Azra radioactive decay

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Azra radioactive decay

  1. 1. RADIOACTIVE DECAY by : azyulail azra
  2. 2. radioactivity particles emission of energetic The spontaneous disintegration of an unstable nucleus photons • cannot be detected. • energetic enough to knock electrons out of the atoms of a medium to produce ions. • also known as ionising radiation.
  3. 3. radioactive emissions α-particles helium nucleus γ-rays electromagnetic waves
  4. 4. differences α-particles β-particles Charge Positive charge Speed Up to 10% Up to 99% Speed of of speed of of speed of light light light Nuclide notation 4 He 2 Negative charge γ-rays 0 -1 e No charge (neutral) -
  5. 5. Penetrating power γ-rays α-particles β-particles # Average # High # Low # Stopped by # Stopped by a few a sheet of millimeters of paper aluminium # A few centimeters of lead can absorb a significant amount of it
  6. 6. α-particles β-particles Effect of magnetic field Small deflection γ-rays Large No deflection deflection in the opposite direction of the αparticles
  7. 7. α-particles β-particles Effects of electric field Small Large deflection towards negatively charged plate deflection towards positively charged plate γ-rays No deflection
  8. 8. α-particles β-particles Range in air Several centimetres Several metres γ-rays Several hundred metres Tracks in Straight and thick cloud chamber lines Thin and Very fine wavy lines short lines Ionising power Medium Strong Very weak
  9. 9. radioactive detectors Cloud chamber Photographic Film Geiger-Muller Tube Spark counter
  10. 10. cloud chamber - to show the path of ionizing radiation. - formed in the same way as the condensation trails behind a high-flying aeroplane
  11. 11. α - particles β - particles γ - rays
  12. 12. photographic film - Found in badges worn by the staff at radiation laboratories
  13. 13. GM tube Radiation Enters through mica window 240 V Ionizes argon gas Pulse of current produced Pulse of current counted using ratemeter/scaler Number of counts period of time
  14. 14. spark counter Suitable for alpha rays ionizes the air between the gauze and the wire radioactive source is brought near sparks are produced
  15. 15. radioactive decay • Nuclei that have too few or too many neutrons are unstable. the process of a nucleus changing to a more stable nucleus while emitting most likely to be • radiation. • Nucleus before the decay = parent product of the decay • • nuclide = daughter nuclide. The daughter nuclide may still be unstable and will eventually decay into another nuclide. This process continues until a stable nuclide is reached.
  16. 16. Alpha decay -This type of decay usually happens to the heavier unstable nuclei. -The proton number is reduced by 2 while the nucleon number is reduced by 4 and emit αparticles 238 92 U 238 – 4 = 234 92 – 2 = 90 Th + 4 2 He
  17. 17. 14 6C 14 - 0 = 14 N 6 - (-1) = 7 + 0 -1 e Beta decay -Beta decay usually occurs for nuclei that have an excess of neutrons. - There is no change in the nucleon number but the proton number increases by 1 and emit β-particles
  18. 18. Gamma decay -occurs when an unstable nucleus releases its excess energy [ high frequency electromagnetic waves ] called γ-rays. -no change in proton number and nucleon number but emit γ-rays -A nucleus that undergoes alpha or beta decay may 60 Co 27 also emit γ-rays. 60 27 Co + γ
  19. 19. half-life • Time taken for undecayed nuclei to be reduced to half of its original number • The number of unstable nuclei have not decayed decreases with time. • The half-life constant ~ the decay process is random and large.
  20. 20. 128 64 Original number of undecayed nuclei = 256 Half of original number = 128 It takes 3 hours for the undecayed nuclei to be reduced to half of original number. ∴ 1 half-life = 3 hours
  21. 21. Radionuclide Half-life (T1/2) 90Sr Strontium-90 28.5 years 137Cs Caesium-137 30.1 years 226Ra Radium-226 1600 years 14C Carbon-14 5736 years 40K Potassium-40 1.28 x 108 years
  22. 22. Thank you !!!

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