Chapter 8- Covalent Bonding

How many sigma and pi bonds are in a single bond?

1 sigma no pi

How many sigma and pi bonds are in a double bond?

1 sigma, 1 pi

How many sigma and pi bonds are in a triple bond?

1 sigma, 2 pi

Endothermic Reaction

A greater amount of energy is required to break a bond in reactants than is released when the new bonds form in the products

Sigma Bond

A single covalent bond

dichlorine monoxide

Cl2O

Why do multiple bonds (double and triple) form?

Double and triple bonds form when four or more electrons are shared between two atoms. When this is shown in a Lewis structure, two or three lines are drawn connecting one atom to another, indicating that the two atoms are bonded together.

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: CO

Electrons: 10

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: HCN

Electrons: 10

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: H2CO

Electrons: 12

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: OCl2

Electrons: 20

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: SeCl2

Electrons: 20

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: BF3

Electrons: 24

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: CIF3

Electrons: 28

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: BF4-

Electrons: 32

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: CH4

Electrons: 8

Determine the total number of valence electrons, draw the Lewis Structures, and determine the shape for the following: H2S

Electrons: 8

Pi Bond

Formed when parallel orbitals overlap and share electrons

Molecule

Formed when two or more atoms bond

phosphoric acid

H3PO4

perchloric acid

HClO4

nitrous acid

HNO2

Name the 7 diatomic molecules. Note their physical state (solid, liquid or gas) at room temperature.

Hydrogen: Gas Nitrogen: Gas Oxygen: Gas Fluorine: Gas Iodine: Solid Chlorine: Gas Bromine: Liquid

iodine monochloride

ICl

iodine heptafluoride

IF7

Lewis Structure

In a Lewis structure, dots or lines are used to symbolize a single covalent bond

Exothermic Reaction

More energy is released than is required to break the bonds in the initial reactants

Give the number of valence electrons in N, C, As, Br, and Se. Predict the number of covalent bonds needed for each of these elements to satisfy the octet rule.

N- 5 valence electrons; 3 covalent bonds needed C- 4 valence electrons; 4 covalent bonds needed As- 5 valence electrons; 3 covalent bonds needed Br- 7 valence electrons; 1 covalent bond needed Se- 6 valence electrons; 2 covalent bonds needed

diphosphorus pentoxide

P2O5

Sulfur hexafluoride

SF6

SO3

Sulfite

Bond Dissociation Energy

The amount of energy required to break a bond

Why is PCl an exception to the octet rule, while PCl is not?

The central atom, P, expands its octet by involving higher energy orbitals to form PCl3. Therefore PCl3 is an exception to the octet rule while PCl3 is not

Covalent Bond

The chemical bond that results from sharing electrons

How does a covalent bond differ from an ionic bond?

The difference between a covalent bond and an ionic bond is that covalent bonds form when two atoms share electrons. In contrast, ionic bonds are forces that cause attractions between oppositely charged ions.

Which bond is shorter? Which is stronger?

The triple bond between carbon and nitrogen is shorter and stronger.

How do you determine the presence of sigma or pi bonds in a molecule?

There are different amounts of sigma and pi bonds in each type of bond. In a single bond, there is one sigma bond. In a double bond, there is one sigma bond and one pi bond. In a triple bond, there is one sigma bond and two pi bonds

Structural Formula

a formula that shows the arrangement of atoms in the molecule of a compound

How to identify bonding pairs?

bonding pairs are often right next to another symbol and are visibly sharing electrons

HClO3

chloric acid

N2O

dinitrogen monoxide

N2O5

dinitrogen pentoxide

N2F4

dinitrogen tetrafluoride

N2O4

dinitrogen tetroxide

N2O3

dinitrogen trioxide

HBr

hydrobromic acid

HCl

hydrochloric acid

Count and locate the sigma and pi bonds in the following molecules: See photo

line on the left is a pi bond, line on the right is a sigma bond, both lines on the bottom are sigma bonds

How to identify lone pairs?

lone pairs are not connected/bonded with anything

NO2

nitrogen dioxide

NO

nitrogen monoxide

NF3

nitrogen trifluoride

Count and locate the sigma and pi bonds in the following molecules: see photo

one sigma bond between C and C, two pi bonds between C and C, both single lines are sigma bonds (between C and H)

Lewis structure: CCl4

see image

Lewis structure: H2S

see image

SeO2

selenium dioxide