P5: Radioactive Materials

P5: Radioactive Materials

1. Types of Ionising Radiation

   • Alpha
     • 2 neutrons, 2 protons. Big, heavy, slow moving.
   • Beta
     • Identical to an electron, move quite fast and are small. For every beta particle emitted, a neutron turns into a proton in nucleus.
   • Gamma Rays
     • Helps get rid of extra energy, high frequency, no mass or charge, just transfers energy.
   • If nucleus contains lots of neutrons, it may just throw it out. The nuclear mass changes because of that, so it becomes a different isotope of the same element.

2. Balancing Nuclear Equations

   • Emitting an Alpha Particle
     • Mass decreases by 4 - loses 2 protons and neutrons, charge decreases by 2.
   • Emitting a Beta Particle
     • Mass doesn't change - lost neutron but gained proton, nuclear charge increases by 1
   • Emitting a Gamma Ray
     • Mass or charge doesn't change

3. Half-Life

   • The average time taken taken for its activity to halve.

4. Dangers of Radioactivity

   • Ionising Radiation Harms Living Cells
     • Ionising Radiation enter living cells and interact with molecules. Lower doses damage living cells by causing mutations in the DNA, which causes the cell to divide uncontrollably (cancer). Higher doses kill cells completely, which causes radiation sickness if a lot of cells get blasted at once.
   • Hazards Depends on the Type of Radiation
     • Beta and gamma are the most dangerous (outside the body), because beta particles and gamma rays can penetrate the body and get to delicate organs. Alpha particles are the least dangerous because they can't penetrate the skin, easily blocked by a small air gap. Inside the body, alpha particles are most dangerous, because they do all their damage in a localised area. Beta and gamma rays are the least dangerous in the body.

5. Uses of Radiation

   • Tracers in medicine - Gamma
   • Radiotherapy - Treatment of cancer

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