chem104alecture19 - Chem 104A, UC, Berkeley Chem 104A, UC,...

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1 Chem 104A, UC, Berkeley LUMO receives electrons lowest energy orbital available characteristic for electrophilic component electrons from the HOMO are donated most available for bonding most weakly held electrons characteristic for nucleophilic component Chem 104A, UC, Berkeley π Molecular Orbitals of Ethene Chem 104A, UC, Berkeley Chem 104A, UC, Berkeley Molecular Orbital Analysis of Ethene Dimerisation the reaction is said to be a " symmetry forbidden " – interestingly, this reaction is rare and very slow !
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2 Chem 104A, UC, Berkeley π Molecular Orbitals of 1,3-Butadiene Chem 104A, UC, Berkeley Chem 104A, UC, Berkeley Molecular Orbital Analysis of Diels-Alder reaction Chem 104A, UC, Berkeley Acid-Base Chemistry Reading : MT 6
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3 Chem 104A, UC, Berkeley In 1923, within several months of each other, Johannes Nicolaus Brønsted (Denmark) and Thomas Martin Lowry (England) published essentially the same theory about how acids and bases behave. The Acid Base Theory of Brønsted Brønsted and Lowry An acid is a "proton donor." A base is a "proton acceptor." Chem 104A, UC, Berkeley HCl + H 2 O <===> H 3 O + + Cl¯ HCl - this is an acid, because it has a proton available to be transfered. H 2 O - this is a base, since it gets the proton that the acid lost. Now, here comes an interesting idea: H 3 O + - this is an acid, because it can give a proton. Cl¯ - this is a base, since it has the capacity to receive a proton. Notice that each pair (HCl and Cl¯ as well as H 2 O and H 3 O + differ by one proton (symbol = H + ). These pairs are called conjugate pairs conjugate pairs . Chem 104A, UC, Berkeley weaker conjugate base Weaker conjugate acid stronger base stronger acid NaCl + H 2 O ---> NaOH + HCl weaker conjugate base weaker conjugate acid stronger base stronger acid NH 3 + H 2 O ---> NaOH + NH 4 Cl Chem 104A, UC, Berkeley + + + O H A H O H A H n n 3 1 2 ] [ ] ][ [ log 3 1 1 A H O H A H pK n n a + = weak pK strong pK a a > < 0 0
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4 Chem 104A, UC, Berkeley + + + O H A H O H A H n n 3 1 2 + + + OH NH O H NH 4 2 3 Amphoteric Compound Chem 104A, UC, Berkeley Oxyacids AO p (OH) q p=# of nonhydrogenated oxygen atom A=Si, N, P, As, S, Se, Te, Cl, Br, I A ----O H δ +
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This note was uploaded on 04/12/2008 for the course CHEM 104 taught by Professor Yang during the Spring '04 term at University of California, Berkeley.

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chem104alecture19 - Chem 104A, UC, Berkeley Chem 104A, UC,...

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