Unit 12: Chemical Bonding

Unit 12: Chemical Bonding

(Chapter 15)

I.  Definitions

A.  Chemical Bonds

B.  Types of Chemical Bonds

1.  Ionic

2.  Covalent Bonds

3.  Metallic Bonds

C.  Octet rule (Rule of 8)

II. Examples of Bonding Types

A.  Ionic Bonding:

B.  Covalent Bonding

C.  Metallic Bonding

III.  Ionic Compounds and Lewis Dot Diagrams

A.  Review of Lewis Dot Structures

1.  Ex. Li, Be, B, C, N, O, F, Ne

B.  How Ionic Compounds are Formed

1.  Ex. NaCl

Na: 1s2 2s2 2p6 3s1

Cl: 1s2 2s2 2p6 3s2 3p5

C.  Writing Lewis Dots Structures for Ions

1.  Ex. Li+, Be+2, B+3, C+4, N-3, O-2, F-1

D.  Lewis Dot Diagrams of Ionic Compounds

1.  Ex.1 NaCl

2.  Ex.2 MgF2

IV.  Covalent Compounds and Lewis Dot Diagrams

A.  Lewis structures, Bonding pairs, Symbols

B.  Types of Covalent Bonds

1.  Single

a)  ______are shared in a bond (___ from each atom)

2.  Double

a)  ______of e- are shared (_____ total)

3.  Triple

a)  ______of e- are shared (_____ total)

C.  Rules for Drawing Lewis Dot Diagrams

1.  Count valence electrons for entire species

2.  Use one pair of electrons to form a bond between each pair of bound atoms

3.  Count the number of electrons remaining and distribute according to octet rule (or the “duet” rule for hydrogen)

4.  Lack of electrons requires multiple bonds

D.  But Remember....

1.  The Structure MUST Have: the right number of atoms for each element, the right number of electrons, the right overall charge, and 8 electrons around each atom (ideally).

E.  Examples

1.  F2 NH3

2.  H2O NH4+

3.  O2 N2

**Note** There are exceptions !! (For extra help, see worksheets in packet)

V.  VSEPR: Shapes of Molecules

A.  VSEPR-Definition

B.  Using the VSEPR Model

1.  Electron Pair

a)  Any valence e- around an atom that repel other e-

(1)  Single unpaired e-

(2)  Lone pair e-

(3)  Bonding pairs (single, double, triple bonds = 1 e- group)

C.  Basic Shapes and Bond Angles

VI.  Polar Bonds and Polar Molecules

A.  Polar Bond-definition

1.  Ex. HCl

B.  Predicting Bond Polarity

C.  Polar Bonds and Polar Molecules

1.  Types of Bonds: e/n differences

a)  Nonpolar Covalent

(1)  e- are ______

(2)  Difference between ______and _____

(3)  Ex. CS2

b)  Polar Covalent

(1)  e- are ______

(2) 

(3)  Difference between _____ and _____

(4)  Ex. CF4

c)  Ionic

(1)  e- are ______

(2)  Difference in e/n between _____ and ______

(3)  Ex. NaCl

D.  Polar Molecules (dipole)

1.  Definition

2.  Drawing Polar Molecules

a)  Ex. CH3Cl

3.  Rules for determining if a molecule is polar

a)  Shape is crucial (determine the shape 1st)

(1)  All non-polar bonds = nonpolar molecule

(2)  Polar bonds à see if they cancel each other out

(a)  If they all cancel = ______

(b)  If they are unbalanced = ______

VII.  Special Types of Bonding

A.  Hydrogen Bonding

1.  Definition and Examples

a)  Force in which a hydrogen atom covalently bonded to a nonmetal is simultaneously attracted to a neighboring nonmetal atom

2.  Elements that undergo H-bonding

3.  Effects on Physical Properties

B.  Van der Waals (Dispersion) Forces

1.  ______force between the molecules of a substance

2.  Force of attraction between an instantaneous and induced dipole”

VIII. Solids

A.  Classes of Solids

1.  Molecular

2.  Ionic

3.  Network Covalent

4.  Metallic

B.  Comparison of Solids