CHEM 1120 1nd Edition Lecture 9 Outline of Last Lecture I. Catalysisa. Catalystb. Homogeneous vs Heterogeneous catalysisc. EnzymesII. Intro to Chapter 21: Nuclear Chemistrya. Chemical vs. Nuclear ReactionsIII. Radioactivitya. Types of Emissionsb. Balancing Nuclear EquationsOutline of Current Lecture I. BalancingII. Patterns of Nuclear stabilitya. Radioactive decay seriesb. Additional trendsIII. Nuclear Transmutationsa. Particle AcceleratorsIV. Rates of Radioactive Decaya. Decay rate (A) = -Change in N/Change in t = kNb. Carbon-14 datingCurrent LectureI. Balancinga. Must balance top numbers and bottom numbers on each sideb. Use the building blocks that are common to usThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Patterns of Nuclear Stabilitya. Only 265 isotopes are stable-lie in Belt of Stabilityb. Nuclei with >83 protons are radioactivec. Magic numbers- nuclei with 126 neutrons are usually more stabled. Nuclear stabilityi. Radioactive decay predictableii. Above the belt of stability (too many neutrons; N/Z >>1)1. Loss of electroniii. Below the belt of stability (too many protons, N/Z <<1)1. Loss of a positron, or gain of electroniv. Nuclei with >83 protons (always unstable)1. Alpha emission-loss of He isotopee. Radioactive Decay seriesi. 80 radioactive isotopes occur naturally, why aren’t they all totally decayed?1. Radioactive series produce isotopes, each series is fathered by a very long half-life isotopef. Additional trendsi. Magic numbers-certain numbers of protons and neutrons tend to be more stable than othersii. Nuclei with an even number of protons and neutrons tend to be more stable III. Nuclear Transmutationsa. Nuclear transmutation: induced conversion of one nucleus into anotherb. Over 100 radioisotopes have been producedi. First artificial radioisotope produced by Curies ii. Al foil bombarded with alpha particlesiii. Reactant nucleus (Particle in, particle out) product nucleus (shorthand notation)c. Particle Acceleratorsi. Impart high kinetic energies to particles by placing them in an electric field usually in combination with a magnetic field1. Linear accelerator: used alternating voltages to change the charges in a series of tubes2. Cyclotron: uses electromagnets to give particle spiral path3. Synchrotron: synchronously increasing magnetic field to make the path circularii. Can be miles huge! (2 miles long, 10 square miles, 17 miles long, etc)iii. Applications: produce radioisotopes, studying nature of matter, IV. Rates of Radioactive decaya. Radioactive nuclei decay at a characteristic rate independent of the chemical substance  first-order kinetic processb. Decay rate (A) = -Change in N/Change in t = kNi. K=decay constantii. N=number of radioactive nucleiiii. Activity: Aiv. Specific activity: decay rate/gv. Becquerel: one nuclear disintegration per secondvi. Curie: 3.7 x 10^10 disintegrations per second (d/s)c. T1/2=.693/kd. Ln (Nt/No) = -kte. Disinteg. = measured in nuclides f. Carbon-14 datingi. Atmospheric CO2 contians a fixed C-14/C-12 ratioii. Photosynthesis results in biochemical with this same ratioiii. Upon death, the decaying C-14 is not replenished iv. Dead objects have a C-14/C-12 ratio less than that of the atmosphere v. Carbon-14 has a half-life of 5730 yearsvi. Can be used to date objects up to 36000 years oldvii. For older materials, U-238/Pb-208 dating is