Radioactivity

Radioactivity

1. Types + measurement

   • So that nucleus can become more stable, the atom releases radiation. This is called radioactive decay.
     • Gamma Ray
       • γ
       • electromagnetic radiation from the nucleus
       • no change in element mass number or atomic number
     • Beta particle
       • β
       • Neutron turns to proton and an electron is ejected at high speed out of the atom
         • so the atomic number increases by 1 but the mass number doesn't change
     • Alpha particle
       • α
       • Have 2 neutrons and 2 protons. Like the element helium.
         • so when it leaves an atom, the mass number minuses 4 and the atomic number minuses 2
       • He
     • A neutron
   • Activity is the rate of decay
   • Measured in becquerel (Bq)
   • RANDOM
   • Half-life
     • Measured by decays per second = Counter-rate. eg Geiger-muller tube
     • Scientists use the half-life of an isotope to see how quickly it usually decays
       • half-life can vary but is determined by count-rate to fall to half the starting level

2. Contamination

   • unwanted decay of atoms
     • more decay more hazard
     • Irradiation
       • exposing an object to nuclear radiation - object doesn't become radioactive
     • background radiations in surroundings
       • measured in sieverts (Sv)

3. Use

   • exploring internal organs
   • control and destruction of unwanted tissue
     • However can be dangerous
       • can cause cancerous cells if they aren't destroyed
       • If swallowed, Alpha decay is bad
       • If external, Beta and Gamma are bad

4. Nuclear Fusion

   • Joining of two light nuclei to make one heavier one.

5. Nuclear Fission

   • splitting of a large unstable nucleus
     • All produce kinetic energy
     • chain reaction could lead to explosion
   • Neutrons are released + Gamma rays

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