Chapter 7 Practice Worksheet. Covalent Bonds and Molecular Structure

Name: __KEY_________________ Section: ____________ Chapter 7 Practice Worksheet: Covalent Bonds and Molecular Structure 1) How are ionic bonds and covalent bonds different? Ionic bonds result from the transfer of electrons from one atom to another; Covalent bonds result from two atoms sharing electrons. 2) Describe the relationship between the length of a bond and the strength of that bond. Strength of a bond increases as the bond gets shorter (inverse relationship) 3) Identify the type(s) of bond(s) found in the following molecules: a. CCl4 ___covalent________________________ b. Li2O ___ionic________________________ c. NF3 ___covalent________________________ d. CaSO4 ___ionic and covalent________________________ e. SO2 ___covalent________________________ f. Mg(OH)2 ___ionic and covalent________________________ 4) Define electronegativity. Electronegativity is the ability for an atom in a molecule to attract electrons to itself. 5) Use electronegativity values to place the following elements in increasing order: F, N, H, P, Si, C, O Si < H = P ≈ C < N < O < F 6) Determine if the bond between atoms in each example below is nonpolar covalent, polar covalent, or ionic. a. H2 ___npc____________ e. NF __pc______________ b. PCl ___pc_____________ f. MgO __ionic____________ c. F2 ___npc____________ g. CH __npc_____________ d. NaBr ___ionic__________ h. HCl __pc______________ page 1 of 5 Name: __KEY_________________ Section: ____________ 7) Draw Lewis Structures for the following molecules: (the descriptions below indicate the number and types of bonds on central atoms (first one listed except in H2O; outer atoms have complete octets with lone pairs) a. CO2 (double bonds from C to j. NF3 (3 single bonds, 1 lone pair) each O, no lone pairs) b. BeCl2 (single bond to each Cl, no lone pairs) c. H2O (single bond to O, 2 lone pairs on O) d. BF3 (single bonds to F, no lone pairs) e. CCl4 (single bonds to Cl, no lone pairs) f. NH3 (single bonds to H, 1 lone k. CO (triple bond, lone pair on C and O) l. O3 (1 single bond, 1 double bond, 1 lone pair) m. CO32- (2 single bonds, 1 double bond) n. SO2 (1 single bond, 1 double bond, 1 lone pair) o. PF5 (5 single bonds, no lone pairs) pair on N) g. NO3- (2 single bonds, 1 double bond, no lone pairs) h. SO3 (2 single bonds, 1 double p. PCl5 (5 single bonds, no lone pairs) q. SF6 (6 single bonds, no lone pairs) bond, no lone pairs) i. SO32- (3 single bonds, 1 lone pair) r. TeF6 (6 single bonds, no lone pairs) 8) Which of the above compounds (in number 7) require resonance structures to describe the structure properly? Draw them. g, h, l, m, and n page 2 of 5 Name: __KEY_________________ Section: ____________ 9) Which of the above compounds (in number 7) are exceptions to the octet rule? b, d, o, p, q, r 10) Fill in the table below to determine the molecular geometry for the following molecules: Formula ABE formula Number of edomains on central atom # e- domains/ # non-bonding domains on central atom ElectronDomain Geometry (name) Molecular Geometry (name) Bond angle(s) on central atom CO2 AB2 2 2/0 Linear Linear 180o BeCl2 AB2 2 2/0 Linear Linear 180o H2 O AB2E2 4 2/2 Tetrahedral Bent <109.5o BF3 AB3 3 3/0 Trigonal planar Trigonal planar 120o CCl4 AB4 4 4/0 Tetrahedral Tetrahedral 109.5o NH3 AB3E1 4 3/1 Tetrahedral Trigonal pyramidal <109.5o NO3- AB3 3 3/0 Trigonal planar Trigonal planar 120o SO3 AB3 3 3/0 Trigonal planar Trigonal planar 120o SO32- AB3E1 4 3/1 Tetrahedral Trigonal pyramidal <109.5o NF3 AB3E1 3 3/1 Tetrahedral Trigonal pyramidal <109.5o page 3 of 5 Name: __KEY____________________ Section: _______________ # e- domains/ # non-bonding domains on central atom ElectronDomain Geometry Molecular Geometry (name) Bond angle(s) on central atom Formula ABE formula Number of edomains on central atom CO AB1E1 2 1/1 Linear Linear 180o O3 AB2E1 3 2/1 Trigonal planar Bent <120o CO32- AB3 3 3/0 Trigonal planar Trigonal planar 120o SO2 AB2E1 3 2/1 Trigonal planar Bent <120o PF5 AB5 5 5/0 Trigonal bipyramidal Trigonal 120o and 90o bipyramidal PCl5 AB5 5 5/0 Trigonal bipyramidal Trigonal 120o and 90o bipyramidal SF6 AB6 6 6/0 Octahedral Octahedral 90o TeF6 AB6 6 6/0 Octahedral Octahedral 90o 11) a. Identify the molecules in the table above that are polar. H2O, NH3, SO32-, NF3, CO, O3, SO2 b. How many nonbonding pairs of electrons did the polar molecules have? __1 or 2________ c. How many nonbonding pairs of electrons did the nonpolar molecules have? __none_______ 12) Give one example of a polar molecule that has nonpolar bonds. ___O3____________ Give one example of a nonpolar molecule that has polar bonds. ___CCl4____________ page 4 of 5 Name: __KEY____________________ Section: _______________ 13) Indicate the hybridization of the central atom. Also indicate the total number of sigma (σ σ) and pi (π π) bonds in the following molecules. Formula Hybridization of central atom # of σ bonds # of π bonds CO2 sp 2 2 BeCl2 sp 2 0 H2 O sp3 2 0 BF3 sp2 3 0 CCl4 sp3 4 0 NH3 sp3 3 0 NO3- sp2 3 1 SO3 sp2 3 1 SO32- sp3 3 0 NF3 sp3 3 0 CO sp 1 2 O3 sp2 2 1 CO32- sp2 3 1 SO2 sp2 2 1 PF5 sp3d 5 0 PCl5 sp3d 5 0 SF6 sp3d2 6 0 TeF6 sp3d2 6 0 page 5 of 5