Nuclear and Quantum Chemistry

Name: ________ANSWER KEY__________________________ Date: ___________________________ Period: ________ Unit 5 Test Study Guide Nuclear & Quantum Chemistry Nuclear Equations Write nuclear equations for the following scenarios: 1. Alpha emission by plutonium‐239, one of the substances formed in nuclear power plants. Pu  He + 2. U Beta decay by sodium‐24, used to detect blood clots Na  e+ Mg 3. Oxygen‐15 undergoes positron emission, used to assess the efficiency of the lungs. Pu  He + N 4. Copper‐64 goes through electron capture, used to diagnose lung disease. Cu + e Zn 5. A radioactive isotope is bombarded with an alpha particle to produce Polonium‐209. Pb + He  Po 6. A silver‐117 undergoes three beta emissions before it reaches a stable nuclide. What is the final product? Ag e+ e+ e+ Sn Complete the following nuclear equations and identify which type of nuclear decay it is. 7. Sr  Y ++ e This is ___beta decay____________. 8. F  O ++ e This is ___positron emission_______________. 9. 10. Rn  F++ Po + He e 11. U  He + 12. Xe  13. Sr + I ++ e  O This is ___alpha decay______________. This is ____electron capture____________. Th e Bi This is ____alpha decay______________. This is positron emission. This is ____electron capture______________. Radioactivity & Half‐Lives 14. One of the radioactive nuclides formed in nuclear power plants is hydrogen‐3, called tritium, which has a half‐ life of 12.26 years. How long before a sample decreases to 1/8 of its original amount? 1  ½  ¼  1/8 3 half lives x 12.26 = 36.78 years 15. Uranium‐238 is one of the radioactive nuclides sometimes found in soil. It has a half‐life of 454 years. What percentage of a sample is left after 2270 years? 100%  50  25  12.5  6.25% 2270 / 454 = 4 half lives 16. Cesium‐133, which is used in radiation therapy, has a half‐life of 30 years. What was the size of the original sample if after 120 years you now have 16.0 grams? 120/30 = 4 half lives ______  ____  _____  _____  16.0 grams Work backwards! 256 grams 17. Phosphorus‐32, which is used for leukemia therapy, has decayed to 1/16th of its original amount in 42.9 days. What is the half‐life of phosphorous‐32? 1  ½  ¼  1/8  1/16 4 half lives 42.9/4 = 10.7 days 18. Iodine has a half‐life of 8.07 days. Assuming you start with 90.5 grams, how much of the sample (in mg) would you have left after 24.21 days? 24.21/8.07 = 3 half lives 90.5  45.25  22.625  11.3 grams Bohr Model Diagrams In the Bohr model diagrams show below, indicate the number of protons (p) and neutrons (n) in the nucleus of each atom. Write the number of electrons (e) on each energy level. Not all energy levels will be used for every element. 19. (a.) silicon‐30 Silicon has 4 valence e- (b.) calcium‐41 8e 8e- P = 14 N = 16 2e- 4e- P = 20 N = 21 Calcium has 2 valence e- - 2e- 10e- Electromagnetic Spectrum 20. List the seven colors of the visible spectrum from shortest to longest wavelength. violet, indigo, blue, green, yellow, orange, red 21. What is the wavelength range of visible light? 400 nm to 700 nm. 22. Draw your interpretation of a long wavelength (above the time frame) and a short wavelength (below the time frame). Indicate which has higher frequency and higher energy.  23. 10 second time frame  (a) Which has a longer wavelength, orange or blue? orange (b) Which has a lower frequency, green or red? red (c) Which has more energy, indigo or yellow? indigo Quantum Mechanics Explain each of the following rules or terms associated with quantum mechanics. 24. Hund’s Rule electrons will avoid pairing if orbitals of equal energy are available, ex: one electron in each p orbital before two. 25. Aufbau Principle electrons will fill orbitals from low to high energy 26. Pauli Exclusion Principle no two electrons can be in the same place at the same time, can’t have the same four quantum numbers, ex: snowflakes 27. Hesisenberg’s Uncertainty Principle can’t know both the position and velocity of an electron, can only estimate 28. orbital region of space that indicates the likelihood of where an e‐ might be: s has 1, p has 3, d has 5, etc. Each orbital holds 2 electrons 29. identify the four quantum numbers energy level, sublevel‐shape, which orbital within the sublevel, spin Orbital Diagrams Draw the orbital diagrams (boxes and arrows) for each of the following elements. 30. silicon 31. zinc Electron Configuration 32. Identify the element described by each electron configuration. (a.) 1s22s22p63s2 magnesium (Mg) (b.) 1s22s22p63s23p64s23d104p65s24d3 niobium (Nb) (c.) 1s22s22p63s23p64s23d8 nickel (Ni) (d.) [Kr] 5s24d6 ruthenium (Ru) (e.) [Ar]4s23d104p4 selenium (Se) Electron Configuration Continued 33. 34. Write the full electron configuration for the following atoms/ions (do NOT use the Noble Gas shortcut method). (a.) P 1s22s22p63s23p3 (b.) Y 1s22s22p63s23p64s23d104p65s24d1 (c.) Ca+2 1s22s22p63s23p6 (d.) Br‐ 1s22s22p63s23p64s23d104p6 Write the Noble Gas (shortcut) electron configuration for each of the following. (a.) Te [Kr]5s24d105p4 (b.) Sb [Kr]5s24d105p3 (c.) Bi [Xe]6s24f145d106p3 Relating Bohr’s Diagram and Electron Configurations to the Quantum Numbers 35. Which quantum number tells you the main energy level? n = principle quantum number = row in the periodic table 46. In the atom, 1s22s22p4 – what is the highest every level that holds an electron? 2 47. How many orbitals are in the p‐sublevel? 3 How many electrons? 6 48. How many orbitals are in the d‐sublevel? 5 How many electrons? 10 49. Which quantum mechanical principle states that (choose from Pauli Exclusion Principle, Aufbau Principle, and Hund’s Rule): (a) electrons will fill orbitals from lowest to highest energy? Aufbau Principle (b) no two electrons can have the same set of quantum numbers? Pauli exclusion principle (c) electrons will avoid pairing in an orbital if an orbital of equal energy is available? (the sharing rule) Hund’s Rule 40. How many electrons can be accommodated in each of the following: (a) one d orbital 2 (b) a set of f orbitals 14 (d) the 7s orbital 2 (c) the n = 4 shell 32 (e) one p orbital 2 Important Vocabulary & Concepts to review Define the following words Trajectory path followed by an electron quantum quantum world‐ small particles quantum mechanics – math associated with electrons quantum numbers – description of location of electron with highest energy in an atom entail include valence electrons electrons in the outermost shell, with highest energy, most likely to react frequency rate at which something occurs Wavelength distance between tops of a wave, red is the longest at 700nm, violet is the shortest at 400nm Explain the following concepts (you can use words and pictures) 1. Nuclear decay ANSWERS WILL VARY 2. Radioactivity 3. Radioactive particle 4. Half‐Life 5. Fission 6. Fusion 7. Electron orbital diagram 8. Electron configuration 9. Bohr model of the atom 10. The relationship between wavelength, frequency and energy 11. The relationship between energy levels, sublevels and orbitals 12. The relationship between an element’s electron configuration & its position on the periodic table