Consider the following three atoms: Ar (protons = 18, neutrons = 21, atomic mass = 38.964313 u), K (protons = 19, neutrons = 20, atomic mass = 38.963707 u), and Ca (protons = 20, neutrons = 19, atomic mass = 38.970719 u). Which one is stable? How will the others decay? Will any of these nuclei decay by electron capture but not by B+ decay?

1) Complete the following nuclear fission reaction of thorium-232. 232Th + n → 99Kr + 124Xe +      ?      a) 4He b) 10B c) 10n d) 11n  e) 11B  2) Calculate the energy released in the reaction. The atomic masses are 232Th = 232.038051 u, 99Kr = 98.957606 u, and 124Xe = 123.905894 u. (Express your answer to five significant figures).

b) Complete the following decay reaction by identifying both the temporary nucleus (??) and the end product (?) that it decays into. In this case, sodium-23 is bombarded with protons, forming a short-lived nucleus which quickly undergoes alpha decay. 2Na+H → (??) → (⁄?) + ª Enter the chemical symbol for the temporary nucleus: Enter the mass number for the end product, A = Enter the atomic number for the end product, Z = Enter the chemical symbol for the end product: AV A/ AV 10

Once again, the final products have less mass than the 2 nuclei that fuse together; find the missing mass that converts to energy in the last reaction. Using the numbers in the Atomic Mass column, calculate 3He + 3He H-H- 4He. Type the entire calculator answer carefully. [it should be positive, similar in style to 0.012179] (1) Atomic (2) Element (3) Symbol (4) Mass (5) % Abundance (or Radioactive Decay Mode) (7) Half-life (if radioactive) Atomic Number Number, Mass 0. (Neutron) 1.008665 10.4 min Hydrogen Deuterium Tritium H. 99.985% 0.015% 1.007825 2.014102 T. 1 3 3.016049 12.33 yr Helium Не 0.000137% 99.999863% 3 3.016029 4. 4.002602 3. Lithium Li 6.015121 7.016003 7.5% 92.5% 4 Beryllium EC, 7 100% Be 7.016928 53.29 days 9.012182 67 9

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The uranium decay series from U-238 to stable lead (Pb-206) is: U → Th → *Pa → U → 0Th → Ra → Rn → 18Th → Pb → Bi 238U 234TH 226 → Po 92 92 210Pb → 210 Bi → 210P0 → 206Pb 83 84 Of the 15 nuclei from U-238 to Pb-206, list those radionuclides that are alpha-particle emitters, and those that are beta-particle emitters. State your reasons.

Cobalt-60 undergoes beta minus decay. Determine the daughter nucleus and compare the calculated binding energy per nucleon of the parent and daughter nuclei. mass (Co-60) = 59.933817 u mass (daughter) = 59.930786 u

Uranium-235 decays spontaneously by nucleon emission. a) Write a balanced equation to show the decay of Uranium-235, 2U, that leads to the formation of Uranium- 235 234 and name all the particles involved b) Write a balanced equation to show the decay of Uranium-235, U, that leads to the formation of 92 Thorium-231. Name all the particles involved.

Determine the nucleus density (in kg/m³) of the following four isotopes. 4He (m= 4.00260325415 u) 40 Ar (m 39.9623831225 u) 179TI (m 178.99109 u) 232U (m 232.0371562 u)