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Chapter 1
Important 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
O
O
O
H
NH
OH
H
HO
O
Tylenol
Aspirin
Friedrich Wöhler in 1828
Organic compound
Inorganic compound
H
H
O
heat
+N
H
O C N
H
Ammonium cyanate
H2N
NH2
Uria (constituent of urine)
C H
H
Methane
Introduction to Organic Chemistry
O
O
O
H
NH
OH
O
Aspirin
H
HO
Tylenol
C H
H
Methane
• What is the shape of these molecules? < Structure >
• What these molecules do/how they do? < Function/Mechanism >
• How they can be obtained?
< Synthesis >
Introduction to Organic Chemistry
H
N
O
R
N
H
H
H
N
O
R
H
N
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
Wave Functions: Solutions to Schrödinger's Equation (contains
the information of electron’s energy and position (H
An orbital is a region of space where the probability of
finding an electron is large.
Molecular Orbitals
Atomic orbitals (AOs) combine to become molecular orbitals (MOs):
the number of molecular orbitals that results always equals the number of
atomic orbitals that combine.
SP3–Hybrid Atomic Orbital
Hybridization: A mathematical process combining individual wave functions
The shape of an sp3 orbital
The Structure of Methane
σ (sigma) bond
The Structure of Ethane
SP2–Hybrid Atomic Orbitals
π (pi) bond
An sp2-hybridized carbon
SP–Hybrid Atomic Orbitals
An sp-hybridized carbon
Bond Lengths and Angles of
Ethyne, Ethene, and Ethane
sp-hybridized C
sp2-hybridized C
sp3-hybridized C
s-character
50%
33.3%
25%
p-character
50%
66.6%
75%
***The higher s-character of a carbon atom, the higher its electronegativity.
Rule of thumb in using hybridized
atomic orbitals for actual molecules
SP3 hybridization: Any atom in a molecule that is not a part of a double
or triple bond – Tetrahedral
109.5°
109.5°
H
109.5°
O H
H
N H
H
H
C H
H
H
109.5°
SP2 hybridization: Any atom in a molecule that is a part of a double bond
– Trigonal planar
H
H
H
N C
C C
H
H
H
H
H
H B
O C
H
H
H
H
H C+
H
SP hybridization: Any atom in a molecule that is a part of a triple bond
– Linear
N N
N C CH3
Rule of thumb in using hybridized
atomic orbitals for actual molecules
What is the hybridization of the indicated atom(s) in each molecule?
CH3
C C
(a)
Me
(b)
Me
C
(c)
+
Me
O
O
(d)
(e)
(f)
O
(h)
(g)
(i)
N
O
(j)
Me
Me
Al
Me
(k)
O
H
(l)
N
Predicting Molecular Geometry:
VSEPR and Molecular Orbital Theory
The electron configurations of some second-row elements.
Chapter 1
Suggested 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