Nuclear decay

Radiation

emission of energy from nucleus of an atom particle wave

Radioactive

ability of substance to emit radiation

Radioactive decay

nucleus of atom becomes unstable and changes into isotope with emission of radiation to become stable

Radionuclide

radioactive isotope

Nucleus can be unstable due to

too many p+ n0

an ——— nuclei upsets strong —— forces holding —- together

atom starts to decay to try and balance, releases p+ and n0 particles, waves

Alpha decay

nucleus ejects 2p+ + 2n0, identical to helium atom

change after alpha decay

atomic number -1 mass number -4

where does alpha decay occur

atoms with heavy nuclei (mass no >100)

Beta decay

nucleus ejects beta particle, identical to electron

change that occurs after beta decay

converts n0 to p+ atomic number +1

gamma decay

p+ and n0 rearranged inside nucleus, emit gamma ray (wave)

change that occurs after gamma decay

no change to atomic no or mass no

alpha radiation stopped by

dead skin cells, layers of paper

beta radiation stopped by

1mm alumimum

gamma radiation stopped by

concrete / lead

alpha radiation on living organisms

if ingested: lung damage, DNA and cell damage

beta radiation on living organisms

radiation burns to skin/eyes, damages internal organs

gamma radiation on living organisms

damages tissues organs, increases cancer risk, changes DNA

Half-life

time taken for ½ radioactive nucleus to decay and stabilise