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Name _____________________________________________ 4 Date ____________________ Class ____________________ The Structure of the Atom Objective 1 Section 4.1 Early Ideas About Matter In your textbook, read about the philosophers, John Dalton, and defining the atom. For each statement below, write true or false. ____________________ 1. Ancient philosophers regularly performed controlled experiments. ____________________ 2. Philosophers formulated explanations about the nature of matter based on their own experiences. ____________________ 3. Both Democritus and Dalton suggested that matter is made up of atoms. ____________________ 4. Dalton’s atomic theory stated that atoms separate, combine, or rearrange in chemical reactions. ____________________ 5. Dalton’s atomic theory stated that matter is mostly empty space. ____________________ 6. Dalton was correct in thinking that atoms could not be divided into smaller particles. ____________________ 7. Dalton’s atomic theory stated that atoms of different elements combine in simple whole-number ratios to form compounds. ____________________ 8. Dalton thought that all atoms of a specific element have the same mass. ____________________ 9. Democritus proposed that atoms are held together by chemical bonds, but no one believed him. ___________________ 10. Dalton’s atomic theory was based on careful measurements and extensive research. Section 4.2 Defining the Atom In your textbook, read about the electron and the nuclear atom. For each item in Column A, write the letter of the matching item in Column B. Column A Column B _________11. Proposed the nuclear atomic model a. Thomson _________12. Determined the mass-to-charge ratio of an electron b. Millikan _________13. Calculated the mass of an electron c. Rutherford Chemistry: Matter and Change 96 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Objective 2 In your textbook, read about the discovery of protons and neutrons. Complete the following table of proton, electron, and neutron characteristics. Particle Symbol Location Relative Charge Relative Mass 1. Proton 2. n 1/1840 3. Section 4.3 How Atoms Differ In your textbook, read about atomic number. For each statement below, write true or false. _____________________ 4. The number of neutrons in an atom is referred to as its atomic number. _____________________ 5. The periodic table is arranged by increasing atomic number. _____________________ 6. Atomic number is equal to the number of electrons in an atom. _____________________ 7. The number of protons in an atom identifies it as an atom of a particular element. _____________________ 8. Most atoms have either a positive or a negative charge. Answer the following questions. 9. Lead has an atomic number of 82. How many protons and electrons does lead have? ______________________________________________________________________________________________ 10. Oxygen has 8 electrons. How many protons does oxygen have? ____________________ 11. Zinc has 30 protons. What is its atomic number? ______________________ 12. Astatine has 85 protons. What is its atomic number? ______________________ 13. Rutherfordium has an atomic number of 104. How many protons and electrons does it have? ______________________________________________________________________________________________ 14. Polonium has an atomic number of 84. How many protons and electrons does it have? ______________________________________________________________________________________________ 15. Nobelium has an atomic number of 102. How many protons and electrons does it have? ______________________________________________________________________________________________ Chemistry: Matter and Change 99 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 In your textbook, read about isotopes and mass number. Determine the number of protons, electrons, and neutrons for each isotope described below. 16. An isotope has atomic number 19 and mass number 39. ______________________________________________________________________________________________ 17. An isotope has 14 electrons and a mass number of 28. ______________________________________________________________________________________________ 18. An isotope has 21 neutrons and a mass number of 40. ______________________________________________________________________________________________ 19. An isotope has an atomic number 51 and a mass number 123. ______________________________________________________________________________________________ Answer the following question. 20. Which of the isotopes in problems 13–16 are isotopes of the same element? Identify the element. ______________________________________________________________________________________________ Write each isotope below in symbolic notation. Use the periodic table to determine the atomic number of each isotope. 21. neon-22 ______________ 23. cesium-133 ______________ 22. helium ______________ 24. uranium-234 _______________ Label the mass number and the atomic number on the following isotope notation. 25. ___________________ 26. ___________________ Chemistry: Matter and Change 24 12 Mg 100 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Objective 3 Section 4.4 Unstable Nuclei and Radioactive Decay In your textbook, read about radioactivity. For each item in Column A, write the letter of the matching item in Column B. Column A ________ 1. Column B a. nuclear reaction The rays and particles that are emitted by a radioactive material ________ 2. A reaction that involves a change in an atom’s nucleus b. beta radiation ________ 3. The process in which an unstable nucleus loses energy spontaneously c. radiation d. radioactive decay ________ 4. Fast-moving electrons In your textbook, read about types of radiation. Use the diagram to answer the questions. 5. Which plate do the beta particles bend toward? Explain. ______________________________________________________________________________________________ 6. Explain why the gamma rays do not bend. ______________________________________________________________________________________________ 7. Explain why the path of the beta particles bends more than the path of the alpha particles. ______________________________________________________________________________________________ ______________________________________________________________________________________________ Complete the following table of the characteristics of alpha, beta, and gamma radiation. Radiation Type 8. Alpha 9. 10. Composition Symbol Mass (amu) Charge 1/1840 High-energy electromagnetic radiation Chemistry: Matter and Change 101 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Section 24.1 Nuclear Radiation In your textbook, read about the terms used to describe nuclear changes. Use each of the terms below just once to complete the passage. alpha particle radioactivity gamma ray radioisotope beta particles radiation X-ray radioactive decay The discovery of the (11) ___________________ in 1895 by Wilhelm Roentgen opened a whole new field of research. Among those who worked in this new field were Pierre and Marie Curie. The Curies discovered that some forms of matter give off (12) ________________, a combination of particles and energy. Marie Curie named this process (13) ________________ Another term used to describe the process by which one element spontaneously changes into another element is (14) ____________________. Any isotope that undergoes such changes is called a(n) (15)___________________. There are three common forms of radiation. One type is a form of energy known as (16) ________________. The other types of radiation consist of particles. The form of radiation containing the heavier particle is made up of helium nuclei called (17) ___________________. The form of radiation containing the lighter particle consists of electrons called (18) ____________________. Section 24.2 Radioactive Decay In your textbook, read about the changes that take place in an atomic nucleus when it decays. Circle the letter of the choice that best completes the statement. 19. The number of stable isotopes that exist compared to the number of unstable isotopes is a. much less. b. much more. c. slightly more. d. about the same. 20. The isotope formed by the beta decay of a. 18. 40 19 b. 39. 21. The isotope formed by the alpha decay of a. 234. 22. When the isotope a. 234 89 150 66 c. 20. 238 92 238 91 d. 21. U has a mass number of b. 236. c. 238. d. 240. Pa decays by beta emission, the isotope formed is Ac . b. 238 90 Th . 23. The isotope formed by the alpha decay of a. K has an atomic number of Dy . Chemistry: Matter and Change b. 150 67 Ho . 154 66 c. 237 92 U. d. 238 92 U. c. 150 64 Gd . d. 154 67 Ho . Dy is 97 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 24. The decay of a. 4 2 Section 162 69 Tm Tm yields He . 162 68 Er and b. e–. c. . d. e+ . 24.3 Nuclear Reactions In your textbook, read about the process of induced nuclear transmutation. For each statement below, write true or false. ___________________ 25. Transmutation is the conversion of an atom of one element to an atom of another element. ___________________ 26. All nuclear reactions involve some type of nuclear transmutation. ___________________ 27. Scientists induce transmutations by bombarding stable nuclei with highenergy alpha, beta, or gamma radiation. ___________________ 28. The half-life of a radioisotope is the time it takes for that isotope to decay. ___________________ 29. A radioisotope that decays very rapidly has a short half-life. ___________________ 30. Radioisotopes with very long half-lives are seldom found in Earth’s crust. ___________________ 31. Mass number and atomic number are conserved in all nuclear reactions. ___________________ 32. The mass of a 25.0 g piece of 3.1 g after 7.2 hr. Chemistry: Matter and Change 98 238 96 Cm (half-life: 2.4 hr) will be reduced to Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Objective 4 Average Atomic Mass In your textbook, read about mass of individual atoms. Circle the letter of the choice that best completes the statement. 1. The mass of an electron is a. smaller than the mass of a proton. b. smaller than the mass of a neutron. c. a tiny fraction of the mass of an atom. d. all of the above. 2. One atomic mass unit is a. 1/12 the mass of a carbon-12 atom. b. 1/16 the mass of an oxygen-16 atom. c. exactly the mass of one proton. d. approximately the mass of one proton plus one neutron. 3. The atomic mass of an atom is usually not a whole number because it accounts for a. only the relative abundance of the atom’s isotopes. b. only the mass of each of the atom’s isotopes. c. the mass of the atom’s electrons. d. both the relative abundance and the mass of each of the atom’s isotopes. Use the figures to answer the following questions. 4. What is the atomic number of osmium? _____________________ 5. What is the chemical symbol for niobium? _______________________ 6. What is the atomic mass of osmium? ____________________ 7. What units is the atomic mass reported in? ____________________ 8. How many protons and electrons does an osmium atom have? A niobium atom? ______________________________________________________________________________________________ Calculate the atomic mass of each element described below. Then use the periodic table to identify each element. 9. Isotope 63 65 Mass (amu) Percent Abundance X 62.930 69.17 X 64.928 30.83 Chemistry: Matter and Change 99 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 10. Isotope 35 37 Mass (amu) Percent Abundance X 34.969 75.77 X 36.966 24.23 Chemistry: Matter and Change 100 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Chemistry: Matter and Change 101 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Chemistry: Matter and Change 97 Study Guide Name ____________________________________________ Date ____________________ Class ___________________ 134 Chemistry: Matter and Change 98 Study Guide Name _____________________________________________ Date ____________________ Class ____________________ 4 Chemistry: Matter and Change 98 Study Guide