Double and Triple Bonds or or or H H ethylene formaldehyde formaldimine Copyright 2010 Pearson Prentice Hall,Inc. Chapter 1 11
Chapter 1 11 Double and Triple Bonds
Bonding Patterns Valence Bonds Lone Pair electrons Electrons c 4 4 0 N 5 3 1 6 2 2 Halides 7 1 3 (F,CI,Br,I) Chapter 1 12
Chapter 1 12 Bonding Patterns Valence electrons # Bonds # Lone Pair Electrons C N O Halides (F, Cl, Br, I) 4 4 0 5 3 1 6 2 2 7 1 3
Lone Pairs H lone pair HH lone pairs H H-C-N-H H H一C一 lone pairs HH HHH H methylamine ethanol chloromethane Copyright 2010 Pearson Prentice Hall.Inc. Chapter 1 13
Chapter 1 13 Lone Pairs
Dipole Moment C一CI H H chloromethane chloromethane Pearson Prentice Hall.Inc Amount of electrical charge x bond length. Charge separation shown by electrostatic potential map (EPM). Red indicates a partially negative region and blue indicates a partially positive region. Chapter 1 14
Chapter 1 14 Dipole Moment • Amount of electrical charge x bond length. • Charge separation shown by electrostatic potential map (EPM). • Red indicates a partially negative region and blue indicates a partially positive region
Electronegativity and Bond Polarity 。 Electronegativities can be used to predict whether a bond will be polar. 。 Since the electronegativity of carbon and hydrogen are similar,C-H bonds are considered to be nonpolar. H 2.2 Li Be 0 1.0 1.6 2.0 2.5 3.0 3.4 4.0 Na Mg Si P CI 0.9 1.31.61.9 2.22.6 3.2 K Br 0.8 3.0 2.7 Chapter 1 15
Chapter 1 15 Electronegativity and Bond Polarity • Electronegativities can be used to predict whether a bond will be polar. • Since the electronegativity of carbon and hydrogen are similar, C—H bonds are considered to be nonpolar