University Of PennsylvaniaCollege of General StudiesProfessor William A. Price, Ph.D.

CHEM 241-601Organic Chemistry, 9th EditionBy T.W. Graham Solomons

From the Bark of the Pacific Yew Tree

Introduction: Structure and BondingAtomic structureLewis StructuresResonanceStructural FormulasAcids and Bases

Nucleus is a Tiny Fraction of the Volume of an Atom

Orbitals are Probabilities

2s Orbital Has a Node

The p Orbital

px, py, pz

Electron Configurations

Lewis Dot Structure of Methane

Tetrahderal Geometry

Bonding Characteristics of Period 2 Elements

Saturated with Hydrogen

All Have the Same GeometryAll Have 4 Regions of Electron Density

A Saturated Hydrocarbon

Nitromethane

Nitromethane has 2 Formal Charges

Both Resonance Structures Contribute to the Actual Structure

Resonance RulesCannot break single (sigma) bondsOnly electrons move, not atoms3 possibilities:Lone pair of e- to adjacent bond positionForms p bond- p bond to adjacent atom- p bond to adjacent bond position

Curved Arrow Formalism Shows flow of electrons

Resonance Stabilization of IonsPos. 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 [CH2NH2]+

Propose Lewis StructuresH2CO2b) O3 c) N2O

d) NH3Oe) C2H3ClO f) C2H5NO

ProblemDraw [NO2]+ and [NO2]-. 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