ReviewWrite the electron configuration for an atom

of carbon and chlorine.Determine the empirical and molecular

formula for a compound consisting of 7.8% carbon and 92.2% chlorine. The molecular mass of the compound is 154 g/mole.

Write the name for the compound.

What is a covalent bond?A covalent bond forms between two atoms that are

sharing one or more pair of electrons.Usually occurs when the electronegativity difference

between the two elements is small (<1.7)Covalent bonds form between two nonmetals.The bond results from an overlapping of orbitals.A covalent bond is a weaker bond than an ionic bond.Properties of compounds resulting from a covalent

bond include: low melting point, gases or liquids at room temp (some are soft solids), do not conduct electricity, many are insoluble in water.

Naming covalently bonded compounds.The first element is named according to the

element name.An –ide ending is added to the name of the

second element.Numerical prefixes are used to indicate the

number of each type of atom present.

Numerical PrefixesPrefix Number*Mono (only used with the second element)

1

Di 2Tri 3Tetra 4Pent 5Hex 6Hept 7Oct 8Non 9Dec 10

Name the following compoundsCO2CON2ONONO2N2O3N2O4N2O5PCl5PCl3SF6

Write the formulas for the following compounds:Sulfur trioxideDioxygen difluorideTetraphosphorus decaoxideDiboron trioxideArsenic pentafluorideSilicon dioxideMonohydrogen dioxideNitrogen trihydride

Types of Covalent BondsA single covalent bond occurs when one pair

of electrons (2 electrons) are shared between two atoms.

A double covalent bond occurs when two atoms share two pairs (4 electrons) of electrons.

A triple covalent bond occurs when two atoms share three pairs (6 electrons) of electrons.

Drawing Lewis Dot StructuresLewis dot structures can be drawn to represent

the bonding that occurs within a covalent molecule.

Atoms of hydrogen and halogens can only form one single bond each. (They only need to share 1 electron to form a complete octet).

Lines represent the shared pairs of electrons or the chemical bonds between atoms. Unshared pairs are represented by dots or a line.

ExampleDraw the Lewis Dot Structure for CCl4

Example #2Draw the Lewis dot structure for a molecule

of NH3.

Example #3Draw the Lewis dot structure for H2O.

For molecules involving atoms other than halogens or hydrogenUse the formula “N-A = S” to determine the

number and type of bonds within the molecule.N represents the total number of valence electrons

needed by all atoms to have a complete octet.A represents the total number of valence electrons

available in all atoms within the molecule.S represents the total number of electrons that

will need to be shared in order to form complete octets for each atom.

Divide the number shared by 2 to determine the number of bonds that will form.

Draw the Lewis dot structure for O2.N= 16A=12S=44/2=2 Therefore, 2 bonds are needed (or 4

electrons need to be shared) in order for this molecule to form.

Draw the Lewis dot structure for N2.Step 1: Solve the equation “N-A = S”Step 2: Divide “S” by 2.Step 3: Draw the general structure of the

molecule Step 4: Fill in the bonds.Step 5: Fill in the remaining valence

electrons so that all atoms have a stable arrangement (8 electrons)

Draw the Lewis dot structure for CO2

Step 1: 24 – 16 = 8Step 2: 8/2= 4Step 3:

Draw the Lewis dot structure for HCN

Step 1: 18-10 = 8Step 2: 8/4 = 2Step 3:

Homework:Name and Draw Lewis Dot Structures for the

following molecules:1) PCl3 7) HCl2) OF2 8) CS23) N2 9) H2CO4) Br2 10) C2H25) O26) SiF4

Polar vs Nonpolar BondsIf the electrons are shared equally, it is called

a nonpolar covalent bond. (This type of bond only occurs if the electrons are shared between identical atoms)

If the electrons are shared unequally, it is called a polar covalent bond.

Polar and Nonpolar MoleculesMolecules can also be polar and nonpolar.Molecules are nonpolar if:

1) the bonds are nonpolar2) the polar bonds are arranged symmetrically

Molecules are polar if the polar bonds are arranged asymmetrically.

Lewis Dot DiagramsCl2LinearNonpolar bondsNonpolar moleculeChlorine

Lewis Dot DiagramsH2OBentPolar bondsPolar moleculeDihydrogen monoxide

Lewis Dot DiagramsNH3Trigonal pyramidalPolar bondsPolar moleculeNitrogen trihydride

Lewis Dot DiagramsCH4TetrahedralPolar bondsNonpolar moleculeCarbon tetrahydride

In covalent compounds, atoms become stable by ___ their valence electrons.

95%

5% 1. transferring2. sharing

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

A ___ covalent bond is the result of an equal share of electrons by both atoms.

89%

11% 1. polar2. nonpolar

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

A cation has a ___ charge.

0%

100% 1. positive2. negative

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

When an atom ___ electrons, it becomes positively charged.

95%

5% 1. gains2. loses

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

In the formula CO2, the number 2 is called a ___.

100%

0%

0%

0% 1. superscript2. oxidation number3. charge4. subscript

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

What is the correct name for PCl3?

0%

100%

0%

0% 1. Monophosphorus trichloride2. Phosphorus chloride3. Phosphorus trichloride4. Traphosphorus chloride

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

What is the correct name for Li2O?

26%

26%

37%

11% 1. Lithium oxide2. Dilithium oxide3. Lithium (II) oxide4. Lithium dioxide

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Which is not a diatomic molecule?

56%

11%

22%

11% 1. Fluorine2. Nitrogen3. Bromine4. Boron

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Which element is a nonmetal?

0%

89%

0%

11% 1. Boron2. Lithium3. Carbon4. Magnesium

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Which element has 7 valence electrons?

0%

100%

0%

0% 1. Boron2. Nitrogen3. Fluorine4. Manganese

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Noble gases are stable because they have __ valence electrons.

100%

0%

0%

0% 1. 22. 43. 64. 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

The noble gases are in which block of the periodic table?

11%

22%

61%

6% 1. s2. p3. d4. f

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Electrons have what charge?

0%

16%

84% 1. -12. +13. 0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

How many valence electrons are in an atom of oxygen?

0%

100%

0%

0% 1. 22. 43. 64. 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

How many shared pairs are present?

0%

0%

100%

0% 1. 12. 23. 34. 4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

How many electrons are not shared?

68%

0%

26%

5% 1. 12. 23. 34. 4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

How many single bonds are present?

32%

0%

63%

5% 1. 12. 23. 34. 4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Are the bonds polar or nonpolar?

26%

74% 1. Polar2. Nonpolar

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

What is the shape of the molecule?

16%

0%

63%

21% 1. Linear2. Bent3. Trigonal pyramidal4. Tetrahedral

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Is the molecule polar or nonpolar?

37%

63% 1. Polar2. Nonpolar

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

10 ml of the substance has a mass of 9 g. What is its density?

0%

16%

5%

79% 1. 0.9 g/ml2. 1.0 g/ml3. 1.1 g/ml4. 19 g/ml

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

What is the percent oxygen in the substance?

6%

22%

61%

11% 1. 11%2. 33%3. 67%4. 89%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23

Double and Triple BondsA double covalent bond occurs when two

atoms share two pairs (4 electrons) of electrons.

A triple covalent bond occurs when two atoms share three pairs (6 electrons) of electrons.

Examples of compounds consisting of double bonds.CO2O2C2H4

Examples of compounds consisting of triple bonds.N2HCNC2H2