Chapter 8 Chemical Bonding

Ionic q covalent bonds bonds 3 polarity and

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Unformatted text preview: Polarity and Electronegativity q Which bond in each set is most polar? Which qF2, HF qFCl, Cl2 qO2, BO Electronegativities F 4.0 O 3.5 Cl 3.0 C 2.5 H 2.1 B 2.0 qOH, CH, HH, HF 3 Which of the following is the most polar bond? 1. H2 2. 3. 4. HF HCl HI 0% 1 0% 0% 2 3 0% 4 3 8.5 Drawing Lewis Structures Procedure to ensure conformance to the octet rule: Procedure octet 1. Write an atomic skeleton 2. Count valence electrons 3. Place electron pairs between bonded atoms 4. Place remaining electrons on the outside atoms, 4. then the central atom then 5. Shift electrons, if necessary, from nonbonding 5. positions to bonding positions to make multiple bonds and satisfy the octet rule. bonds 6. Check to make should molecule has the correct 6. number of valence electrons and obeys the octet rule rule 3 Write Lewis formulas for the following molecules or ions: q SO2 q CO2 q CO32q SO32q H2SO4 q HCN q CNq NCS- 3 Group Work qWrite Lewis formulas for the Write following molecules or ions: following CO HNO3 NO3− Remember the octet rule! 3 Trends in Structures q What do the structures of the following What molecules have in common? molecules q CO32− q NO3− q SO3 4 Formal Charges q Assigning Formal Charges q For each atom, count the electrons in lone pairs and half For the electrons it shares with other atoms. the q Subtract that from the number of valence electrons for Subtract that atom: the difference is its formal charge. that 4 8.6 Resonance Structures q Lewis formulas Lewis don’t always accurately represent bonds. Sometimes it takes two (or more) formulas to adequately represent the bonds. represent 4 Resonance q How many different valid Lewis formulas How can you write for the following molecules or ions? How do they differ? ions? SO2 SO3 H2SO4 CO32- NO3- HNO3 NCSq The different resonance forms represent The delocalized bonding. delocalized 4 Which molecule would have the longest O-O bond length? Hint: Draw all possible forms Hint: of each molecule. of 1. O2 2. O3 3. H2O2 0% 1 0% 2 0% 3 4 8.7 Exceptions to t...
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