Chemistry Unit 5 Exam Study Guide Nuclear Chemistry

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1 Chemistry Unit 5 Exam Study Guide Nuclear Chemistry Define the following vocabulary terms: Radioactivity Radiation Alpha Particle Beta Particle Gamma Ray Transmutation Half-life Nuclear Decay Nuclear Fission Nuclear Fusion Protostar Main-sequence Star Red Giant White Dwarf Black Dwarf Supernovae Black Hole Neutron Star Proton Cycle CNO Cycle Chain reaction Conceptual Review 1. State what occurs as a radioactive isotope goes through decay. -the element will undergo alpha, beta, and/or gamma decay and change into a more stable nucleus.. State where the radioactive isotopes can be found on the periodic table. -atoms with greater than 8 (83 or more) protons are unstable isotopes, usually the bottom of the periodic table. i.e. the actinides & lanthanides 3. List the composition, mass, and charge of an alpha particle. Mass charge mass = protons + neutrons 4 He 4 = + neutrons neutrons = 4. List the composition, mass, and charge of a beta particle. Mass mass = 0 protons = 0 charge 0 e neutrons = 0 electrons = 1 1

2 5. List the composition, mass, and charge of a gamma ray. -gamma ray is pure energy (non matter) -contains no mass, no protons, no electrons, no neutrons 6. Rank the radiation particles in order from largest to smallest. Alpha, beta, gamma 7. Rank the radiation particles by their ability to penetrate lead from least to greatest. Alpha, beta, gamma 8. Differentiate between a chemical reaction and a nuclear reaction. A chemical reaction will rearrange reactant elements into different compounds on the product side of the equation. (Same elements) Al(OH) 3 + Mg Mg(OH) + Al A nuclear reaction will produce a different element (nuclear change) 6 C 0 1 e + 7 N Nuclear changes occur at temperatures (1,000,000 C) significantly higher then chemical changes (,000 C) 9. Describe what occurs to the amount of a radioactive isotope after a half-life of the radioactive isotope. -the amount is cut in half (i.e. 10 grams decays to 5 grams) 10. Differentiate between nuclear fission and fusion by completing the following chart. How the nuclei change Nuclear Fission SPLIT - FISSION IS DIVISION Nuclear Fusion JOIN / MERGE/FUSE Type of fuel used Amount of energy produced Where the reaction occurs Temperature change LARGE, UNSTABLE NUCLEI SUCH AS U-38, Pu-39 MASSSIVE AMOUNTS NUCLEAR POWER PLANTS, NUCLEAR WEAPONS SMALL NUCLEI, USUALLY H & He MASSIVE AMOUNTS (SIGNIFICANTLY MORE THEN FISSION) STARS & OUR SUN 1,000,000 C 100,000,000 C Masses of reactants to products Other important info REACTANTS ARE LARGER THEN PRODUCTS CHAIN REACTION REACTANTS ARE SMALLER THEN PRODUCTS

3 11. List the benefits of radiation. food safety, source of vitamin D, plants use for photosynthesis, source of Energy on Earth 1. List the major health effects of radiation exposure and the factors related to exposure. Sunburn, damages DNA Radiation exposure depends on amount of exposure (size) and frequency of exposure (daily or once in your whole life. 13. Sequence the stages of life for a low-mass star. Protostar, main sequence, red giant, white dwarf, black dwarf. Sequence the stages of life for a high-mass star. protostar, massive main sequence, red supergiant, supernova, black hole or neutron star 15. Explain how most stars produce energy and the specific processes by which energy is produced. Most stars undergo fusion, which produces massive amounts of energy 16. State what occurs in a star once the hydrogen fuel has been consumed. Helium fusion begins 17. Define the solar absorption spectrum. List the elements that are found in the sun s atmosphere. The sun emits radiation, the human eye can see only the visible spectrum as white light. A prism will separate the white light into the rainbow of colors known as continuous spectrum. The emission spectrum is the specific wavelengths elements emit when given extra energy. The absorption spectrum is the specific wavelenths that are absorbed by atmospheric gases surrounding the star. THE ELEMENTS FOUND IN SUN S ATMOSPHERE: H, He, Na, Ca, Fe Note longer wavelengths like red, have less energy. Shorter wavelengths like blue have more energy. Practice Questions 1. Identify each reaction as chemical, physical, or nuclear: a. U + 1 n 91 Kr + Ba n NUCLEAR CHANGE b. HCl + CaCO 3 CaCl + H O + CO CHEMICAL CHANGE c. H O (g) H O (l) PHYSICAL CHANGE d. U 31 Th + 4 α NUCLEAR CHANGE 9 90 e. C (graphite) C (diamond) PHYSICAL CHANGE f. HNO 3 + Zn ZnNO 3 + H CHEMICAL CHANGE g. C 0 β + N NUCLEAR CHANGE 6 1 7

4 . Which of the following elements are always radioactive? a. Na NO b. Fr YES c. Ga NO d. Rn YES e. V NO 3. Identify each reaction as nuclear decay, nuclear fission, or nuclear fusion: a H 4 He e FUSION b. c. d. e. U + 1 n Ba + Kr n FISSION C 0 β + N NUCLEAR DECAY H H 4 He n FUSION 39 Pu + 1 n Xe + Zr n FISSION Complete the following nuclear reactions: a. Ra e Ac 1 6 b. Ac + 1 n Mo 7 47 Ag c. 7 Al He P n d. e. U + 1 n 131 Sn n Mo 0 H + H p H 1

5 5. Write out and balance the following nuclear reactions: a. Polonium-10 undergoes an alpha decay Po 4 06 He + 8 Pb b. Lead- undergoes a beta decay. 8 Pb 0 e Bi c. Technetium-99 releases a gamma ray Tc γ Tc d. Uranium-38 undergoes an alpha decay then a beta decay U 4 34 He + 90 Th 0 34 e Pa 6. The half-life of berkelium-47 is 1,380 years. How much of a 65 g sample will remain after 5,000 years? 5,000 years = (.5) 3.6 = grams 1,380 years 7. You have a 100 gram sample of Cobalt-60. If, after years, you only have 1.50 grams remaining, what is the half-life of Cobalt-60? 100 grams = 50 grams = 3 50 grams = 5 grams h 5 grams = 1.5 grams h = 5.6 years Cut in half 3 times 8. Antimony-17 has a half-life of 3.85 days. How much of an 848 g sample of antimony-17 will be left after 3.0 hours? 3.85 days x 4 hours = 9.4 hours 1 day 3.0 hours = 0.35 hours (.5) 0.35 = grams 9. If the half-life of gold-198 is.696 days and you begin with 50.0 g sample of gold-198. After half-lives, how much of the radioactive isotope remains? 50(.5) = 1.5 grams remaining