A. element B. atom C. electron D. molecule

1. 1. The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided? • element • atom • electron • molecule

2. 10 1. The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided? A. element B. atom C. electron D. molecule

3. 2. 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.

4. 10 2. 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.

5. 3. 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 14 grams of X to form the same compound? • 7 grams • 14 grams • 21 grams • 28 grams

6. 10 3. 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 14 grams of X to form the same compound? A. 7 grams B. 14 grams C. 21 grams D. 28 grams

7. 4. According to John Dalton’s observations, when elements combine in a compound, A. the ratio of their masses is always the same. B. each element contributes an equal number of atoms. C. their volumes are always equal. D. their masses are always equal.

8. 10 4. According to John Dalton’s observations, when elements combine in a compound, A. the ratio of their masses is always the same. B. each element contributes an equal number of atoms. C. their volumes are always equal. D. their masses are always equal.

9. 5. Which of the following is NOT part of John Dalton’s atomic theory? • All elements are composed of atoms. • All atoms of the same element have the same mass. • Atoms contain subatomic particles. • A compound contains atoms of more than one element.

10. 10 5. Which of the following is NOT part of John Dalton’s atomic theory? A. All elements are composed of atoms. B. All atoms of the same element have the same mass. C. Atoms contain subatomic particles. D. A compound contains atoms of more than one element.

11. 6. Which of the following most accurately represents John Dalton’s model of the atom? • a tiny, solid sphere with an unpredictable mass for a given element • a hollow sphere with a dense nucleus • a tiny, solid sphere with a predictable mass for a given element • a sphere that is hollow throughout

12. 10 6. 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

13. 7. 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.

14. 10 7. 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.

15. Figure 4-1

16. 8. The diagram in Figure 4-1 shows the results of Rutherford’s gold foil experiment. What caused some of the alpha particles to bounce straight back from the gold foil? • electrons in the gold atoms • negative charges in the gold atoms • other alpha particles • nuclei in the gold atoms

17. 10 8. The diagram in Figure 4-1 shows the results of Rutherford’s gold foil experiment. What caused some of the alpha particles to bounce straight back from the gold foil? A. electrons in the gold atoms B. negative charges in the gold atoms C. other alpha particles D. nuclei in the gold atoms

18. 9. Rutherford’s gold foil experiment provided evidence for which of the following statements? • Negative and positive charges are spread evenly throughout an atom. • Alpha particles have a positive charge. • Gold is not as dense as previously thought. • There is a dense, positively charged mass in the center of an atom.

19. 10 9. 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.

20. 10. Who provided evidence for the existence of a nucleus in an atom? • John Dalton • J. J. Thomson • Democritus • Ernest Rutherford

21. 10 10. Who provided evidence for the existence of a nucleus in an atom? A. John Dalton B. J. J. Thomson C. Democritus D. Ernest Rutherford

22. 11. In an atomic model that includes a nucleus, positive charge is • concentrated in the center of an atom. • spread evenly throughout an atom. • concentrated at multiple sites in an atom. • located in the space outside the nucleus.

23. 10 11. In an atomic model that includes a nucleus, positive charge is A. concentrated in the center of an atom. B. spread evenly throughout an atom. C. concentrated at multiple sites in an atom. D. located in the space outside the nucleus.

24. 12. 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.

25. 10 12. 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.

26. 13. Which subatomic particle has a negative charge? • electron • alpha particle • neutron • proton

27. 10 13. Which subatomic particle has a negative charge? A. electron B. alpha particle C. neutron D. proton

28. 14. Which statement about subatomic particles is NOT true? A. Protons and neutrons have almost the same mass. B. Protons and electrons have opposite charges. C. Unlike protons and electrons, neutrons have no charge. D. Protons and neutrons have the same charge.

29. 10 14. Which statement about subatomic particles is NOT true? A. Protons and neutrons have almost the same mass. B. Protons and electrons have opposite charges. C. Unlike protons and electrons, neutrons have no charge. D. Protons and neutrons have the same charge.

30. 15. 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.

31. 10 15. 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.

32. 16. Which of the following is unique for any given element? • the number of neutrons • the charge on the electrons • the number of protons • the mass of a neutron

33. 16. Which of the following is unique for any given element? • the number of neutrons • the charge on the electrons • the number of protons • the mass of a neutron

34. 17. The number of protons in one atom of an element is that element’s A. mass number. . B. balanced charge. C. atomic number D. isotope.

35. 18. To find the number of neutrons in an atom, you would subtract • mass number from atomic number. • atomic number from mass number. • atomic number from electron number. • isotope number from atomic number.

36. 19. Suppose an atom has a mass number of 23. Which statement is true beyond any doubt? A. The atom has an odd number of neutrons. B. The atomic number is less than 11. C. The atom is not an isotope. D. The number of protons in the nucleus does not equal the number of neutrons.

37. 20. 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.

38. 10 20. 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.

39. 21. In Niels Bohr’s model of the atom, electrons move • like balls rolling down a hill. • like planets orbiting the sun. • like popcorn in a popcorn popper. • like beach balls on water waves.

40. 10 21. In Niels Bohr’s model of the atom, electrons move A. like balls rolling down a hill. B. like planets orbiting the sun. C. like popcorn in a popcorn popper. D. like beach balls on water waves.

41. 22. What can you assume has happened if an electron moves to a higher energy level? • The atom has become more stable. • The electron has lost energy. • The electron has gained energy. • The atom has lost an electron.

42. 10 22. What can you assume has happened if an electron moves to a higher energy level? A. The atom has become more stable. B. The electron has lost energy. C. The electron has gained energy. D. The atom has lost an electron.

43. 23. How was Bohr’s atomic model similar to Rutherford’s model? • It assigned energy levels to electrons. • It described electron position in terms of the electron cloud model. • It described how electrons gain or lose energy. • It described a nucleus surrounded by a large volume of space.

44. 10 23. 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.

45. 24. 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.

46. 10 24. 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.

47. 25. What do scientists use to predict the locations of electrons in atoms? • Probability • algebra • geometry • ratios and proportions

48. 10 25. What do scientists use to predict the locations of electrons in atoms? A. probability B. algebra C. geometry D. ratios and proportions

49. 26. What does the electron cloud model describe? A. the most likely locations of electrons in atoms B. the precise locations of electrons in atoms C. the number of electrons in an atom D. the mass of the electrons in an atom

50. 10 26. What does the electron cloud model describe? A. the most likely locations of electrons in atoms B. the precise locations of electrons in atoms C. the number of electrons in an atom D. the mass of the electrons in an atom