Chapter 4 Atomic Structure Chapter Test A Multiple Choice Write the letter that best answers the question or completes the statement on the line provided. 1. Democritus thought that matter was made of tiny particles a. of earth, air, fire, and water. b. that could not be divided. c. that could be divided. d. that were all round and smooth. 2. If 2 grams of element X combine with 4 grams of element Y to form compound XY, how many grams of element Y would combine with 12 grams of X to form the same compound? a. 6 grams b. 12 grams c. 18 grams d. 24 grams 3. Which of the following most accurately represents John Dalton s model of the atom? a. a tiny, solid sphere with an unpredictable mass for a given element b. a hollow sphere with a dense nucleus c. a tiny, solid sphere with a predictable mass for a given element d. a sphere that is hollow throughout 4. J.J. Thomson s experiments provided evidence that an atom a. is the smallest particle of matter. b. contains negatively charged particles. c. has a negative charge. d. has a positive charge. 5. Rutherford s gold foil experiment provided evidence for which of the following statements? a. Negative and positive charges are spread evenly throughout an atom. b. Alpha particles have a positive charge. c. Gold is not as dense as previously thought. d. There is a dense, positively charged mass in the center of an atom. 6. Which statement best describes Rutherford s model of the atom? a. It is like an avocado with the pit representing the nucleus. b. It is like an aquarium with swimming fish representing positive charges. c. It is like a fried egg with the yolk representing the nucleus. d. It is like a huge stadium with a positively charged marble at the center. Physical Science Chapter 4 Test A 25
Name Class Date 7. Which statement about subatomic particles is true? a. Protons, neutrons, and electrons all have about the same mass. b. Unlike protons or neutrons, electrons have no mass. c. Neutrons have no charge and no mass. d. An electron has far less mass than either a proton or neutron. 8. Which of the following is unique for any given element? a. the number of neutrons b. the charge on the electrons c. the number of protons d. the mass of a neutron 9. Suppose an atom has a mass number of 35. Which statement is true beyond any doubt? a. The atom has an odd number of neutrons. b. The atomic number is less than 17. c. The atom is not an isotope. d. The number of protons in the nucleus does not equal the number of neutrons. 10. Which statement is true about oxygen-17 and oxygen-18? a. They do not have the same number of protons. b. Their atoms have an identical mass. c. They are isotopes of oxygen. d. The have the same mass number. 11. How was Bohr s atomic model similar to Rutherford s model? a. It assigned energy levels to electrons. b. It described electron position in terms of the electron cloud model. c. It described how electrons gain or lose energy. d. It described a nucleus surrounded by a large volume of space. 12. Which statement accurately represents the arrangement of electrons in Bohr s atomic model? a. Electrons vibrate in fixed locations around the nucleus. b. Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level. c. Electrons travel around the nucleus in fixed energy levels with equal amounts of energy. d. Electrons travel randomly in the relatively large space outside the nucleus. 13. What do scientists use to predict the locations of electrons in atoms? a. probability b. algebra c. geometry d. ratios and proportions 26 Physical Science Chapter 4 Test A
14. Which statement about electrons and atomic orbitals is NOT true? a. An electron has the same amount of energy in all orbitals. b. An orbital can contain a maximum of two electrons. c. An electron cloud represents all the orbitals in an atom. d. An atom s lowest energy level has only one orbital. 15. The glowing of a neon light is caused by electrons emitting energy as they a. move from lower to higher energy levels. b. collide with other electrons. c. move from higher to lower energy levels. d. collide with the nucleus. Completion Complete each statement on the line provided. 1. Unlike Democritus, Aristotle did not believe that matter was composed of tiny, indivisible. 2. John Dalton observed that elements always combine in the same ratio to form a particular. Figure 4-1 3. In Rutherford s gold foil experiment, shown in Figure 4-1, alpha particles that bounce straight back from the foil have struck in the gold atoms. 4. The region in which an electron is most likely to be found is called a(an). 5. An atom in which an electron has moved to a higher energy level is in a(an) state. Physical Science Chapter 4 Test A 27
Name Class Date Short Answer Use complete sentences to write the answers to the questions on the lines provided. 1. What scientific word comes from a Greek word meaning uncut? Which Greek philosopher first used the word to describe matter? 2. If an atom of an element has a mass number of 31 and 16 neutrons in its nucleus, what is the atomic number of the element? 3. If an atom of germanium has a mass number of 70 and an atomic number of 32, how many neutrons are in its nucleus? 4. What did Bohr s model of the atom do that Rutherford s model did not? 5. How does the electron cloud model of the atom represent the locations of electrons in atoms? 28 Physical Science Chapter 4 Test A
Using Science Skills Use the diagram to answer each question. Write the answers on a separate sheet of paper. Figure 4-2 1. Analyzing Data What subatomic particles are represented in Figure 4-2? Assuming all the particles in the nucleus are visible, what are the atomic and mass numbers of the atom shown? 2. Inferring Would Dalton have recognized the model of a nucleus shown in Figure 4-2? Explain your answer. 3. Inferring Would Rutherford have recognized the model of a nucleus in Figure 4-2? Explain your answer. 4. Inferring Why do you think the proton was discovered before the neutron? (Hint: Consider the properties of protons and neutrons.) 5. Evaluating Is Figure 4-2 a useful model of an atom? Explain your answer. Essay Write the answer to each question on a separate sheet of paper. 1. Why did Rutherford propose a new model of the atom after seeing the results of the gold foil experiment? 2. A sample of calcium contains calcium-40, calcium-44, calcium-42, calcium-48, calcium-43, and calcium-46 atoms. Explain why these atoms can have different mass numbers, but they must have the same atomic number. 3. Why is Bohr s model of the atom often called the planetary model? 4. What is the difference between an orbital and the electron cloud? 5. Explain what the colors in a fireworks display reveal about the movement of electrons in atoms. Physical Science Chapter 4 Test A 29