What you should remember from the last lecture

What you should remember from the last lecture The syllabus is at h"p://www.chem.uky.edu/courses/che230/ Lewis Dot Structures and Formal Charges. Be able to construct these for any main group atoms/molecules, for single and mul:ple bonds. Isomers. Same molecular formulae, different structures. Be able to construct many. esonance different ways to distribute electrons within a structure. The hybrid is the only thing that is real.

What you should remember from the last lecture 1. Electron configura:ons for the elements 2. The ctet ule 3. Lewis Dot Structures 4. Calcula:on of Formal Charges (and the actual distribu:on of charges due to electronega:vi:es) C C 8 electrons on oxygen 6 electrons on carbon

Today ybridiza:on Sigma and π bonding, bond lengths and strengths For Prac:ce: Construct the Lewis Dot Structure, assign formal charges, and predict bond polari:es for the following: C Carbon monoxide C C Methyl isocyanide

Alkynes you may know.. Ethinylestradiol C 3 S S S C 3 I S C 3 C 3 C 3 C 3 Calicheamicin

What you should remember from the last lecture ybridizafon The mixing of atomic orbitals to form hybrid orbitals. The # orbitals in = # orbitals out. sp 3, sp 2, and sp hybridizafons know what they look like, the number of hybrid orbitals and the number of p orbitals. Geometry: sp 3 orbitals are 109.5 apart (tetra- hedral), sp 2 orbitals are 120 apart (trigonal), and sp orbitals are 180 apart (linear). esonance. Different alloca:ons of electrons within Lewis structure. Individual resonance forms do not exist. The hybrid is the only thing that is real.

Which Lewis Dot Structure is ight? C C C 5 electrons around C 7 electrons around C C C 6 electrons around C 8 electrons around δ C δ C C 8 electrons around C 8 electrons around The hybrid Dipole moment is 0.12 D (very small).

Which Lewis Dot Structure is ight? C C C C 7 electrons around 5 electrons around C C C C C 8 electrons around 6 electrons around C δ C δ C The hybrid C C C C 8 electrons around 8 electrons around C

A Lifle ybridiza:on Prac:ce 2 sp 2 (one π bond, therefore one p orbital) 1 sp 3 (no π bonds, therefore no p orbitals) 4 3 sp 2 (one π bond, therefore one p orbital) sp (two π bonds, therefore two p orbitals) Azidothymidine (Zidovudine, AZT)

A Lifle ybridiza:on Prac:ce C 3 S C 3 C 2 sp 2 (one π bond, therefore one p orbital) Penicillin G

What you should remember from the last lecture sp 3, sp 2, and sp hybridizafons Be able to iden:fy the hybridiza:on of carbon and of heteroatoms (oxygen, nitrogen, etc). Be able to determine what orbitals contains non- bonding pairs of electrons on and. Acid- Base Chemistry. emember the defini:ons of Lewis and Bronsted acids, K a and pk a and how to use these numbers to predict K eq for acid- base reac:ons.

Make a predic:on! Longer (~1.54 Å) formed by overlap of two sp 3 orbitals 1 S Glutathione (a supremely important anfoxidant) 2 Methamphetamine 2 Shorter (~1.5 Å) formed by overlap of an sp 3 orbital with an sp 2 orbital 3 4 EssenFally idenfcal! (~ 1.4 Å)

Drugs du Jour C 3 C 3 Ephedrin C 3 Adrenaline C 3 C 3 Pseudoephedrin C 3 C 3 C 3 Methamphetamine C 3 Methenedioxy methamphetamine (MDMA, ecstasy)

What you should remember from the last lecture sp 3, sp 2, and sp hybridizafons Be able to iden:fy the hybridiza:on of carbon and of heteroatoms (oxygen, nitrogen, etc). Be able to determine what orbitals contains non- bonding pairs of electrons on and. Acid- Base Chemistry. emember the defini:ons of Lewis and Bronsted acids, K a and pk a and how to use these numbers to predict K eq for acid- base reac:ons.

What you should remember from the Acid- Base Chemistry. emember the defini:ons of Lewis and Bronsted acids, K a and pk a and how to use these numbers to predict K eq for acid- base reac:ons. emember some pka s: S- 10-16 - 35 C 2-45- 50 C C 24 last lecture C 2 42 C 2 20 4.7

3 P 4 + 2 2 P 4 + 3 ne note on acid- base equilibria pk a 2.2 pk a -1.7 2 P 2 P

What you should remember from the Acid- Base Chemistry. emember the defini:ons of Lewis and Bronsted acids, K a and pk a and how to use these numbers to predict K eq for acid- base reac:ons. emember some pka s: S- 10-16 - 35 C 2-45- 50 C C 24 last lecture C 2 42 C 2 20 4.7

What you should remember from the last lecture FuncFonal Groups. A commonly occurring group of atoms with characterisfc chemistry and properfes. Drawing. Be aware of condensed drawing conven:ons: C 3 C 2 C 2 C 3 and Alkanes: ydrocarbons with no mul:ple bonds. Alkenes: ydrocarbons with one or more C- C double bonds. Alkynes: ydrocarbons with one or more C- C triple bonds. AromaFc ydrocarbons: ydrocarbons related to benzene and other cyclic polyenes.

Some aroma:cs of interest Benzo[a]pyrene Benzo[a]pyrene- 7,8- dihydrodiol- 9,10- epoxide

Exam 1 in class next Wednesday 1. Get a good night s sleep beforehand. 2. Eat a decent breakfast. 3. Bring photo ID. 4. The exam will cover everything we have covered in class through next Monday. Before you begin this exam: First: You are allowed to have a simple model set at your seat. Please put away all other materials. Calculators will not be needed. Second: Place your student iden:fica:on on your desk. A proctor will come around to check everyone s ID. Third: ead through the en:re exam. Your goal is to score as many points as possible. Do not waste :me on problems that you can t do if there are others that look easy. Fourth: EAD EAC QUESTI CAEFULLY. Be sure you answer the ques:on that is asked. Fih: This exam must be turned in by 8:50 AM SAP. There will be no extensions, so budget your :me carefully.

A bit of prac:ce.. Which is the shortest bond: of this pair: 1 1.11 Å 1.09 Å 2 C 2 Which is the strongest bond: of this pair: 1 98 kcal/mol 125 kcal/mole C 2 2 Which is the most acidic bond: of this pair: 1 pka 45 C 2 pka 24 2

What you should remember from the last lecture FuncFonal Groups. A commonly occurring group of atoms with characterisfc chemistry and properfes. Drawing. Be aware of condensed drawing conven:ons: C 3 C 2 C 2 C 3 and Alkanes: ydrocarbons with no mul:ple bonds. Alkenes: ydrocarbons with one or more C- C double bonds. Alkynes: ydrocarbons with one or more C- C triple bonds. AromaFc ydrocarbons: ydrocarbons related to benzene and other cyclic polyenes.

What you should remember from the last lecture FuncFonal Groups. A commonly occurring group of atoms with characterisfc chemistry and properfes. Alcohols, amines, and thiols. These related func:onal groups (-, - S, - 2 ) have func:onal groups with lone pairs of electrons. These are nucleophiles: tend to react with electron- deficient sites in other molecules. Alkyl halides: Compounds with a C- X bond (X=halogen). The electronega:vity of halides makes the carbon somewhat electron- deficient. These are electrophiles.

A bit of prac:ce.. Which acid- base reac:on is favorable (i.e. Keq >1)? C 3 Li + C 4 + Li S- 10-16 - 35 C 2-45- 50 pka = 16 pka = 45 C C 24 C 2 42 What are the formal charges on and P? 4.7 20 C 2 C 3 P C 3 C 3 C 3 P C 3 C 3 P

What you should remember from the last lecture Carbonyl- based Func:onal Groups: Aldehyde Ester Ketone 2 Amide Carboxylic Acid Cl Acid Chloride C itrile

ydrogen bonding in pep:des

A bit of prac:ce.. Which acid- base reac:on is favorable (i.e. Keq >1)? C 3 Li + C 4 + Li S- 10-16 - 35 C 2-45- 50 pka = 16 pka = 45 C C 24 C 2 42 What are the formal charges on and P? 4.7 20 C 2 C 3 P C 3 C 3 C 3 P C 3 C 3 P