Radioactivity Flashcards
what is radioactivity?
where some isotopes have an unstable nucleus, and to become stable the nucleus gives out radiation, this could also be called radioactive decay
what type of process is radioactivity?
completely random
what is the activity in radioactivity?
the rate at which a source of unstable nuclei decay. it is measured in becquerel (Bq)
what does a geiger-muller tube do?
detects ionising radiation particles (alpha, beta, gamma), effectively counting the number of radiation events that occur
what are the 3/4 main types of radiation?
alpha, beta, gamma, (neutron)
what is alpha radiation?
alpha particles have 2 protons and 2 neutrons (same as the nucleus of a helium atom)
what is beta radiation?
beta particles have 1 electron which is ejected from the nucleus at high speed
what is gamma radiation?
gamma rays are a type of electromagnetic radiation from the nucleus
what are the properties of alpha particles?
(range in air, penetrating power, ionising power)
-particles are large and can travel around 5cm before colliding with air particles
-stopped by a single sheet of paper
-is very strongly ionising
what are the properties of beta particles?
-particles travel further, around 15cm in air before stopping
-stopped by a few millimetres of aluminium
-they are quite strongly ionising
what are the properties of gamma rays?
-can travel several metres in air before stopping
-stopped by several centimetres of lead
-they are very weakly ionising
what is the definition of half-life?
the time it takes for the number of nuclei of the isotope in a sample to halve
what are long and short half-lives?
long - if the nuclei take longer to decay
short - if the nuclei decay quickly
what is another way of defining half-life?
the time taken for the count rate from a sample containing an isotope to half its initial level
