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Name:____________________________ Date:___________ Period:____ Review Chemistry I Unit 3: Atomic Theory and Structure Define each of the following terms: 1. atom: 2. proton: 3. electron: 4. neutron: 5. nucleus: 6. atomic number: 7. mass number: 8. isotope: 9. average atomic mass: 10. Avogadro constant: 11. molar mass: Circle or write in the correct answer: 12. Which of the following was originally a part of Dalton's atomic theory, but had to be revised later based on new experimental evidence? (circle all that apply) A. B. C. D. Atoms are tiny indivisible particles. Atoms of the same element are identical. Atoms of different elements can sometimes be identical. Compounds are made by combining atoms. 13. Consider J.J. Thomson’s cathode ray tube experiment. Briefly describe what occurred that gave evidence of electrons in all atoms. ___________________________________________________________________ ___________________________________________________________________ 1 14. Which of the following is FALSE about subatomic particles? A. B. C. D. Electrons are negatively charged and are the lightest subatomic particle. Protons are positively charged and have nearly the same mass as neutrons. Neutrons have no charge and have no mass. The mass of a neutron nearly equals the mass of a proton. 15. All atoms are neutral because the number of __________________ always equals the number of __________________ in every atom. Fill in the chart with a charge and mass: Proton Neutron Electron Charge (+ , – , or 0 ) Mass (1 or 0) ____ ____ ____ ____ ____ ____ Rutherford Gold Foil Experiment gold atom expected results gold atom actual results 16. What observations in this experiment by Rutherford led to the theory that atoms are mostly empty space, and that almost all of the mass of the atom is contained in a tiny, dense nucleus? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ 17. Based on Rutherford’s discovery of the nucleus, which model of the atom is thought to be true? A. B. C. D. Protons, electrons, and neutrons are evenly distributed throughout the atom. The nucleus is made of protons, electrons, and neutrons. Electrons are located around the nucleus and occupy most of the volume. The nucleus is made of electrons and protons. 2 18. All atoms of the same element have the same ____. A. B. C. D. number of neutrons number of protons mass numbers mass 19. What are atoms of the same element with different numbers of neutrons? A. B. C. D. ions atoms numbers of electrons isotopes 20. Explain why isotopes of the same element are not considered different elements. ___________________________________________________________________ ___________________________________________________________________ 75 35X 21. Element X has an atomic number of 35 and a mass number of 75. How many of each subatomic particle are in a neutral atom of the element? A. B. C. D. 35 protons, 35 neutrons, and 70 electrons 35 protons, 75 neutrons, and 35 electrons 75 protons, 35 neutrons, and 40 electrons 35 protons, 40 neutrons, and 35 electrons 22. In which of the following is the number of neutrons correctly represented? A. F has 9 neutrons. B. As has 108 neutrons. C. Mg has 12 neutrons. D. U has 238 neutrons. 23. The weighted average atomic mass of the element chlorine is 35.45 amu, but the mass number of a chlorine-37 atom is 37. So how is the average atomic mass of an element different from the mass number of an atom? ___________________________________________________________________ ___________________________________________________________________ 24. Which of the following statements about atoms is FALSE? A. B. C. D. Atoms of the same element can have different masses. Isotopes of an element have different numbers of protons. The nucleus of an atom has a positive charge. Atoms are mostly empty space. 3 25. Which of the following statements about atoms and subatomic particles is FALSE? A. B. C. D. Protons have a positive charge. Electrons are negatively charged and have a mass of 1. The nucleus of an atom is positively charged. Neutrons are located in the nucleus of an atom. 26. 15 moles of sodium and 15 moles of carbon have the same number of _________. A. B. C. D. atoms grams molecules ALL of the above Calculations and Mole Conversions SHOW ALL WORK BOX your answer atom ↔ mole 27. Convert 4.50 moles of Fe to atoms of Fe. 28. Convert 4.03 x 1022 atoms of He to moles of He. 4 Calculations and Mole Conversions SHOW ALL WORK BOX your answer gram ↔ mole 29. Convert 0.300 moles of S to grams of S. 30. Convert 324 grams of tin (Sn) to moles of Sn. additional practice 31. How many atoms are in 1.85 mol Pb? 32. How many moles is 2.12 x 1024 atoms of carbon? 5 KEY Unit 3 Review - Regular 12. A, B 13. Every element released negatively charge cathode rays that bent toward a positive plate. 14. C 15. protons, electrons proton +1 1 neutron 0 1 electron –1 0 16. Most of the alpha particles traveled through the gold atoms showing atoms are mostly empty space. Very few positively charged alpha particles deflected revealing a tiny, dense, positive region in atoms. 17. C 18. B 19. D 20. They are isotopes b/c they have different numbers of neutrons, but they are the same element b/c they have the same number of protons (same atomic number). 21. D 22. C 23. Average atomic mass is a “weighted” average of all atoms of an element that depends on the relative abundance (amount) of each isotope of an element, but mass number is just the number of protons and neutrons in one single atom of an element. 24. B 25. B 26. A 27. 2.71 x 1024 atoms Fe 28. 0.0669 mol He 29. 9.62 g S 30. 2.73 mol Sn 31. 1.11 x 1024 atoms Pb 32. 3.52 mol C 6