OchemTest1

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victimsofadown
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170765
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OchemTest1
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2012-09-14 03:46:20
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OchemTest1
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  1. Bonding types w/ electronegativity ranges
    • Nonpolar Covalent: 0-<.5
    • Polar Covalent: .5-1.7
    • Ionic: >1.7
  2. Valence Bond Theory vs. Molecular Orbit Theory
    • VBT: Valence bond theory treats every bond as the sharing of electron density between two atoms as a result of the constructive interference of their atomic orbitals
    • MOT: uses a mathematical method called the linear combination of atomic orbitals (LCAO) to form molecular orbitals. Each molecular orbital is associated with the entire molecule, rather than just two atoms.
    • #atomic orbitals results in # molecular orbitals (antibonding > nonbonding > bonding)
  3. Geometries organized by hybridized orbitals with angle
    • sp3: tetrahedral (109.5), trigonal pyramidal, bent
    • sp2: trigonal planar (120), bent
    • sp: linear (180)
  4. Types of intermolecular forces
    • Dipole-dipole
    • H-Bonding
    • London dispersion
  5. Formal charge on C atoms w/ relation to bonds
    Carbon atoms with formal charges will only hold 3 bonds
  6. 3D Structures
    • Wedge: coming out of page
    • Dash: going into page
  7. Resonance Structure rules
    • 1. Don't ever break single bonds
    • 2. Never exceed an octet for 2nd row elements
  8. Resonance Structure Pattern Recognition
    • 1) Allylic lone pair: lone pair next to double bond.  Lone pair creates new double bond, old double bond moves to lone pair at end.
    • 2) Allylic cation: Cation next to double bond. Double bond moves to positive formal charge, new positive formal charge where double bond is missing.
    • 3) Lone Pair Next to cation: Lone pair creates double bond, new positive formal charge formed.
    • 4) Double bond between 2 atoms of differing electronegitivity: Double bond moves toward more electronegative atom, creating a negative formal charge, positive formal charge left on other atom.
    • 5) Conjugated double bonds in a ring: Each bond moves over.
  9. Ranking of resonance structures
    • 1) Minimize the charge (>2 charges is not significant) *Nitro groups chargest aren't associated with that limit
    • 2) Electronegative atoms can bear a positive charge ONLY if they have an octet (most significant resonance structures have an octet on all atoms)
    • 3) 2 carbon atoms should not have opposite charges
  10. Define bronsted-lowry
    • acid: proton donator
    • base: proton acceptor
    • Always takes 2 lines
    • line 1: from electron on base to H on acid
    • line 2: from bond between H on acid and its connected atom
  11. pKa value range
    • -10 (very strong acid)
    • 50 (very week acid)
  12. Qualitiative acid strength approach
    • Look at conjugate base to determine stability
    • 1) Which ATOM is the charge on? (more electroneg OR larger)
    • 2) Which has more resonance?
    • 3) Induction (pulling of e to sigma bond by electroneg atom)
    • 4) Orbitals (smaller/rounder = stronger acid)
    • EXCEPTION: H-C=C-H + NH2- <-> H-C=-C:- + NH3
    • Acetylene is stronger acid!
  13. How does the equilibrium go in an acid/base?
    It favors the weaker acid / more stable conj base
  14. How can solvent affect pKa?
    Large/bulky bases have less interaction with solute, and are less stable (weaker acid) 
  15. Lewis
    • Acid: electron acceptor
    • Base: electron donator

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