Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Introduction to Nuclear Chemistry Chapter 19 I. Study of Nuclear Reactions Nuclear Reactions vs. Chemical Reactions Define “ Chemical Reaction”? Define “Nuclear Reaction” Reaction involving spontaneous emission of radiation by an unstable nuclei to a more stable nuclei of a different element. 226 88 226 88 Ra alpha particle Ra alpha particle 222 86 Rn 222 86 Rn Involves changes within nucleus. Atoms of each element do not balance. Spontaneous change of a radioisotope. 226 88 Ra alpha particle 222 86 Rn II. Types of Nuclear Radiation **Responsible for properties of top three!! Example Nuclear Reactions: Ra He 222 86 U e 239 93 226 88 4 2 239 92 Th * 230 90 0 -1 0 0 Rn Np 230 90 Th Rules For Balancing Nuclear Reactions: 1. The sum of the mass numbers of the reactants must equal the sum of the mass number of the products. *Total # nucleons remain the same. 2. The sum of the atomic numbers of the reactants must equal the sum of the mass number of the products. * Electrical charge remains the same. What kind of radiation is produced in the following nuclear reaction? 222 86 Rn Po ? 218 84 222 86 Rn Po ? 218 84 III. Radioactive Decay Rates Follows First Order Kinetics Commonly described by “half-life”. t1/2 “The time required for half the radioactive atoms in a sample to undergo decay.” ln [ A]t [ A]o kt Derived From Integrated Rate Law: [ A]t ln - kt [ A]o t 1/ 2 0.693 k Examples of Half-Lives Iodine-131 (t1/2 = 8 days) Example Problem: The value of t1/2 for I-131 is 8 days. How many I-131 atoms will remain after 24 days in a sample originally containing 6.4 x 1016 I-131 atoms?