamma ray
high energy EM wave
what stops gamma decay
a few cm of lead
how ionsing are gamma rays
very weakly ionising
what effect does alpha have
lowers mass by 4
lowers atomic number by 2
what effect does beta have
increases atomic number by one
what effect does gamma have
no effect
what is a half-life
the time taken for one half of the nucleus to decay
what is fission
- neutron hits a stable 235U nucleus to make it unstable 236U
- unstable 236U nucleus splits to make 2 lighter ‘fission fragments’
- releases neutrons that cause a chain reaction
what do control rods do
maintain constant rate of reaction by absorbing excess neutrons
made from boron or cobalt
what do moderators do
slow down neutrons to continue reaction
made from graphite
what does shielding do
prevents workers from being exposed to radiation
made from steel or concrete
what is fusion
2 light nuclei fuse together to create a heavier nucleus - less mass than the previous lighter combined
radioactive uses:
- smoke alarm
- medical diagnosis and treatment
- finding leaks
- nuclear batteries
- sterilization
- manufacturing
- finding the age of something
