Bent linear trigonal planar trigonal pyramidal Polar nonpolar nonpolar polar Sp 3 sp sp 2 sp 3

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1 Name period ap chemistry unit 3 worksheet 1. What are structural isomers? Draw two isomers of pentane. Compounds with the same formula but different structures. See in class 2. give the formula for each of the following a. pentane C 5H 12 c. 2Hexene C 6H 12 e. 1butyne C 4H 6 g. benzene C 6H 6 b. heptane C 7H 16 d. proponol C 3H 7OH f. ethane C 2H 6 h. methane CH 4 3. The molecules BF 3 and SO 3 are both trigonal planar. Does this information completely define the bond angles of these molecules? No, double bonds take up more space so the bond angle will be slightly less than List the molecular shapes which are always polar. Bent, trigonal pyramidal, see saw, tshaped, square pyramidal 5. Give the molecular geometry, bond angles, and polarity for each of the following molecules a. Cl 2O b. N 2O c. SO 3 d. SO 3 2 Bent linear trigonal planar trigonal pyramidal Polar nonpolar nonpolar polar Sp 3 sp sp 2 sp 3 e. ICl 2 f. PF 5 g. ICl 3 h. CO 3 2 linear trigonal bipyramidal Tshaped trigonal planar , Nonpolar nonpolar polar nonpolar sp 2 i.sf 6 j. TeF 4 k. ClO 3 l. PBr 3 octahedral seesaw trigonal pyramidal trigonal pyramidal 90 90, Nonpolar polar polar polar sp 3 sp 3 6. The molecules NF 3, BF 3, and ClF 3 all have the same molecular formulas of the type XF 3, but the molecules have different geometries. Predict the shape of each and explain the origin of the differing shapes. NF 3: trigonal pyramidal : one lone pair BF 3: trigonal planar: no lone pairs ClF 3: Tshaped: 2 lone pairs 7. The three species NH 2, NH 3, and NH 4 + have HNH bond angles of 105, 107, and 109 respectively. Explain the variation in bond angles. 105 has two lone pairs on the central atom 107 has one lone pair on the central atom 109 has no lone pairs on the central atom 8. Tell the hybrid orbitals used in each molecule in question 3 (you do not need to do expanded octets) See above

2 9. Give the approximate value for the indicated bond angles and tell the hybrid orbitals used in the following molecules a. c. HOClO HCOH <109.5 <<109.5 b. d. HC=CH HCOCH Predict whether the following molecules possess dipole moments a. HCN b. BF 3 c. XeF 4 d. CCl What is the difference between a sigma and pi bond? Which is generally stronger? Sigma: overlap is between nuclei Pi: overlap is above and below nuclei Sigma are generally stronger 12. If an atom uses an sp 2 hybrid orbital, how many unhybridized p orbitals in the same valence shell remain on the atom? How many pi bonds can the atom form? a. Draw the Lewis structure for methane and formaldehyde, H 2CO. see in class b. What is the hybridization at the carbon atoms for each? Sp 3 and sp 2 c. The carbon atom in methane cannot participate in multiple bonding, whereas that in formaldehyde can. Explain this observation. All of the p orbitals have been hybridized in methane, but in formaldehyde, there is a left over p orbital that can create a pi bond 14. Acetone has the following Lewis structure: a. What is the total number of valence electrons in the molecule? 24 b. How many valence electrons are used for sigma bonds? 18 c. How many valence electrons are used for pi bonds? 2 d. How many valence electrons remain in nonbonding pairs in the molecule? 4 e. What is the hybridization at the central carbon atom of the molecule? Sp a.draw the structure for acetic acid: see in class b. What is the molecular geometry around each carbon atom? Tetrahedral, trigonal planar

3 c. What type of hybrid orbitals does each carbon have? sp 3, sp Name three elements which... a) cannot have expanded octets when it is the central atom in a molecule. C, N, O b) do not need an octet to form stable compounds. H, Be, B 17. Is the pi bond in NO 2 localized or delocalized? How do you know? Delocalized. There is resonance 18. How many sigma bonds and pi bonds does each of the following molecules have? a. b. 10 sigma and 3 pi 9 sigma and 9 pi 19. What type of intermolecular forces operates between a. All molecules London dispersion b. Polar molecules dipoledipole c. The hydrogen of a polar bond and a nearby small, very electronegative atom? Hydrogen bonding 20. Put the following in order of increasing polarizability : GeCl 4, CH 4, SiCl 4, SiH 4, GeBr 4 CH 4, SiH 4, SiCl 4, GeCl 4, GeBr What kind of attractive forces must be overcome to a. Boil water hydrogen bonding and London dispersion b. Melt KCl ionic bonds c. Sublime I 2 london dispersion d. Boil H 2S dipole dipole and London dispersion 22. The dipole moments of HCl and HI are 1.08 D and 0.44 D respectively a. Which of these substances will have the greater dipoledipole interaction? HCl b. Which of these substances will have the greater London dispersion forces? HI 23. Boiling point Substance Suggest a reason why CH 3CN has a higher 231 K C 3H 8 boiling point than C 3H K CH 3CN It is polar and the C 3H 8 is nonpolar 24. Nitrogen and carbon monoxide have almost equal masses. Explain why the boiling point of carbon monoxide is slightly higher than that of nitrogen Carbon monoxide is more polarizable and so the London dispersion forces are stronger

4 25. Which member of the following pairs of substances would you expect to have a higher boiling point? a. N 2 or O 2 b. CH 4 or SiH 4 c. NaCl or CH 3Cl d. CH 3Cl or CH Put the following in order of increasing boiling points: CO 2, O 2, BaCl 2, H 2O, H 2S O 2, CO 2, H 2S, H 2O, BaCl Which of the following has the fewest pi bonds and is nonpolar? a.hcch b.co 2 c.co 3 2 d.n 2 e.so A student places a mixture of plastic beads consisting of polypropylene (PP) and polyvinyl chloride (PVC) in a 1.0 L beaker containing distilled water. After stirring the contents of the beaker vigorously, the student observes that the beads of one type of plastic sink to the bottom of the beaker and the beads of the other type of plastic float on the water. The chemical structures of PP and PVC are represented by the diagrams below, which show segments of each polymer. a. Given that the spacing between polymer chains in PP and PVC is similar, the beads that sink are made of which polymer? Explain. The PVC beads sink. The spacing between chains is similar, but a Cl atom has a greater mass than CH 3 (b) The boiling point of liquid propene (226 K) is lower than the boiling point of liquid vinyl chloride (260 K). Account for this difference in terms of the types and strengths of intermolecular forces present in each liquid. Both substances have dipoledipole interactions and London dispersion forces (or propene is essentially nonpolar with only LDFs while vinyl chloride has both LDFs and dipoledipole forces). Propene contains a CH 3 group, but vinyl chloride contains a Cl atom. Vinyl chloride thus has a larger electron cloud, is more polarizable, and has a larger dipole moment. Thus intermolecular attractions are stronger in vinyl chloride, which results in it having the higher boiling point. Review 29. Write the noble gas configuration for the following a. Sn b. Cr c. Fe 2+ d. Ag [Kr]5s 2 4d 10 5p 2 [Ar]4s 1 3d 5 [Ar]3d 6 [Kr]5s 2 4d a. How many molecules are in 5.63 g of methane? 2.11 x molecules b. How many hydrogen atoms are in 5.63 g of methane? 8.47 x hydrogen atoms c. How many moles are in 14.5 g of aluminum sulfate? mol d. What is the molar mass of iron(iii) hydroxide? g/mol e. How many grams are in 3.20 moles of potassium sulfide? 353 g

5 31. Complete the following table Symbol # of neutrons # of protons # of electrons Atomic # Mass # Ba Mn Au Ca Substance E has 29 protons, 28 electrons, and 34 neutrons. Substance F has 29 protons, 27 electrons, and 34 neutrons. Substances E and F can be categorized as A) different elements B) ions C) isotopes D) nuclides E) nucleons 20. A 0.144g sample of a hydrocarbon is analyzed by combustion analysis, g of carbon dioxide and g of water is produced. Find the empirical formula of the hydrocarbon. C 2H Which is a list of elements listed in order of increasing ionization energy? A) Na, K, Rb B) Ne, Ar, Kr C) Al, Mg, Na D) Br, Cl, F E) O, S, Se 22. Which property generally increases down a group but decreases from left to right a. Melting point b. electronegativity c. ionization energy d. atomic radius 23. What is the nuclear charge for the following atoms a. Na b. F c. Sn d. P e. Ar Which of the following explains why oxygen atoms, in their ground state, are paramagnetic? a. Pauli exclusion principle b. electron shielding c. Hund s rule d. aufbau principle 25. How many valence electrons does nitrogen have? An atom has the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 2. How many valence electrons does this atom have? Which atom will have the largest radius in each pair. a. K, Na b. Na, Na + c. Br, Br d. K, B