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Radioactive Elements

Radioactive Elements. Radioactivity: An Imbalance of Forces in the Nucleus. Radioactivity: An Imbalance of Forces in the Nucleus. Strength of Force depends on distance !. Radioactivity: An Imbalance of Forces in the Nucleus. Strength of force depends on distance

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Radioactive Elements

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  1. RadioactiveElements

  2. Radioactivity: An Imbalance of Forces in the Nucleus

  3. Radioactivity: An Imbalance of Forces in the Nucleus Strength of Force depends on distance !

  4. Radioactivity: An Imbalance of Forces in the Nucleus • Strength of force depends on distance • SO.. Larger nuclei are less stable • Strong force less effective in holding nucleus together • Electrical (repulsive) forces have greater impact • Elements DECAY(come apart) over time

  5. Radioactivity: Definition • Radioactivity: the process by which certain elements emit particular forms of radiation. • Radioactive: any element that emits any of these forms of radiation.

  6. Half Life: Measures Decay Rate • Half life refers to amount of time it takes for ½ of the radio active sample to decay • Half life for a particular isotope is always the same

  7. Half Life • Half life measures decay rate • Ex. Every1620 years ½ of a sample of radium-226 will have decayed. 1620 years 3240 years 6480 years Start

  8. Application: Carbon Dating

  9. Reaction in a Nuclear Reactor

  10. RadioactiveElements Part 2 Jan 9, 2014

  11. Different Ways to Decay –Types of Radioactive Particles Alpha Particles (α)– 2 protons and 2 neutrons Beta Particles (β)– split 1 neutron into 1 proton and 1 electron Gamma Particles (ɣ) – emits a photon

  12. Half-life: Exponential Decay

  13. Decay of 238U: Natural Decay Chain

  14. Decay of 238U: Natural Decay Chain • decays, through alpha-emission, with a half-life of 4.5 billion years to thorium-234 • which decays, through beta-emission, with a half-life of 24 days to protactinium-234 • which decays, through beta-emission, with a half-life of 1.2 minutes to uranium-234 • which decays, through alpha-emission, with a half-life of 240 thousand years to thorium-230 • which decays, through alpha-emission, with a half-life of 77 thousand years to radium-226 • which decays, through alpha-emission, with a half-life of 1.6 thousand years to radon-222 • which decays, through alpha-emission, with a half-life of 3.8 days to polonium-218 • which decays, through alpha-emission, with a half-life of 3.1 minutes to lead-214 • which decays, through beta-emission, with a half-life of 27 minutes to bismuth-214 • which decays, through beta-emission, with a half-life of 20 minutes to polonium-214 • which decays, through alpha-emission, with a half-life of 160 microseconds to lead-210 • which decays, through beta-emission, with a half-life of 22 years to bismuth-210 • which decays, through beta-emission, with a half-life of 5 days to polonium-210 • which decays, through alpha-emission, with a half-life of 140 days to lead-206, which is a stable nuclide.

  15. Types of Radioactive Particles Alpha Particles– 2 protons and 2 neutrons Beta Particles– split 1 neutron into 1 proton and 1 electron Gamma Particles– emits a photon

  16. Types of Radioactive Particles Alpha Particles– 2 protons and 2 neutrons • Lowest Energy • Still fast enough to do damage • Easily stopped • Relatively large size and mass • Large enough to do damage • Easily stopped • +2 Charge. • Tends to pick up electrons & convert to Helium

  17. Types of Radioactive Particles Alpha ParticlesEmits: 2 p + 2 nExample:Uranium-238  Thorium-234 + Helium-4

  18. Types of Radioactive Particles Beta Particles - 1 n  1 p + 1 e- (emits e-) • Higher Energy • Harder to stop than α particle • Becomes part of material when stopped • -1 Charge. • Proton joins nucleus • Electron (-1 charge) is emitted

  19. Types of Radioactive Particles Beta ParticlesLoses: 1 nGains: 1 pEmits: 1 e- Example: Thorium -234  Protactinium – 234 + electron

  20. Types of Radioactive Particles Gamma Particles– emits a photon • Highest Energy • Can do significant damage • Hard to stop • No charge • Doesn’t combine with other materials • No mass • Hard to stop

  21. Types of Radiation: Energy (Resistance to being stopped)

  22. Types of Radiation: Charges -1 +2 Neutral

  23. Types of Radiation: Charges +2 Neutral -1

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