L13S10_CovalentBond_Resonance%2002-19-10

L13S10_CovalentBond_Resonance%2002-19-10 - L 13:...

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Unformatted text preview: L 13: "Covalent Bonding, Resonance, Formal Charge 2/17/2010 Lewis Electron Dot Structures Valence Electrons Stable Octet Previously :: : : : Ionic Bonding (Electron Transfer) (Electron e- + - - Coulomb :: ::: : + :F: . . . Li. Be . .B . . C . .N . : O . : F. :Ne : . . . . . . Na. Mg . .Al . .Si . . . . :S . : Cl . :Ar: P . . :: : : : :: © 2000 A.Pines M.Kubinec UCB L3-1 H . He : Attraction Covalent Bonding (Electron Sharing) (Electron Molecular Orbitals :: :: Li. + : F. Li + + Na. + : Cl. © 2000 A.Pines M.Kubinec UCB Octet Rule H HCH H ::: : : :N :C :: O N: O: Na + :Cl : - MgCl2 L3-4 Exceptions :F O B F: :: :: :: :F: F .. Xe F .. : F H. + : :: .H : :: H:H : Cl: Cl : :: :: © 2004 M.Kubinec, A. Pines © 2000 A.Pines M.Kubinec UCB : Cl . + . Cl : H Cl : HNH H .. F SF6 : ChemQuiz ChemQuiz© 13.1 Which is the correct Lewis electron dot structure of formaldehyde? : : :: L3-6 L13-1 L3-7 © 2000 A.Pines M.Kubinec UCB : : H © 2004 M.Kubinec, A. Pines L13-2 : A) C::O ::O B) C:::O: :::O : H C) H:C:O:H Ionic: More electronegative element captures e- Summary +Li :F: Chemical Bonding : :: Resonance, Bond Order Electronegativity :: :: +O H H CH2O Ozone Covalent: Electrons shared equally :Cl: Cl : + Dipole, symmetry Dipole, No Dipole Dipole O O+ - O- -O O O C O -2 O O C 1½ O 1½ 3 O 1½ : :: :: δ- Polar Covalent: Unequal sharing, Dipole moment δ+ Carbonate - O O C O O OC O - - O O- O H Cl: :: :: Benzene L4-4 © 2000 A.Pines M.Kubinec UCB L3-11 © 2001 UC Regents Formal Charge (‘covalent’ electron distribution) (‘covalent’ Oxidation Number :: :: Lewis Dot Structure: :: Lewis Dot Structure: Share electrons equally:. N . (5) Compare to atoms: O: N :O: O: (7) Divide up electrons: (More electronegative captures e-) N (2) :: O: N :O: - (‘Ionic’ electron distribution) (‘Ionic’ - :: :O: (8) : :: O: (6) :: :: .N . (5) 0 O: (6) Compare to atoms: .N . (5) +3 :: :: Formal Charge: © 2001 UC Regents © 2004 M.Kubinec, A. Pines -1 L4-11 Oxidation number: © 2001 UC Regents -2 L13-4 L4-10 © 2004 M.Kubinec, A. Pines 1 L 13: "Covalent Bonding, Resonance, Formal Charge 2/17/2010 Chemical Bonding Ionic: More electronegative element captures e- +Li :F: Covalent: Polar: Unequal sharing, Dipole moment Electrons shared equally :Cl: Cl : :: :: Electronegativity :: :: :: δ- + Dipole, Dipole, symmetry No Dipole Dipole δ+ H Cl: :: :: © 2004 M.Kubinec, A. Pines L13-5 ChemQuiz© 13.2 + - Which of the following molecules is does not have a dipole moment? A) C O B) O=C=O O C) H C H © 2004 M.Kubinec, A. Pines L13-6 Resonance, Bond Order Ozone O - O O C O O O C - O O O C O O O C 1½ O 2- 1½ 3 Carbonate - O O O O -- O O - O O 1½ Benzene © 2004 M.Kubinec, A. Pines L13-8 © 2004 M.Kubinec, A. Pines 2 L 13: "Covalent Bonding, Resonance, Formal Charge 2/17/2010 ChemQuiz© 13.3 How does the NO bond order change in the process: process: nitrite O N O O N O2 - nitrate N O3 - O O N A) Increase © 2004 M.Kubinec, A. Pines B) Same C) Decreases L13-9 Formal Charge (‘covalent’ electron distribution) :: Lewis Lewis Dot Structure: Share electrons equally: .N . (5) Compare to atoms: :: O: N :O: - :: : O: (7) .N . (5) 0 :: :: O: (6) Formal Charge: © 2004 M.Kubinec, A. Pines -1 L13-11 Formal Charge (‘covalent’ electron distribution) Possible Possible Lewis Dot Structures for OCN-: [:O C N:]- [:O C N:]- [:O C N:]N:] N:] N:] FC: -1 • Minimize the formal charge on individual atoms • Negative charge on most electronegative atom • Small formal charges on individual atoms better than large ones L13-12 © 2004 M.Kubinec, A. Pines © 2004 M.Kubinec, A. Pines :: : : : 0 : : -1 : :: 0 0 0 +1 0 -2 3 L 13: "Covalent Bonding, Resonance, Formal Charge 2/17/2010 ChemQuiz© 13.4 How does the Formal Charge of nitrogen change for the process: N O2 - O N - O - N O3 - O O N O A) Increase © 2004 M.Kubinec, A. Pines B) Same C) Decreases L13-13 Oxidation Number (‘Ionic’ electron distribution) :: Lewis Lewis Dot Structure: Divide up electrons: (More electronegative electronegative captures e-) :: O: N :O: - :: : N (2) :O: (8) :: :: Compare to atoms: .N . (5) +3 O: (6) Oxidation number: © 2004 M.Kubinec, A. Pines -2 L13-15 Lecture Complete © 2004 M.Kubinec, A. Pines L13-18 © 2004 M.Kubinec, A. Pines 4 ...
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This note was uploaded on 06/29/2010 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at University of California, Berkeley.

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