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 Learning Goal: Students will be able to write balanced decay reactions for alpha and beta decay.

Isotope Review 1. Determine the number of protons and neutrons in each of the following isotopes. H 3 1 Neon Determine the name and symbol for an isotope whose atoms contain 3 protons and 4 neutrons.

Isotope Review 1. Determine the number of protons and neutrons in each of the following isotopes. H 3 1 Neon Determine the name and symbol for an isotope whose atoms contain 3 protons and 4 neutrons. 1 Proton 2 Neutrons 10 Protons 12 Neutrons Lithium-7Li 7373

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 We can use those conservation ideas to predict decay products. For example, when Uranium- 238 decays by alpha decay… U →+___ alpha particle daughter nucleus

Decay Reactions We can use those conservation ideas to predict decay products. For example, when Uranium- 238 decays by alpha decay… U →He ___ alpha particle daughter nucleus

Decay Reactions We can use those conservation ideas to predict decay products. For example, when Uranium- 238 decays by alpha decay… U →He alpha particle daughter nucleus Th

Another Example Write the decay reaction formula for the alpha decay of Bismuth-211. Bi →+___ alpha particle daughter nucleus

Another Example Write the decay reaction formula for the alpha decay of Bismuth-211. → alpha particle daughter nucleus He Tl Bi

One More Alpha-Decay Example A certain radioactive isotope decays by alpha decay, producing Silicon-31 as the daughter nucleus. What was the original isotope? Si →+___ alpha particle ___ original nucleus

One More Alpha-Decay Example A certain radioactive isotope decays by alpha decay, producing Silicon-31 as the daughter nucleus. What was the original isotope? Si →+He 4242 S 35 16

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 So what would the symbol for a beta particle look like, in a decay reaction formula? e Remember, this bottom number is the # of protons, which could also be thought of as the charge of the particle. 0 This top number counts how many total protons and neutrons are present in this particle.

Beta Decay Example Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? C 14 6 →+___ beta particle daughter nucleus

Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? C 14 6 →+___ beta particle daughter nucleus e 0 Beta Decay Example

Now that you know the symbol, predicting decay products should be easy enough. What are the products when Carbon-14 decays by beta decay? C 14 6 →+ beta particle daughter nucleus e 0 N 14 7 Beta Decay Example

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? C 14 6 →+ One of the neutrons is ‘breaking’ into a proton and an electron. e 0 N 14 7 Beta Decay Example

One More Beta-Decay Example Write the decay reaction formula for the beta decay of Phosphorous-32. P →+___ beta particle daughter nucleus

Write the decay reaction formula for the beta decay of Phosphorous-32. P → beta particle daughter nucleus + S e 0 One More Beta-Decay Example

Decay Reaction Practice Determine the daughter nucleus produced when each of the following radioactive isotopes decay in the manner stated. 1. (beta) 2. (alpha) Ca Pu (alpha) 4. (beta) Po Na 24 11

Decay Reaction Answers Sc U Pb Mg 24 12