Physics P7

Physics P7

1. atoms and radiation

   • alpha decay
     • Alpha radiation is the release of an alpha particle, which is 2 protons and 2 neutrons. Occurs in very heavy elements e,g. uranium and radium. They have too many protons. By releasing an alpha particles, becomes more stable
   • beta decay
     • In beta decay, a neutron in the nucleus spontaneously decays into a proton and an electron. The proton stays in the nucleus, while the electron flies out
   • gamma decay
     • If a nucleus still has energy after releasing alpha particles or beta particles it can get rid of the extra energy by releasing a gamma ray. Gamma rays are waves. May be emitted alongside alpha and beta particles

2. the discovery of nucleus

3. changes in the nucleus

   • protons neutrons and electrons make up an atom
   • An isotope is when the proton are the same number and the neutrons are different number. Atomic number is the same but the mass number is different

4. activity and half life

   • activity
     • a radioactive source is the number of unstable atoms in the source that decay per second
   • count rate
     • number of counts per second
   • half life
     • the average time taken for the count rate to fall by half is always the same

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