radiation

• what is radioactive decay?

  when unstable isotopes decay into other elements and give out radiation as they try to become more stable
• what is ionising radiation?

  radiation that knocks electons off atoms, creating positive ions
• what is an alpha particle?

  helium nucleus

  -they dont penetrate very far and can be absorbed by a sheet of paper

  -they are strongly ionising
• what is a beta particle?

  a fast moving electron

  -can be absorbed by a 5mm thick sheet of aluminium

  -moderately ionising
• what are gamma rays?

  high energy waves of electomagnetic radiation

  -they penetrate far and can be absorbed by lead or concrete

  -they are weakly ionising
• what is alpha decay?

  when an atom emits an alpha particle, the mass number reduces by 4 and the atomic number reduces by 2
• what is beta decay?

  when a beta decay occurs, the protons in the nucleus increase by 1
• what is irradiation?

  exposure to radiation.

  risks:

  -beta and gamma can penetrate the body and get to delicate organs
• what is contamination?

  radioactive particles getting onto objects.

  risks:

  -can damage healthy cells
• what is half life?

  the time taken for radioactive nuclei in an isotope to halve