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Agenda 3/3/10. Pick up your lab Take out homework - Isotopes WS Did you take the moodle quizzes ? Notes on balancing decay reactions Practice balancing decay reations WS 6 th period – review last week’s quiz
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Agenda 3/3/10 • Pick up your lab • Take out homework - Isotopes WS • Did you take the moodlequizzes? • Notes on balancing decay reactions • Practice balancing decay reations WS • 6th period – review last week’s quiz Learning Goal: Students will be able to write balanced decay reactions for alpha and beta decay.
Isotope Review 3 Neon-22 H 1 2. Determine the name and symbol for an isotope whose atoms contain 3 protons and 4 neutrons. 1. Determine the number of protons and neutrons in each of the following isotopes.
Isotope Review 3 10 Protons 12 Neutrons Neon-22 H 1 Proton 2 Neutrons 1 2. Determine the name and symbol for an isotope whose atoms contain 3 protons and 4 neutrons. 1. Determine the number of protons and neutrons in each of the following isotopes. 7 3 Lithium-7 Li
Decay Reactions When a radioactive isotope decays… - matter is conserved. - total # of particles in the nucleus is conserved. - total (neutral) charge of atom is conserved.
Decay Reactions 238 92 U → ___ + ___ We can use those conservation ideas to predict decay products. For example, when Uranium-238 decays by alpha decay… alpha particle daughter nucleus
Decay Reactions 238 92 4 2 U → He + ___ We can use those conservation ideas to predict decay products. For example, when Uranium-238 decays by alpha decay… alpha particle daughter nucleus
Decay Reactions 234 90 238 92 4 2 Th U → He + We can use those conservation ideas to predict decay products. For example, when Uranium-238 decays by alpha decay… alpha particle daughter nucleus
Another Example 211 83 Bi → ___ + ___ Write the decay reaction formula for the alpha decay of Bismuth-211. alpha particle daughter nucleus
Another Example 207 81 211 83 4 2 Tl Bi → He + Write the decay reaction formula for the alpha decay of Bismuth-211. alpha particle daughter nucleus
One More Alpha-Decay Example 31 14 ___ → ___ + Si A certain radioactive isotope decays by alpha decay, producing Silicon-31 as the daughter nucleus. What was the original isotope? alpha particle original nucleus
One More Alpha-Decay Example 35 16 4 2 31 14 S → He + Si A certain radioactive isotope decays by alpha decay, producing Silicon-31 as the daughter nucleus. What was the original isotope?
Beta Decay Beta decay still obeys the same general conservation rules as alpha decay, but it works a little differently because of what beta particles are. A beta particle is basically just… an electron emitted from the nucleus!
Beta Decay This top number counts how many total protons and neutrons are present in this particle. 0 e -1 So what would the symbol for a beta particle look like, in a decay reaction formula? Remember, this bottom number is the # of protons, which could also be thought of as the charge of the particle.
Beta Decay Example 14 6 C → ___ + ___ Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? betaparticle daughter nucleus
Beta Decay Example 0 -1 14 6 e C → + ___ Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? betaparticle daughter nucleus
Beta Decay Example 0 -1 14 7 14 6 e N C → + Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? betaparticle daughter nucleus
Beta Decay Example 0 -1 14 7 14 6 e N C → + What’s occurring in the nucleus during beta decay, for the total #of particles in the nucleus to remain constant, but for proton # to increase? One of the neutrons is ‘breaking’ into a proton and an electron.
One More Beta-Decay Example 32 15 P → ___ + ___ Write the decay reaction formula for the beta decay of Phosphorous-32. betaparticle daughter nucleus
One More Beta-Decay Example 0 -1 32 16 32 15 e S P → + Write the decay reaction formula for the beta decay of Phosphorous-32. betaparticle daughter nucleus
Decay Reaction Practice 45 20 • (beta) • (alpha) 210 84 • (alpha) • (beta) Ca Po Determine the daughter nucleus produced when each of the following radioactive isotopes decay in the manner stated. 234 94 24 11 Pu Na
45 21 206 82 Sc Pb Decay Reaction Answers 230 92 24 12 U Mg