Aim # 48: What are the advantages and disadvantages of radioactive isotopes? H.W. # 48 Study pp. 621-626 Ans. ques. p.630 # 27-32,34,53,54,56

Write an isotopic notation for the missing product Now Do: The nuclear equation below represents one of the many possible reactions for one fissionable nucleus. In this equation, X represents a missing product. 1n + 235U → 89Kr + X + 31n + 3.36 x 10-18J 0 92 36 Write an isotopic notation for the missing product represented by X in the nuclear equation.

I Advantages A. Energy Source 1. nuclear fission heavy → 2 smaller nuclei + energy nucleus e.g. nuclear reactors/power plants

2. nuclear fusion 2 small nuclei → heavier nucleus + energy e.g. 1H + 1H → 2H + 0e + energy 1 1 1 1 1H + 2H → 3He + energy 1 1 2 3He + 3He → 4He + 21H + energy 2 2 2 1 3He + 1H → 4He +0e + energy 2 1 2 1 Unlike fission, fusion produces no radioactive waste products. However, the temperature required for a fusion reaction is 40 million Kelvin.

14C forms naturally in the upper atmosphere. B. Medical Uses 1. Isotopes are used for diagnosing and treating cancer (131I and 60Co). 2. Radioisotopes are used as tracers in biomedical research (14C and 32P). C. Radioactive dating 14C forms naturally in the upper atmosphere. Phosphorylated molecules and DNA

14C photosynthesis plants eaten as food animals eaten as eaten as food food humans 14C → 14N + 0e 6 7 -1

The % of 14C in living organisms remains constant due to continuous consumption. However, when an organism dies, the level of 14C begins to decrease according to its half-life (5730y). e.g. If a fossil contains 25% of the 14C found in a living organism, how old is the fossil? Ans. 100% → 50% → 25% 2 half-lives, 2 x 5730y = 11460y

D. Food Irradiation- increases shelf-life II Disadvantages A. Nuclear radiation (energy) is dangerous to living organisms- it causes genetic damage and cancer. B. Nuclear waste- radioisotopes cannot be destroyed, and storage is a problem. C. Contamination of land and water