Name __________________________________ Test Review Chemistry Unit 2: The Atom 1. Fill in the blank with the name of the historical person associated with the reference. Some names will be used more than once. James Chadwick John Dalton Democritos Eugene Goldstein Antoine Lavoisier Robert Millikan Ernst Rutherford JJ Thomson Used the famous “gold foil” experiment. _________________________________ Discovered the proton _____________________________ Discovered the charged nucleus (small) is the center with 99.9% of the atom as empty space where the electrons reside. _____________________________ Used an “oil drop” experiment to discover the charge and mass of an electron. __________________ Proposed the “Plum Pudding” model of the atom. ___________________________ Used the word “atomos” to describe matter. __________________________ Called the “Father of Modern Chemistry”. _________________________ Discovered the neutron. _______________________________ Created the first atomic theory based on experimental evidence. ___________________________ Discovered the electron. __________________________ Discovered the nucleus. ___________________________ Discovered the Law of Conservation of Mass. __________________________ Proposed a model of the atom as a hard, indivisible sphere. ________________________ Conducted experiments with cathode rays. ____________________________ Know the 5 points of Dalton’s atomic theory and how two of those points have been changed! 2. Fill in the following chart for the isotopes: Isotope/Ion Name Symbol Atomic Number (Z) Mass Number (A) Number of protons Number of neutrons Number of electrons 25 30 21 155 62 18 10 Antimony – 121 8 3. The most common isotopes of chromium are listed below. What is the average atomic mass of chromium? Isotope Chromium – 50 Chromium – 52 Chromium – 53 Chromium – 54 Mass (amu) 49.9460 51.9405 52.9406 54.0022 Percent Abundance 4.55% 81.75% 9.81% 3.89% 85 87 85 4. Element X is a soft, silvery-white metal that has two common isotopes, X and X. If the abundance of X is 87 72.2% and the abundance of X is 27.8%, what is the average atomic mass of X? What is element X? 5. Silicon has three naturally occurring isotopes. What is the average atomic mass of silicon? Isotope Name Silicon-28 Silicon-29 Silicon-30 Isotope Mass (amu) 27.98 28.98 29.97 Relative Abundance (%) 92.21 4.70 3.09 6. How many atoms is 0.00556 moles of barium? 7. What is the mass of 0.44 moles of carbon? 8. How many atoms does 43.25 g of iron contain? 9. If a student weighs out 2.01 g of silicon, how many moles is that? 10. How many moles are there in 2.4010 x 1025 particles of gold? 11. What is the mass of a block of aluminum that has a volume of 22.4 cm3? (Density of Al = 2.70 g/cm3) 12. If a metal cylinder of copper (density = 8.9 g/cm3) has a mass of 45.4 grams, what is the volume of the cylinder? What is the cylinder’s diameter if it is 1.2 cm in height? 13. Convert 2950 micrograms to kilograms. 14. Change 0.00014 hectoliters to nanoliters. 15. Write the symbols for an alpha particle, beta particle, and gamma ray. 16. When a nuclei undergoes alpha decay, how does the mass number change? 17. During beta decay, describe what happens to the atomic number of the element. 18. What is the most penetrating form of radioactive particles? What can stop this form of radioactivity? 19. Write the equations for the reaction when the following undergo alpha decay: a. 235U b. 241Am c. 212At d. seaborgium-263 (Sg) 92 95 85 20. Write the equations for the reactions when the following undergo beta decay: a. 66Cu b. 84Br c. oxygen-18 d. 29 35 244 Cm 96 21. Write the equation showing the following isotopes undergoing gamma decay: a. Radium-218 (Ra) b. Uranium-239 (U) 22. If the half-life for the radioactive decay of zirconium-84 is 26 minutes and I start with a 175 gram sample, how much will be left over after 104 minutes? 23. Mercury -197 is used for kidney scans and has a half-life of 3 days. If the amount of mercury-197 needed for a study is 1.0 gram and the time allowed for shipment is 15 days, how much mercury-197 will need to be ordered? 24. How much strontium-90 will remain after 4 half-lives if the initial amount is 4.0 g? 25. Iodine-131 is used to destroy thyroid tissue in the treatment of an overactive thyroid. The half-life of iodine-131 is 8 days. If a hospital receives a shipment of 550. g of iodine-131, how much I-131 would remain after 60 days?