Chem 261 1st Edition Lecture 6 Outline of Last Lecture:I. Snow day- no lecture material covered today. Outline of Current Lecture:I. Using pKa to determine equilibriaII. Lewis Acids and BasesIII. Non-covalent InteractionsIV. AlkanesV. Functional GroupsVI. Alkyl GroupsUsing pKa to determine equilibria:[ ] [ ] = equal concentrations** in this example, acetic acid is more willing to give up its hydrogen (has a low pKa value!)** protons will move from a lower to a higher pKa Lewis Acids and Bases:Lewis acid- electron ACCEPTORLewis base- electron DONORLewis acids: no scale!Non-covalent Interactions:-Nonbonding interactions between molecules. They involved attractions and repulsions1. Hydrogen bonds (strongest)A hydrogen bond is the attractive force between the hydrogen (partial positive charge) attached to an electronegative atom (partial negative charge) of one molecule and the electronegative atom of another nearby molecule. The best example of hydrogen bonding is WATER!2. Dipole-Dipole InteractionsDipole-dipole interactions occur between the positive end of one polar molecule and the negative end of another, different polar molecule. 3. Van der Waals Forces/Dispersion forces (weakest)Electron distribution can change, and these temporary changes causes for brief attractions and repulsions between moleculesAlkanes:-Molecular formulae are CxHx….only for NON-RING structures-all alkanes are sp3 bonded compounds made up of carbon and hydrogen (hydrocarbons!)-all sigma bonded/single bondsWhy are alkanes important?-petroleum =mostly alkanes-simple structures and relatively unreactive…good introduction to organic chemistry before more complex structures**Alkane names correspond to the # of carbons** Linear chains = one single chain alkaneFunctional Groups:Things to know…A functional group is a group of atoms within a molecule that has a characteristic chemical behavior. An “alkyl” group is any alkane as a functional group“R” = rest of molecule (not the functional group)R’, R” are NOT RNaming: Replace “ane” with “yl”Functional Groups to
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