Chemistry Chapter 6 Test Review

Transcription

1 Chemistry Chapter 6 Test Review Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together is called a(n) a. dipole. c. chemical bond. b. Lewis structure. d. London force. 2. The electrons involved in the formation of a chemical bond are called a. dipoles. c. Lewis electrons. b. s electrons. d. valence electrons. 3. The electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held together by a(n) a. chemical bond. c. neutron. b. London force. d. ion. 4. If two covalently bonded atoms are identical, the bond is a. nonpolar covalent. c. dipole covalent. b. polar covalent. d. coordinate covalent. 5. When atoms share electrons, the electrical attraction of an atom for the shared electrons is called the atom's a. electron affinity. c. resonance. b. electronegativity. d. hybridization. 6. If the atoms that share electrons have an unequal attraction for the electrons, the bond is called a. nonpolar. c. ionic. b. polar. d. dipolar. 7. What are shared in a covalent bond? a. ions c. electrons b. Lewis structures d. dipoles 8. Most chemical bonds are a. purely ionic. c. partly ionic and partly covalent. b. purely covalent. d. metallic. 9. The greater the electronegativity difference between two bonded atoms, the greater the percentage of in the bond. a. ionic character c. metallic character b. covalent character d. electron sharing 10. A bond that is less than 5% ionic is considered a. polar covalent. c. nonpolar covalent. b. ionic. d. metallic. 11. The B F bond in BF 3 (electronegativity for B is 2.0; electronegativity for F is 4.0) is a. polar covalent. c. nonpolar covalent. b. ionic. d. metallic. 12. The percentage ionic character and the type of bond in Br 2 (electronegativity for Br is 2.8) is

2 a. 0%; nonpolar covalent. c. 0%; pure ionic. b. 100%; polar covalent. d. 100%; pure ionic. 13. A neutral group of atoms held together by covalent bonds is a a. molecular formula. c. polyatomic ion. b. chemical formula. d. molecule. 14. Which of the following shows the types and numbers of atoms joined in a single molecule of a molecular compound? a. molecular formula c. covalent bond b. potential energy diagram d. ionic bond 15. Which of the following is not an example of a molecular formula? a. H 2 O c. NH 3 b. B d. O Bond length is the average distance between two bonded atoms a. at which potential energy is at a minimum. b. at which kinetic energy is at a maximum. c. at which potential energy is at a maximum. d. and equal to one-half the diameter of the electron cloud. 17. In a molecule of fluorine (F 2 ), the two shared electrons give each fluorine atom how many electron(s) in the outer energy level? a. 1 c. 8 b. 2 d The electron configuration of nitrogen is 1s 2 2s 2 2p 3. How many more electrons does nitrogen need to satisfy the octet rule? a. 1 c. 5 b. 3 d What group of elements satisfies the octet rule without forming compounds? a. halogen c. alkali metal b. noble gas d. alkaline-earth metal 20. In drawing a Lewis structure, each nonmetal atom except hydrogen should be surrounded by a. 2 electrons. c. 8 electrons. b. 4 electrons. d. 10 electrons. 21. To draw a Lewis structure, one must know the a. number of valence electrons in each atom. b. atomic mass of each atom. c. bond length of each atom. d. ionization energy of each atom. 22. After drawing a Lewis structure, one should a. determine the number of each type of atom in the molecule. b. add unshared pairs of electrons around nonmetal atoms. c. confirm that the total number of valence electrons used equals the number available. d. determine the electronegativity of each atom. 23. What is the correct Lewis structure for hydrogen chloride, HCl?

3 a. A c. C b. B d. D 24. Bonding in molecules or ions that cannot be correctly represented by a single Lewis structure is a. polyatomic. c. single bonding. b. resonance. d. double bonding. 25. The chemical formula for water, a covalent compound, is H 2 O. This formula is an example of a(n) a. formula unit. c. ionic formula. b. Lewis structure. d. molecular formula. 26. The ions in most ionic compounds are organized into a a. molecule. c. polyatomic ion. b. Lewis structure. d. crystal. 27. The lattice energy is a measure of the a. strength of an ionic bond. c. strength of a covalent bond. b. strength of a metallic bond. d. net charge on a crystal. 28. Compared with ionic compounds, molecular compounds a. have higher boiling points. c. have lower melting points. b. are brittle. d. are harder. 29. The forces of attraction between molecules in a molecular compound are a. stronger than the forces among formula units in ionic bonding. b. weaker than the forces among formula units in ionic bonding. c. approximately equal to the forces among formula units in ionic bonding. d. zero. 30. Ionic compounds are brittle because the strong attractive forces a. allow the layers to shift easily. b. cause the compound to vaporize easily. c. keep the surface dull. d. hold the layers in relatively fixed positions. 31. The properties of both ionic and molecular compounds are related to the a. lattice energies of the compounds. b. strengths of attraction between the particles in the compounds. c. number of covalent bonds each contains. d. mobile electrons that they contain. 32. How many extra electrons are in the Lewis structure of the phosphate ion, PO 3 4? a. 0 c. 3 b. 2 d A chemical bond formed by the attraction between positive ions and surrounding mobile electrons is a(n) a. nonpolar covalent bond. c. polar covalent bond. b. ionic bond. d. metallic bond. 34. In metals, the valence electrons a. are attached to particular positive ions. c. are immobile.

4 b. are shared by all of the atoms. d. form covalent bonds. 35. In metallic bonds, the mobile electrons surrounding the positive ions are called a(n) a. Lewis structure. c. electron cloud. b. electron sea. d. dipole. 36. The shiny appearance of a metal is most closely related to the metal's a. highly mobile valence electrons. c. brittle crystalline structure. b. covalent bonds. d. positive ions. 37. As light strikes the surface of a metal, the electrons in the electron sea a. allow the light to pass through. b. become attached to particular positive ions. c. fall to lower energy levels. d. absorb and re-emit the light. 38. If a material can be shaped or extended by physical pressure, such as hammering, which property does the material have? a. conductivity c. ductility b. malleability d. luster 39. Which best explains the observation that metals are malleable and ionic crystals are brittle? a. their chemical bonds c. their enthalpies of vaporization b. their London forces d. their net change 40. Malleability and ductility are characteristic of substances with a. covalent bonds. c. Lewis structures. b. ionic bonds. d. metallic bonds. 41. According to VSEPR theory, an AB 2 molecule is a. trigonal-planar. c. linear. b. tetrahedral. d. octahedral. 42. VSEPR theory is a model for predicting a. the strength of metallic bonds. c. lattice energy values. b. the shape of molecules. d. ionization energy. 43. The concept that electrostatic repulsion between electron pairs surrounding an atom causes these pairs to be separated as far as possible is the foundation of a. VSEPR theory. c. the electron-sea model. b. the hybridization model. d. Lewis theory. 44. According to VSEPR theory, the shape of an AB 3 molecule is a. trigonal-planar. c. linear. b. tetrahedral. d. bent. 45. According to VSEPR theory, the structure of the ammonia molecule, NH 3, is a. trigonal-planar. c. trigonal-pyramidal. b. bent. d. tetrahedral. 46. Use VSEPR theory to predict the shape of the hydrogen chloride molecule, HCl. a. tetrahedral c. bent b. linear d. trigonal-planar

5 47. Use VSEPR theory to predict the shape of the carbon tetraiodide molecule, CI 4. a. tetrahedral c. bent b. linear d. trigonal-planar 48. Use VSEPR theory to predict the shape of the chlorate ion, ClO 3. a. trigonal-planar c. trigonal-pyramidal b. octahedral d. bent 49. Use VSEPR theory to predict the shape of carbon dioxide, CO 2. a. tetrahedral c. bent b. linear d. octahedral 50. The mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies is called a. VSEPR theory. c. hybridization. b. malleability. d. dipole-dipole interaction. 51. The strong forces of attraction between the positive and negative regions of molecules are called a. dipole-dipole forces. c. lattice forces. b. London forces. d. orbital forces. 52. Compared with molecular bonds, the strength of intermolecular forces is a. weaker. c. about the same. b. stronger. d. too variable to compare. 53. The equal but opposite charges present in the two regions of a polar molecule create a(n) a. electron sea. c. crystal lattice. b. dipole. d. ionic bond. 54. The reason the boiling point of water (H 2 O) is higher than the boiling point of hydrogen sulfide (H 2 S) is partially explained by a. London forces. c. ionic bonding. b. covalent bonding. d. hydrogen bonding. 55. A polar molecule contains a. ions. b. a region of positive charge and a region of negative charge. c. only London forces. d. no bonds. 56. When a polar molecule attracts the electron in a nonpolar molecule, a. a dipole is induced. c. an ionic bond forms. b. a crystal lattice forms. d. a Lewis structure forms. Short Answer 1. Explain why scientists use resonance structures to represent some molecules.

6 2. Differentiate between an ionic compound and a molecular compound. 3. Explain why metals are good conductors of electricity. Problem 1. Draw a Lewis structure for the oxalate ion, C 2 O Draw a Lewis structure for carbon disulfide, CS 2.

7 3. Draw a Lewis structure for the nitrate ion,. Use VSEPR theory to predict its molecular geometry. Essay 1. How many different kinds of covalent bonds can a nitrogen atom form? Explain.