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Test Review Chapters 4 and 25 Honors Chemistry Answers 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. ____Rutherford__________ Discovered the proton _____Goldstein__________ Discovered the charged nucleus (small) is the center with 99.9% of the atom as empty space where the electrons reside. ______Rutherford_______ Used an “oil drop” experiment to discover the charge and mass of an electron. ___Millikan__ Proposed the “Plum Pudding” model of the atom. _____Thomson________ Used the word “atomos” to describe matter. _____Democritos________ Called the “Father of Modern Chemistry”. ___Lavoisier_________ Discovered the neutron. _____Chadwick___________ Created the first atomic theory based on experimental evidence. _______Dalton_______ Discovered the electron. ______Thomson________ Discovered the nucleus. ____Rutherford_________ Discovered the Law of Conservation of Mass. ____Lavoisier_________ Proposed a model of the atom as a hard, indivisible sphere. _____Dalton______ Conducted experiments with cathode rays. ____Thomson_________ Know the 5 points of Dalton’s atomic theory and how two of those points have been changed! 1. All matter is made of atoms. 2. All atoms of the same element are exactly the same. Atoms of different elements are different. CHANGE – ATOMS OF THE SAME ELEMENT CAN HAVE DIFFERENT MASSES (ISOTOPES) 3. Atoms are indivisible. CHANGE – SUBATOMIC PARTICLES (PROTONS, NEUTRONS, ELECTRONS) 4. Atoms of different elements combine in whole number ratios to form compounds. 5. In chemical reactions, atoms are either combined, separated, or rearranged. 2. Fill in the following chart for the isotopes: Isotope Name Atomic Number (Z) Mass Number (A) Number of protons Number of neutrons Number of electrons 25 55 25 30 21 62 155 62 93 62 Sb 51 121 51 70 51 O-2 8 18 8 10 10 Symbol Manganese – 55 55 25 Mn+4 Samarium – 155 155 Antimony – 121 121 Oxide – 18 18 62 Sm 51 8 3. The most common isotopes of chromium are listed below. What is the average atomic mass of chromium? 52.02 amu 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 4. Element X is a soft, silvery-white metal that has two common isotopes, X and X. If the abundance 85 87 of X is 72.2% and the abundance of X is 27.8%, what is the average atomic mass of X? What is element X? 85.6 amu, Rb 5. Silicon has three naturally occurring isotopes. What is the average atomic mass of silicon? 28.09 amu 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? 3.35 x 1021 atoms 7. What is the mass of 0.44 moles of carbon? 5.3 g 8. How many atoms does 43.25 g of iron contain? 4.662 x 1023 atoms 9. If a student weighs out 2.01 g of silicon, how many moles is that? 0.0716 moles 10. How many moles are there in 2.4010 x 1025 particles of gold? 39.884 moles 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) 60.5 g 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? 5.1 cm3 What is the cylinder’s diameter if it is 1.2 cm in height? 1.2 cm 13. Convert 2950 micrograms to kilograms. 2.95 x 10-6 kg 14. Change 0.00014 hectoliters to nanoliters. 1.4 x 107 nL 15. Write the symbols for an alpha particle, beta particle, and gamma ray. Alpha particle – 42He; -1 0ß; Beta particle - Gamma particle – 00γ 16. When a nuclei undergoes alpha decay, how does the mass number change? Decreases by 4 17. During beta decay, describe what happens to the atomic number of the element. Increases by 1 18. What is the most penetrating form of radioactive particles? What can stop this form of radioactivity? Gamma rays, several meters of concrete or several centimeters of lead does not fully stop it 19. Write the equations for the reaction when the following undergo alpha decay: a. 235U b. 241Am c. 212At d. seaborgium-263 (Sg) 92 a. 235 95 4 U 92 c. 212 He + 231 2 4 At 85 Th 85 b. 90 4 Am 95 He + 208Bi 2 241 d. 83 263 He + 237Np 2 4 Sg 106 93 He + 259Rf 2 104 20. Write the equations for the reactions when the following undergo beta decay: a. 66Cu b. 84Br c. oxygen-18 d. 29 a. 66 35 0 Cu 29 c. 18 B + 66Zn -1 0 O 8 96 b. 30 84 d. 9 0 B + 84Kr -1 36 Br 35 B + 18F -1 244 0 Cm 96 B + 244 Bk -1 97 21. Write the equation showing the following isotopes undergoing gamma decay: a. Radium-218 (Ra) a. γ + 218Ra 218 0 88 0 Ra 88 244 b. Uranium-239 (U) b. 239 U 92 γ + 239U 0 0 92 Cm 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? 10.9 g 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? 32 g 24. How much strontium-90 will remain after 4 half-lives if the initial amount is 4.0 g? 0.25 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? 3.04 g