Chapter 6: Chemical Bonding
Covalent Focus

6.1 Intro to Bonding

6.2 Lewis Structures

6.3 Covalent Formulas
6.1 Intro to Bonding

Learning Targets
◦ Describe and explain chemical bonding.
◦ Describe ionic and covalent bonding.
6.1 Intro to Bonding

Chemical Bond:
 Force of attraction between two atoms
 Due to mutual attraction of nuclei for electrons
6.1 Intro to Bonding

Why do atoms form bonds?
 Bonds allow atoms to become more stable by
achieving lower energy
 Forming a bond releases energy
 Breaking a bond absorbs energy
 Atoms gain or lose electrons to achieve noble gas
configuration (full shell)
6.1 Intro to Bonding

Octet Rule:
◦ Atoms tend to gain, lose, or share electrons
to get 8 valence electrons in order to achieve
a noble gas configuration
◦
◦
◦
◦
Li
O
Ne
C
6.1 Intro to Bonding

Electronegativity
 Measures how strongly an atom pulls electrons towards it
6.1 Intro to Bonding

What type of bond?
 Metals-metals: Metallic
 Metal-nonmetal: Ionic
 Nonmetal-nonmetal: Covalent
 Polar if atoms are different from each other
6.1 Intro to Bonding

Classify each of the following bonds:
◦ 1. H –C
◦ 2. N—N
◦ 3. Cu—Zn
◦ 4. Cs—F
◦ 5. C—F
6.1 Intro to Bonding

Ionic Bond
 Bond formed by attraction between cation
and anion
 One atom loses e-, one gains e-
6.1 Intro to Bonding
Properties of Ionic Compounds
 1. Crystalline

 Orderly arranged pattern of cations and
anions

2. Solid

3. High Melting/Boiling Points
6.1 Intro to Bonding

4. Hard and Brittle

5. White or Bright colors

6. Dissolve in Water

7. Conduct electricity
 Break apart into ions in water
6.1 Intro to Bonding

Covalent bond:
 Two atoms share electrons to gain an
octet

Polar covalent:
 Bond formed by two elements that have
different electronegativity
 Electrons spend more time with one atom
 Slight charges on atoms
 Dissolve in polar solvents (water, ethanol)
6.1 Intro to Bonding

Nonpolar covalent:
 Bond formed by two elements that have
the same or similar electronegativity
 Electrons spend equal time with each atom
 No charge on atoms
 Dissolve in nonpolar solvents (hexane)
6.1 Intro to Bonding
Properties of Covalent Compounds
 1. Crystalline or Amorphous
 2. All phases
 3. Soft
 4. Low melting/boiling point

6.1 Intro to Bonding

5. Dull Colors

6. Soluble based on polarity
 Polar dissolve; Nonpolar do not

7. Nonconductors
6.1 Intro to Bonding

Metallic Bond
 Positive nuclei (cations) exist separately in a sea of
electrons
6.1 Intro to Bonding

Properties of Metals
◦ 1. Conduct heat and electricity
◦ 2. Malleable
◦ 3. Ductility
◦ 4. Lustrous
6.2 Lewis Structures

Learning Targets:
 Draw Lewis dot structures for covalent molecules.
 Determine the polarity of a molecule.
 Use VSEPR to determine shapes of molecules.
6.2 Lewis Structures

Lewis Dot Structures
 Representation of molecules using nonbonding e-,
bonding e-, and atoms

Bonding Pair
 2 shared electrons

Lone Pair
 2 electrons not in a bond
6.2 Lewis Structures

1. Br2

2. N2

3. H2O

4. CH3I
6.2 Lewis Structures

5. HNO

6. C2H6

7. C2H4
6.2 Lewis Structures

Polarity
◦ Measure of uneven distribution of electrons
throughout a molecule
◦ 2 things to look for
 Asymmetry around central atom
 Different elements
 Lone pairs
6.2 Lewis Structures

Determine if polar or nonpolar
◦ 1. Br2
◦ 2. NH3
◦ 3. C2H6
◦ 4. CH3Cl
◦ 5. C2H4
◦ 6. H2O
6.2 Lewis Structures

Octet Exceptions
◦ B:
BH3
◦ I:
IF3
◦ Xe:
XeF4
6.2 Lewis Structures

Valence Shell Electron Pair Repulsion
(VSEPR) theory:
 Predicts shapes of covalent molecules using valence
electrons and bonds
 Electron pairs repel each other
 Look at central atom (with most atoms attached)
 Count atoms attached and lone pairs (only on central atom)
6.3 Covalent Formulas

Learning Targets:
 Write names and formulas of covalent compounds.
6.3 Covalent Formulas

Monoatomic
◦ Made of individual atoms

Diatomic
◦ Made of 2 atoms covalently bonded
 7 elements always found in pairs when pure element
 Diatomic 7:
 H2 , N2 , O2 , F2 , Cl2 , Br2 , I2
6.3 Covalent Formulas

Prefixes
Prefix
Number
Mono-
1
Di-
2
Tri-
3
Tetra-
4
Penta-
5
Hexa-
6
Hepta-
7
Octa-
8
Nona-
9
Deca-
10
6.3 Covalent Formulas

Writing a formula from a name:
◦ Only nonmetals
 1. In order of name, write symbols
 2. Prefixes determine subscript (# of atoms)
 No prefix on 1st element  1 atom
6.3 Covalent Formulas
You try!
 1. Dihydrogen monosulfide


2. Carbon tetrahydride

3. Iodine pentafluoride

4. Hydrogen monochloride

5. Triphosphorous pentoxide
6.3 Covalent Formulas

Naming a covalent compound
◦ Only nonmetals
 1. In order of formula, write name of each element.
 2. Add prefixes in front to show amount
 If only 1 of first element, ignore “mono”
 3. Change endings (all but first) to –”ide”
6.3 Covalent Formulas

You try!
1. CO2

2. SeO

3. IF7

4. PH3

5. N2O5
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