Chapter 1Important Concepts and Principles

Ch1.3: Valence, C–C Bonds (single, double, triple), Isomer(constitutional), Molecular/Structural formula, Connectivity

Ch1.4-8: Ionic/covalent bonds, Octet rule, Ions, Electronegativity Lewis structure, Formal charges,Resonance structures, Resonance stabilization

Ch1.9-15: Atomic/molecular orbitals Orbital hybridization (sp3, sp2, sp)Sigma(σ)/Pi (π)bonds (structure of ethane/ethene/ethyne)Stereoisomer

Ch1.16: Molecular geometry (tetrahedral, trigonal planar,linear, trigonal pyramid, bent)

Ch1.17: Representation of structural formulas (dash, condensed,bond line, three-dimensional)

Introduction to Organic Chemistry

NH

O

HO

Tylenol

CH

H HH

Methane

O

O

OH

O

Aspirin

NH

H HH

Ammonium cyanate

+ NCOheat O

NH2H2N

Uria (constituent of urine)

Inorganic compound Organic compound

Friedrich Wöhler in 1828

Introduction to Organic Chemistry

NH

O

HO

Tylenol

CH

H HH

Methane

• What is the shape of these molecules?• What these molecules do/how they do?• How they can be obtained?

< Structure >< Function/Mechanism >< Synthesis >

O

O

OH

O

Aspirin

Introduction to Organic Chemistry

O

NH

N

RH

H

O

NH

N

RH

H

+

Electronegativity

A measure of the ability of an atom to attract electrons

Formal Charges

Indicator of how many electrons are gained/lost by an atom

Formal Charges

Practice: Find formal charges for the red atoms.

Atomic Orbitals

An orbital is a region of space where the probability offinding an electron is large.

Wave Functions: Solutions to Schrödinger's Equation (containsthe information of electron’s energy and position (H

Atomic orbitals (AOs) combine to become molecular orbitals (MOs):the number of molecular orbitals that results always equals the number ofatomic orbitals that combine.

Molecular Orbitals

Hybridization: A mathematical process combining individual wave functions

SP3–Hybrid Atomic Orbital

The shape of an sp3 orbital

The Structure of Methane

σ (sigma) bond

The Structure of Ethane

SP2–Hybrid Atomic Orbitals

An sp2-hybridized carbon

π (pi) bond

SP–Hybrid Atomic Orbitals

An sp-hybridized carbon

Bond Lengths and Angles ofEthyne, Ethene, and Ethane

s-character 50% 33.3% 25%

p-character 50% 66.6% 75%

***The higher s-character of a carbon atom, the higher its electronegativity.

sp2-hybridized Csp-hybridized C sp3-hybridized C

Rule of thumb in using hybridizedatomic orbitals for actual molecules

SP3 hybridization: Any atom in a molecule that is not a part of a doubleor triple bond – Tetrahedral

SP2 hybridization: Any atom in a molecule that is a part of a double bond– Trigonal planar

SP hybridization: Any atom in a molecule that is a part of a triple bond – Linear

N N N C CH3

C CH

H

H

HN C

H

H

HO C

H

H

109.5°

109.5°

109.5°

109.5°

H BH

HH C+

H

H

CH

HH

H NH

HH O

HH

Rule of thumb in using hybridizedatomic orbitals for actual molecules

What is the hybridization of the indicated atom(s) in each molecule?

(a) (b)CCH3

CMe

CMe

Me+

(c)

(d)(e)

O

OO (f)

(g) N(h) (i)

MeAl

Me

Me

(j) N(l)

O

O(k)

H

Predicting Molecular Geometry:VSEPR and Molecular Orbital Theory

The electron configurations of some second-row elements.

Chapter 1Suggested Problems

Ch1.3: Valence, C–C Bonds (single, double, triple), Isomer(constitutional), Molecular/Structural formula, Connectivity:Problems 1,33, 1.36

Ch1.4-8: Lewis structure, Formal charges:Problem 1.1, 1.2, 1.3, 1.18, 1.19

Resonance structures, Resonance stabilization:Problem 1.4, 1.5, 1.6, 1.27, 1.31, 1.32

Ch1.9-15: Sigma(σ)/Pi (π)bonds (structure of ethane/ethene/ethyne)Stereoisomer: Problem 1.8, 1.34

Ch1.16: Molecular geometry (tetrahedral, trigonal planar,linear, trigonal pyramid, bent): Problem 1.10, 1.11, 1.28–30

Ch1.17: Representation of structural formulas (dash, condensed,bond line, three-dimensional): Problem 1.13, 1.16, 1.22, 1.23