CHEM 261 1st Edition Lecture 5Outline of Last Lecture:I. Polar Covalent Bonds and Electronegativity RecapII. Dipole Moment RecapIII. Formal ChargeIV. ResonanceV. Brønsted-Lowry Acids and BasesOutline of Current Lecture:I. Recap of everything thus farRecap:-Electrons are not static…orbitals! FILLED orbitals are HAPPY orbitals-Energy level diagrams:-Lewis Dot Structures:-How does this bonding occur? (Valence Bond Theory) The electrons in the overlap of the hybridorbitals s and p-Sp3 = 4 bonds (single bonds) , sp2 = 3 bonds (double bonds), sp= 2 bonds (triple bonds)-Bond trends: As bond strength increases, bond length decreases!-Formal Charge is an accounting mechanism! -Formula for formal charge: (# valence electrons) - (# of bonds) - (# nonbonding electrons)-The stabilization of an atom = delocalization of an electron = resonance! ** Molecular structures can be drawn in a variety of ways to account for delocalization of the electronAcids and Bases: H+ = protonH-A + B A- + HB(-log(Ka))= pKa (low pKa = strong acid)-Large Ka value = strong acid-Weak acid corresponds with strong base, and vice
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