122 CHAPTER 5ID 15. Which of the following best describes the particle-level bonding in a crystal of KBr? iupil doiw (A) alternating positive and negative metal ions in a crystal lattice framework. (B) positive and negative ions in fixed position in a crystal lattice framework. (C) mobile valence electrons shared between positive metal ions. (D) metallic and nonmetallic atoms covalently bonded in a 3-dimenional framework. () HO (C) CC (D) CH'OE Questions 16-17 use the following information. 6801 9010 oloegsini doidW8 H H H---H H H Ethane wolod a (B) но-с-Сн, — СH, — СH, — СH, ннн нннн H-C-C- C-C-C-C-C-H || | | I|| Η Η Η Η | H. нн Heptane Pentanoic Acid 10 Name Chemical Formula Molar Mass (g/mole) Boiling Point (°C) Ethane 30.07 -88.5 Heptane 16 100.20 98.1-98.7 Pentanoic Acid 102.13 186-187 16. Heptane and pentanoic acid have very similar molar masses, but pentanoic acid has a significantly higher boiling point. Which of the following statements best helps explain this observation? (A) The sum of the bond energies in heptane is lower than the sum of the bond energies in pentanoic acid. (B) There are more opportunities for London dispersion forces in heptane than in pentanoic acid. (C) There are more opportunities for hydrogen bonding in pentanoic acid than there are in heptane. (D) The carbon chains in heptane are farther apart than they are in heptane. quo

16. What is the molecular geometry of PH3? (A) Trigonal planar (B) T-shaped (C) Trigonal pyramidal (D) Tetrahedral 17. The correct Lewis structure for BF3 would have exactly: (A) 1 double bond (B) 2 double bonds (C) No double bonds (D) 1 triple bond 18. Nitrogen has a greater first ionization energy than phosphorus. What is the best evidence to support this observation? (A) Nitrogen has a greater effective nuclear charge. (B) A nitrogen atom is larger than a phosphorus atom. (C) The electron ionized from nitrogen is in a lower energy level closer to the nucleus. (D) The electron ionized from nitrogen is not from a valence energy level.

. For each of the following, draw the Lewis structure, predict the ONO bond angle, and give the hybridization of the nitrogen. You may wish to review the chapters on chemical bonding and advanced theories of covalent bonding for relevant examples. (a) NO2           (b) NO-2

For each pair, choose the compound with the higher lattice en-ergy , and explain your choice: (a) CaO or CaS; (b) BaO or SrO

5. Use Periodic table to answer the following: (a) Which has higher ionization potential Cs or Li? Why? (b) Arrange the following elements in increasing order of valence electrons, Ca, Rb, Br and Xe.

Quartz crystals are made of silicon dioxide. What is the molecular geometry of silicon dioxide? (*hint* sketch the molecule before answering) O Linear O Bent O Trigonal Pyramidal O Tetrahedral

The sulfate ion can be represented with four S—O bonds orwith two S—O and two S=O bonds. (a) Which representation is better from the stand point of formal charges? (b) What is theshape of the sulfate ion, and what hybrid orbitals of S are postu-lated for the σ bonding? (c) In view of the answer to part (b),what orbitals of S must be used for the π bonds? What orbitalsof O? (d) Draw a diagram to show how one atomic orbital fromS and one from O overlap to form a π bond.

What are the electron-pair geometry and the molecular structure of each of the following molecules or ions?(a) ClF5(b) ClO2−(c) TeCl42−(d) PCl3(e) SeF4(f) PH2−

Which substance in each of the following pairs would you expect to have the higher boiling point? (a) Ne or Xe, (b) CO2 or CS2, (c) CH4 or Cl2, (d) F2 or LiF, (e) NH3 or PH3 (a) Ne; (b) CS2; (c) CH4; (d) F2 ; (e) NH3 (a) Xe; (b) CS2; (c) Cl2; (d) LiF ; (e) PH3 O (a) Xe; (b) CS2; (c) Cl2; (d) LiF ; (e) NH3 (a) Xe; (b) CS2; (c) Cl2; (d) F2 ; (e) NH3 (a) Xe; (b) C02; (c) CH4 ; (d) LiF ; (e) PH3

3. Consider [Fe(H2O)]Cl;. The bonding between iron(III) and water is best described as: (a) metallic (b) ionic (c) covalent (d) coordinate covalent