University Of Pennsylvania College of General Studies Professor William A. Price, Ph.D. CHEM Organic Chemistry, 9 th Edition By T.W. Graham Solomons

From the Bark of the Pacific Yew Tree

Introduction: Structure and Bonding Atomic structure Lewis Structures Resonance Structural Formulas Acids and Bases

Nucleus is a Tiny Fraction of the Volume of an Atom

Orbitals are Probabilities

2s Orbital Has a Node

The p Orbital

p x, p y, p z

Electron Configurations

Lewis Dot Structure of Methane

Tetrahderal Geometry

Bonding Characteristics of Period 2 Elements

“Saturated” with Hydrogen

All Have the Same Geometry All Have 4 Regions of Electron Density

A Saturated Hydrocarbon

Nitromethane

Nitromethane has 2 Formal Charges

Both Resonance Structures Contribute to the Actual Structure

Resonance Rules Cannot break single (sigma) bonds Only electrons move, not atoms 3 possibilities: –Lone pair of e - to adjacent bond position Forms  bond  bond to adjacent atom  bond to adjacent bond position

Curved Arrow Formalism Shows flow of electrons

Resonance Stabilization of Ions Pos. charge is “delocalized”

Bonding Pattens for C, N, and O

Common Cationic, Neutral and Anionic Forms

Two Nonequivalent Resonance Structures in Formaldehyde

Resonance in Acetate Anion

Resonance in [CH 2 NH 2 ] +

Propose Lewis Structures a)H 2 CO 2 b) O 3 c) N 2 O d) NH 3 Oe) C 2 H 3 ClO f) C 2 H 5 NO

Problem Draw [NO 2 ] + and [NO 2 ] -. Which ion has a “localized” charge and which has a “delocalized” charge. Explain.

Drawing Structures

Octane Representations

Condensed Formulas

Line-Angle Structures are Often Used as a Short-hand

Line-Angle Structures

Line-Angle structure Superimposed on Lewis Structure

Double Bonds are Shown

For Cyclic Structures, Draw the Corresponding Polygon

Some Steroids

Adrogenic/Anabolic Steroids

Anabolic Steroids

Benzene can be drawn as one of two resonance structures

Some Line-Angle Structures