Test Bank for Fundamentals of General Organic and Biological Chemistry 7th Edition by McMurry Sample Chapter Molecular Compounds Diff: Section: 4.1 1 A) atomic B) covalent C) hydrogen D) ionic E) molecular 2) A chemical bond formed when two atoms share two pairs of electrons is a bond; it is best described as A) double; covalent B) double; ionic C) single; covalent D) single; ionic E) triple; covalent Answer: A Diff: Section: 4.1 3) Which representation of a hydrogen molecule is not correct? A) H=H B) H2 C) H:H E) none of the above Answer: A Diff: Section: 4.2 4) Which representation of a methane molecule is not correct? (A methane molecule is composed of one carbon atom and four hydrogen atoms.) A) CH4 B) C) D) E) none of the above Answer: D Diff: Section: 4.2 5) Which element is most likely to form three covalent bonds? A) C B) Si C) P D) S E) Se Answer: C Diff: Section: 4.2 6) In a covalent compound the bond length can be defined as A) the distance between any two pairs of electrons B) the distance between the two largest atoms C) the distance between two nuclei when the repulsion is greatest D) the distance between two nuclei when the attraction is greatest E) the distance between two nuclei when repulsion and attraction are balanced Answer: E Diff: Section: 4.2 7) Which group contains only elements which normally exist as diatomic molecules? A) nitrogen; sulfur, bromine B) helium; neon, argon C) nitrogen; oxygen, fluorine D) hydrogen; lithium, sodium E) oxygen; phosphorus, germanium Answer: C Diff: Section: 4.2 8) A chemical bond formed when two atoms share one pair of electrons is a bond; it is best described as A) double; covalent B) double; ionic C) single; covalent D) single; ionic E) triple; covalent Answer: C Diff: Section: 4.2 9) For the dot structure shown the most likely elements are X = and Y = A) carbon; hydrogen B) carbon; fluorine C) carbon; oxygen D) hydrogen; carbon E) fluorine; carbon Answer: B Diff: Section: 4.2 10) When two atoms share one or more pairs of electrons, a covalent bond is formed Answer: TRUE Diff: Section: 4.2 11) When a non-metal atom bonds with another non-metal atom, an ionic bond is formed Answer: FALSE Diff: Section: 4.2 12) Which point identifies the bond length between the two atoms of the diatomic molecule whose potential energy is shown on the graph? Answer: C Diff: Section: 4.2 13) Which point identifies the maximum repulsion between the two atoms of the diatomic molecule whose potential energy is shown in the graph? Answer: A Diff: Section: 4.2 14) Which element is most likely to be “X” in the diatomic molecule shown? A) nitrogen B) oxygen C) fluorine D) hydrogen E) helium Answer: B Diff: Section: 4.3 15) Which group in the Periodic Table is most likely to contain the element X in the molecule whose dot structure is shown? A) 2A B) 3A C) 4A D) 5A E) 6A Answer: E Diff: Section: 4.3 16) A chemical bond formed when two atoms share three pairs of electrons is a bond; it is best described as A) double; covalent B) single; covalent C) triple; covalent D) double; ionic E) triple; ionic Answer: C Diff: Section: 4.3 17) A triple bond involves the sharing of pairs of electrons between the atoms A) B) C) D) E) Answer: C Diff: Section: 4.3 18) A chemical bond formed when two atoms share six electrons is a bond; it is best described as A) double; covalent B) double; ionic C) single; covalent D) single; ionic E) triple; covalent Answer: E Diff: Section: 4.3 19) For the structure shown, the most likely elements are X = and Y = A) carbon; oxygen B) carbon; hydrogen C) nitrogen; oxygen D) oxygen; carbon E) oxygen; hydrogen Answer: D Diff: Section: 4.3 20) The element in the list given that is most likely to form a coordinate covalent bond is A) H B) C C) K D) Fe E) Ca Answer: D Diff: Section: 4.4 21) The smallest possible unit of a covalent compound is a(an) A) atom B) cation C) formula unit D) molecule E) polyatomic ion Answer: D Diff: Section: 4.5 22) The covalent bonding model is most useful in describing which of the following compounds? A) CoCl2 B) MgCl2 C) NiCl2 D) SCl2 E) none of the above Answer: D Diff: Section: 4.5 23) Which property could describe a covalent compound? A) It conducts electricity when melted B) It is a gas at room temperature C) It is composed of a non-metal and a metal D) It conducts electricity when dissolved in water E) none of the above Answer: B Diff: Section: 4.5 24) Which set of properties would identify an unknown white solid as a molecular compound? Contains a metal Has a definite crystal structure III Dissolves in water, but not in organic liquids Melts at 80 degrees Celsius Does not conduct electricity when melted A) I, II, III B) I, III, V C) II, III, IV D) II, IV, V E) I, IV, V Answer: D Diff: Section: 4.5 25) Which property is most closely associated with covalent molecules? A) It is a gas at room temperature B) It conducts electricity when dissolved in water C) It has a very high melting point D) It is composed of a metal and a nonmetal E) none of these Answer: A Diff: Section: 4.5 26) Covalent compounds form distinct molecules, and therefore may exist as gases, liquids, or solids at room temperature, depending on the characteristics of the compound Answer: TRUE Diff: Section: 4.5 27) In a Lewis dot structure the electrons which complete an octet but are not located between two atoms are referred to as A) bonding pairs B) delta minus electrons Diff: Section: 4.7 33) A molecule in which the central atom has no lone pairs and forms four single bonds is said to have a shape A) bent B) linear C) planar D) pyramidal E) tetrahedral Answer: E Diff: Section: 4.8 34) The molecule SiCl4 has a shape A) bent B) linear C) planar D) pyramidal E) tetrahedral Answer: E Diff: Section: 4.8 35) A molecule in which the central atom forms three single bonds and has one lone pair is said to have a shape A) bent B) linear C) planar D) pyramidal E) tetrahedral Answer: D Diff: Section: 4.8 36) A molecule in which the central atom forms one double bond and two single bonds is said to have a shape A) bent B) linear C) trigonal planar D) pyramidal E) tetrahedral Answer: C Diff: Section: 4.8 37) What is the molecular geometry of PH3? A) linear B) trigonal planar C) tetrahedral D) bent E) trigonal pyramidal Answer: E Diff: Section: 4.8 38) How many double bonds are there in a molecule of SF2? A) B) C) D) E) Answer: A Diff: Section: 4.8 39) According to VSEPR theory, a molecule with three charge clouds including one lone pair would have a shape A) bent B) linear C) tetrahedral D) trigonal planar t E) pyramidal Answer: A Diff: Section: 4.8 40) The water molecule has a geometry because its central atom has bonds and lone pairs of electrons A) bent; two; two B) linear; two; two C) pyramidal; three; one D) tetrahedral; four; zero E) planar triangular; three; one Answer: A Diff: Section: 4.8 41) Draw the Lewis structure for CCl4 What is the molecular geometry of this compound? Is the molecule polar or nonpolar? Answer: tetrahedral, non-polar Diff: Section: 4.7, 4.8 42) The bond angle in the molecule H2S is because the 109 110 111 112 113 A) exactly 109.5°; S atom has four charge clouds B) greater than 109.5°; lone pairs allow the bond angle to expand C) less than 109.5°; lone pairs force the hydrogen atoms closer together D) exactly 120°; lone pairs are counted as one charge cloud E) exactly 180°; the S atom has two bonds Answer: C Diff: Section: 4.8 43) Which of the following molecules has a CCH bond angle of 180°? A) HCCH B) H2CCH2 C) H3CCH3 D) H3CCHO E) none of them Answer: A Diff: Section: 4.8 44) Which element listed is the least electronegative? A) nitrogen B) hydrogen C) oxygen D) fluorine E) chlorine Answer: B Diff: Section: 4.9 45) Which element listed is the most electronegative? A) aluminum B) bromine C) chlorine D) iodine E) sodium Answer: C Diff: Section: 4.9 46) A section of the Periodic Table containing main group elements is shown Which bond would be least polar? A) WX B) YZ C) WZ D) WY E) cannot be determined without more specific information Answer: E Diff: Section: 4.9 47) A section of the Periodic Table containing main group elements is shown If the elements W, X, Y, and Z have electronegativity values of 1.0, 2.0, 2.5, and 3.5, respectively, which bond is the least polar? A) WX B) WZ C) XY D) XZ E) YZ Answer: C Diff: Section: 4.9 48) A section of the Periodic Table containing main group elements is shown If the elements W, X, Y, and Z have electronegativity values of 1.0, 2.0, 2.5, and 3.5, respectively, which bond is ionic? A) WY B) WZ C) XY D) XZ E) YZ Answer: B Diff: Section: 4.9 49) A bond where the electrons are shared equally is called a(an) bond A) polar covalent B) coordinate covalent C) nonpolar covalent D) ionic E) none of the above Answer: C Diff: Section: 4.9 50) A bond where the electrons are shared unequally is called a(an) bond A) polar covalent B) coordinate covalent C) nonpolar covalent D) ionic E) none of the above Answer: A Diff: Section: 4.9 51) Consider the molecule SiCl4 The electronegativity values for Si and Cl are 1.8 and 3.0, respectively Based on these values and on consideration of molecular geometry, the Si-Cl bond is and the molecule is A) polar; polar B) nonpolar; nonpolar C) polar; nonpolar D) nonpolar; polar E) none of the above Answer: C Diff: Section: 4.10 52) The carbon dioxide molecule is linear The electronegativities of C and O are 2.5 and 3.5, respectively Based on these values and on consideration of molecular geometry, the C-O bond is and the molecule is A) polar; polar B) nonpolar; nonpolar C) polar; nonpolar D) nonpolar; polar E) none of the above Answer: C Diff: Section: 4.10 53) Consider a bent molecule, such as H2Se, in which the central atom has two lone pairs of electrons The electronegativities of H and Se are 2.1 and 2.4, respectively Based on these values and on consideration of molecular geometry, the HSe bond can be considered almost and the molecule is A) polar; polar B) nonpolar; nonpolar C) polar; nonpolar D) nonpolar; polar E) none of the above Answer: D Diff: Section: 4.10 54) The VSEPR model or molecular structure requires a knowledge of to predict the geometry of an atom in a molecule A) the number of atoms bonded to the atom of interest B) the total number of atoms in the molecule C) the number of electron pairs on the atom of interest D) both A and C E) none of the above Answer: D Diff: Section: 4.10 55) A molecule that contains three identical polar bonds to the central atom will be A) nonpolar if the geometry is planar triangular B) polar in all cases C) nonpolar in all cases D) impossible to tell the polarity E) either polar or nonpolar depending on the identity of the atoms bonded to the central atom Answer: A Diff: Section: 4.10 56) Explain how it is possible for CCl4 to have polar bonds but be a non-polar molecule A diagram may be helpful in your answer, but it must be explained Answer: (This question could also be asked about CF4 or CO2.) The bonds in this compound are polar due to the difference in their electronegativity values However, the molecule is not polar because the molecule is symmetrical, which means that the polar forces in different directions balance each other out In this case, the overall distribution of electrons in the molecule is even Diff: Section: 4.10 57) What is the systematic name of ICl3? A) iodine chloride B) iodine(III) chloride C) triiodine chloride D) iodine trichloride E) tri(iodine chloride) Answer: D Diff: Section: 4.11 58) The formula for phosphorus pentafluoride is A) PhF5 B) PF5 C) P5F D) (PF)5 E) P5F5 Answer: B Diff: Section: 4.11 59) Although noble gases not normally form covalent compounds, XeO3 has been prepared The systematic name of this compound is A) trioxy xenon B) trixenon trioxide C) xenon trioxide D) xenon(III) oxide E) none of the above Answer: C Diff: Section: 4.11 60) The formula for sulfur hexabromide is A) SF6 B) SBr6 C) SBr4 D) SiBr6 E) SiB6 Answer: B Diff: Section: 4.11 61) The formula for carbon disulfide is A) CS2 B) C2S C) CSi2 D) CaS2 E) (CS)2 Answer: A Diff: Section: 4.11 62) If SiCl4 is named as a covalent compound, what would it be called? A) silicon chloride B) chlorosilicate C) silicon tetrachloride D) sulfur chloride E) sulfur tetrachloride Answer: C Diff: Section: 4.11 63) The compound BrF3 would be called A) boron trifluoride B) triboron fluoride C) tri (bromine fluoride) D) tribromine fluoride E) bromine trifluoride Answer: E Diff: Section: 4.11 Match the following A) OF2 B) BrF5 D) N2O4 E) SF6 F) CO G) ICl H) SO2 I) CH4 J) IF7 10 K) PCI3 11 L) NH3 64) iodine heptafluoride Diff: Section: 4.10 65) oxygen difluoride Diff: Section: 4.10 C) CCI4 66) dinitrogen tetroxide Diff: Section: 4.10 67) bromine pentafluoride Diff: Section: 4.10 68) ammonia Diff: Section: 4.10 69) carbon tetrachloride Diff: Section: 4.10 70) phosphorus trichloride Diff: Section: 4.10 71) carbon monoxide Diff: Section: 4.10 72) sulfur hexafluoride Diff: Section: 4.10 73) sulfur dioxide Diff: Section: 4.10 74) methane Diff: Section: 4.10 75) iodine monochloride Diff: Section: 4.10 Answers: 64) J 65) A 66) D 67) B 68) L 69) C 70) K 71) F 72) E 73) H 74) I 75) G