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Unit 6 Radioactivity and Nuclear Decay

Unit 6 Radioactivity and Nuclear Decay. Nuclear Changes. Chapter 10.1. What is Radioactivity?. Radioactivity. Radioactivity. Radioactive decay is the disintegration of an unstable atomic nucleus into one or more different nuclides .

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Unit 6 Radioactivity and Nuclear Decay

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  1. Unit 6Radioactivity and Nuclear Decay

  2. Nuclear Changes Chapter 10.1

  3. What is Radioactivity?

  4. Radioactivity

  5. Radioactivity • Radioactive decay is the disintegration of an unstable atomic nucleus into one or more different nuclides. • After radioactive decay, the element changes into a different isotope of the same element or into an entirely different element.

  6. Radioactivity • Nuclear radiation is the release of particles from the nucleus during radioactive decay. • These particles can either be alpha, beta, or gammaparticles.

  7. Types of Radiation • Alpha particles can be stopped by paper. • Beta particles can be stopped by aluminum. • Gamma particles can be stopped by lead.

  8. Alpha Decay • Alpha particle (α) is a positively charged particle that consists of two protons and two neutrons and that is emitted from a nucleus during radioactive decay. • This is a helium nucleus.

  9. Alpha Decay (Atomic Mass #) (Atomic #) 3. Since the atomic # = 82, then

  10. Beta Decay • Beta particle (β) is an electron or positronthat is emitted from a nucleus during radioactive decay. • A positron is a positivelycharged electron, NOTa proton.

  11. Beta Decay (Atomic Mass #) (Atomic #) 3. Since the atomic # = 84, then

  12. Gamma Decay • Gamma ray (γ) is a high-energy photon emitted by a nucleus during fission and radioactive decay. • Aphotonis a packet of electromagnetic radiation or energy.

  13. Gamma Decay (Atomic Mass #) (Atomic #) 3. Since the atomic # = 84, then

  14. Neutron Emission • Neutron emission consists of matter that is emitted from an unstable nucleus • Neutronshave no charge, and therefore do not want to interact with other particles.

  15. How old are rocks? • If you were asked to determine the age of a rock, you would probably not be able to do so easily. • How, then, would you go about finding the rock’s age?

  16. Radioactive Decay Rates • One way to find the age involves radioactive decay. • It is possible to predict the time required for half of the nuclei in a given radioactive sample to decay. • Half-life is the time required for half of the sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope.

  17. Half-Life and Exponential Decay • The definition of half-lifetells us that after the first half-life time of a radioactive sample has passed, halfof the sample remains unchanged. • After the next half-life, half of the remaining half decays, so only a quarterof the original element remains. • Of that quarter, half will decay in the next half-life, so only one-eighth will remain unchanged • This relationship is called exponential decay.

  18. Half-life Time Frames

  19. Half-Life Equations Half- Life Fractions 1st = 1/2 # of 2nd = 1/4 HL’s3rd = 1/8 4th = 1/16 5th = 1/32 1st = 1/2 2nd= 1/4 3rd = 1/8 4th = 1/16 5th = 1/32

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