Chapter 4 - Exercises - Page 197c: 34

a, b, d, and f are polar; c and e are nonpolar.

a. HOCN (Isocyanic acid) Lewis Structure: H–O–C≡N H bonded to O O single bonded to C C triple bonded to N Polarity: Polar - Asymmetrical structure with highly electronegative atoms (O and N) at opposite ends - Net dipole moment due to uneven electron distribution b. COS (Carbonyl sulfide) Lewis Structure: O=C=S C double bonded to O C single bonded to S Geometry: Linear Polarity: Polar - Despite linear shape, O is more electronegative than S - Dipole does not cancel out c. XeF₂ (Xenon difluoride) Lewis Structure: F–Xe–F with three lone pairs on Xe Geometry: Linear (due to 5 electron domains: 2 bonding, 3 lone pairs) Polarity: Nonpolar Symmetrical linear shape cancels dipoles from F atoms d. CF₂Cl₂ (Dichlorodifluoromethane) Lewis Structure: Central C bonded to 2 F and 2 Cl atoms Geometry: Tetrahedral Polarity: Polar - Asymmetrical distribution of electronegative atoms (F and Cl) - Net dipole moment due to uneven electron pull e. SeF₆ (Selenium hexafluoride) Lewis Structure: Central Se bonded to 6 F atoms Geometry: Octahedral Polarity: Nonpolar - Symmetrical geometry cancels dipoles from identical F atoms f. H₂CO (Formaldehyde) Lewis Structure: H–C=O with another H bonded to C Geometry: Trigonal planar around C Polarity: Polar C=O bond is highly polar Asymmetrical shape leads to net dipole moment a. HOCN (exists as HO-CN) Lewis structure: H-O-C≡N This molecule is polar because the electronegativity difference between the atoms is significant, and the molecule has an asymmetric shape (bent) due to the presence of a lone pair on the oxygen atom. b. COS Lewis structure: C=O-S This molecule is polar because the electronegativity difference between the atoms is significant, and the molecule has an asymmetric shape due to the different atoms attached to the central carbon atom. c. XeF2 Lewis structure: F-Xe-F This molecule is nonpolar because the molecule has a symmetric, linear shape, and the two fluorine atoms have equal and opposite dipole moments, resulting in a net zero dipole moment. d. CF2Cl2 Lewis structure: Cl-C-Cl | F | F This molecule is nonpolar because the two chlorine atoms and the two fluorine atoms have equal and opposite dipole moments, resulting in a net zero dipole moment. e. SeF6 Lewis structure: F-Se-F | F | F | F This molecule is nonpolar because the molecule has a symmetric, octahedral shape, and the six fluorine atoms have equal and opposite dipole moments, resulting in a net zero dipole moment. f. H2CO (C is the central atom) Lewis structure: H-C-H || O This molecule is polar because the electronegativity difference between the atoms is significant, and the molecule has an asymmetric shape (bent) due to the presence of a lone pair on the oxygen atom.