Covalent Bonding and Molecular Structure (key) AX2: CO2 1. What is the O–C–O bond angle?

180° 2. Which element is more electronegative, carbon, or oxygen?

Oxygen 3. Would you expect CO2 to be a polar or a non-polar molecule? Explain.

Polar. Even though it is composed of polar bonds, the two bonds are located opposite one another and their affect will cancel each other.

Carbon Dioxide (CO2)

O C O O C O Valence Electrons: 16 Hybridization: C = sp, O = sp2 Electronic Geometry: Linear Molecular Geometry: Linear

Lewis Dot Structure

Perspective Drawing

AX3: BF3, NO3-, CO3

2- 1. What is the F–B–F bond angle in BF3?

120° 2. What is the O–N–O bond angle in NO3

-? 120°

3. What is the O–C–O bond angle in CO32-?

120° 4. Is the electron density in the B-F bond of BF3 oriented closer to fluorine, or to boron?

Fluorine 5. What is the average bond order for the N-O bonds in the nitrate ion?

11/3 6. What is the average bond order for the C-O bonds in the carbonate ion?

11/3

Boron Trifluoride (BF3)

F B F

F

FB

F

F

Valence Electrons: 24 Hybridization: B = sp2, F = sp3 Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar

Lewis Dot Structure

Perspective Drawing

Nitrate (NO3-)

O N O

O-

O

NO

O-

Valence Electrons: 24 Hybridization: N = sp2, O = sp2 Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar

Lewis Dot Structure

(1 of 3 resonance structures)

Perspective Drawing

Carbonate (CO32-)

O C O

O2-

O

CO

O2-

Valence Electrons: 24 Hybridization: C = sp2, O = sp2 Electronic Geometry: Trigonal Planar Molecular Geometry: Trigonal Planar

Lewis Dot Structure

(1 of 3 resonance structures)

Perspective Drawing

AX2E: SO2, SnCl2 1. What is the O–S–O bond angle in SO2?

< 120° 2. What is the Cl–Sn–Cl bond angle in SnCl2?

< 120° 3. Which bond is longer, the S–O bond in SO2 or the Sn–Cl bond in SnCl2? Explain.

Sn – Cl is a longer bond. It is composed of larger atoms, therefore the distance between the nuclei of the bonded atoms will be greater.

4. Which bond angle would you expect to be smaller, O–S–O or Cl–Sn–Cl? Explain. The Cl – Sn – Cl will be a smaller bond angel. There are two reasons for this. First, the S – O bonds are double bonds, so they repel with a greater force and therefore will not be able to be pushed as close together by the lone pair as the single Sn – Cl bonds in SnCl2. Second, the Sn – Cl bond is polar resulting in the electron density of those bonds being pulled away from the Tin resulting in less repulsion and can therefore be pushed closer together.

Sulfur Dioxide (SO2)

O S O OS

O Valence Electrons: 18 Hybridization: S = sp2, O = sp2

Electronic Geometry: Trigonal Planar Molecular Geometry: Bent

Lewis Dot Structure

Perspective Drawing

Tin (II) Chloride (SnCl2)

Cl Sn Cl Cl Sn Cl Valence Electrons: 18 Hybridization: S = sp2, Cl = sp3

Electronic Geometry: Trigonal Planar Molecular Geometry: Bent

Lewis Dot Structure

Perspective Drawing

AX4: CH4, NH4+, CH3Cl

1. What is the H–C–H bond angle in CH4? 109.5°

2. What is the H–N–H bond angle in NH4+?

109.5° 3. What is the H–C–Cl bond angle in CH3Cl?

<109.5° 4. What is the H–C–H bond angle in CH3Cl?

>109.5° 5. Which one of these molecules is polar? Using your perspective drawing, draw an arrow

toward the more negative side of the molecule.

HC

H H

Cl

CH3Cl is polar

6. In CH3Cl, which bond is longer, C–H or C–Cl?

C – Cl is a longer bond. This is due to the size of Chlorine versus Hydrogen

Methane (CH4), aka “Carbon tetrahydride”

C

H

H

H

H

H CH

H

H

Valence Electrons: 8 Hybridization: C = sp3

Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral

Lewis Dot Structure

Perspective Drawing

Ammonium (NH4+)

N

H

H

H

H

+

H NH

H

H

+

Valence Electrons: 8 Hybridization: N = sp3

Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral

Lewis Dot Structure

Perspective Drawing

Methyl Chloride (CH3Cl)

C

Cl

H

H

H

H CH

Cl

H

Valence Electrons: 14 Hybridization: C = sp3, Cl = sp3 Electronic Geometry: Tetrahedral Molecular Geometry: Tetrahedral

Lewis Dot Structure

Perspective Drawing

AX3E: NF3, NH3, H3O+ 1. What is the F–N–F bond angle in NF3?

<109.5° 2. What is the H–N–H bond angle in NH3?

<109.5° 3. What is the H–O–H bond angle in H3O+?

<109.5° 4. Would you expect the electron density from the lone pair to be closer to the nitrogen in NF3,

or in NH3? Explain. The lone pair will be closer to the nitrogen in NF3. The nitrogen in NF3 is partially positive and will therefore attract the lone pair more than the partially negative Nitrogen in NH3.

5. Which bond angle do you expect to be smaller, F–N–F in NF3 or H–O–H in H3O+? Explain. The F – N – F bond angle will be smaller. The Fluorine atoms attract electron density away from the center atom (N) and therefore repel less. The lone pair on the Nitrogen will push the Fluorine atoms closer together.

Nitrogen Trifluoride (NF3)

F N F

F

F N

F F

Valence Electrons: 26 Hybridization: N = sp3, F = sp3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal

Lewis Dot Structure

Perspective Drawing

Ammonia (NH3)

H N H

H

H NH H

Valence Electrons: 8 Hybridization: N = sp3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal

Lewis Dot Structure

Perspective Drawing

Hydronium (H3O+)

H O H

H +

H OH H

+

Valence Electrons: 8 Hybridization: O = sp3 Electronic Geometry: Tetrahedral Molecular Geometry: Trigonal Pyramidal

Lewis Dot Structure

Perspective Drawing

AX2E2: H2O, CH3–O–CH3 1. What is the H–O–H bond angle in H2O?

< 109.5° 2. What is the C–O–C bond angle in CH3-O-CH3?

< 109.5° 3. What is the H–C–H bond angle in CH3-O-CH3?

> 109.5° 4. Do you expect the bond angle H–O–H to be smaller in H2O, or in H3O+? Explain.

The H – O – H bond angle in H2O will be smaller. There are two lone pairs pushing the Hydrogen atoms together which will have a greater affect thatn only one lone pair found in H3O+.

Water (H2O)

H O H O

H

H

Valence Electrons: 20 Hybridization: O = sp3, Electronic Geometry: Tetrahedral Molecular Geometry: Bent

Lewis Dot Structure

Perspective Drawing

Dimethyl Ether (CH3 – O – CH3)

C

H

H

H

O C

H

H

H

H CH

H

OC

HH

H

Valence Electrons: 20 Hybridization: O = sp3, C = sp3 Electronic Geometry(s): Carbon – Tetrahedral Oxygen - Tetrahedral Molecular Geometry(s): Carbon – Tetrahedral Oxygen - Bent

Lewis Dot Structure

Perspective Drawing

AX5: PF5, SOF4 1. What is the FA–P– FA bond angle in PF5?

180° 2. What is the FA–P– FE bond angle in PF5?

90° 3. What is the FE–P– FE bond angle in PF5?

120° 4. What is the FE–S– O bond angle in SOF4?

> 120° 5. What is the FA–S– O bond angle in SOF4?

> 90° 6. What is the FE–S– FE bond angle in SOF4?

< 120° 7. What is the FE–S– FA bond angle in SOF4?

< 90° 8. Is the oxygen in SOF4 located in an axial or an equatorial position? Why is this?

Equatorial. The equatorial positions allow for more space to minimize repulsion. For this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially.

9. Which bond in SOF4 has the shortest bond length? The S=O will be the shortest. Double bonds are shorter than single bonds.

Phosphorus Pentafluoride (PF5)

PF F

F

F F

FP

F

F

F

F

Valence Electrons: 40 Hybridization: P = sp3d, F = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Trigonal Bipyramidal

Lewis Dot Structure

Perspective Drawing

Thionyl Tetrafluoride (SOF4)

SF F

O

F F

FS

F

F

F

O

Valence Electrons: 40 Hybridization: S = sp3d, F = sp3, O = sp2 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Trigonal Bipyramidal

Lewis Dot Structure

Perspective Drawing

AX4E: SF4, IF4+

1. What is the FA–S– FA bond angle in SF4? The angle will not be 180°, greater or less than depends on your point of view.

2. What is the FA–S– FE bond angle in SF4? < 90°

3. What is the FE–S– FE bond angle in SF4? < 120°

4. What is the FA–I– FA bond angle in IF4+?

The angle will not be 180°, greater or less than depends on your point of view. 5. What is the FA–I– FE bond angle in IF4

+? < 90°

6. What is the FE–I– FE bond angle in IF4+?

< 120° 7. Does the lone pair of electrons in SF4 occupy an axial or an equatorial position? Explain.

The lone pair will occupy an equatorial position. The equatorial positions allow for more space to minimize repulsion. For this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially

Sulfur Tetrafluoride (SF4)

F S

F

F

F

FS

F

F

F

Valence Electrons: 34 Hybridization: S = sp3d, F = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Seesaw

Lewis Dot Structure

Perspective Drawing

Iodine Tetrafluoride Ion (IF4+)

F I

F

F

F +

FI

F

F

F

+

Valence Electrons: 34 Hybridization: I = sp3d, F = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Seesaw

Lewis Dot Structure

Perspective Drawing

AX3E2: ClF3 1. What is the FA–Cl– FA bond angle in ClF3? The angle will not be 180°, greater or less than depends on your point of view. 2. What is the FA–Cl– FE bond angle in ClF3? < 90° 3. Why are you not being asked to predict the FE–Cl– FE bond angle?

There is only one equatorial position occupied, so there is not an FE– Cl–FE to be measured. 4. Which bond do you expect to be longer, FA–Cl or FE–Cl? Explain.

Cl

FA

FA

FE

The FA – Cl bond will be longer. Each of the three bonds is a polar bond. When a bond is polar it shrinks due to an increase in ionic character. Since the two FA – Cl bonds are roughly 180° from one another, the polarity is cancelled to an extent, and so the bond will shrink less. There is no opposing polar bond for the FE – Cl so it will be a more polar and therefore shrink more.

Chlorine Trifluoride (ClF3)

F Cl

F

F

Cl

F

F

F

Valence Electrons: 28 Hybridization: Cl = sp3d, F = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: T - Shaped

Lewis Dot Structure

Perspective Drawing

AX2E3: I3-, IF2-

1. What is the I–I–I bond angle in I3-? 180°

2. What is the F–I–F bond angle in IF2-?

180° 3. Which bond length do you expect to be longer, the I–I bond in I3- or the F–I one in IF2

-? Explain. I – I bond will be longer. It is composed of larger atoms.

4. Why doesn't either fluorine atom in IF2- occupy an equatorial position?

The equatorial positions allow for more space to minimize repulsion. For this reason, the higher repulsion groups (lone pairs, double bonds) will be placed equatorially. Since this molecule contains three lone pairs, each of the lone pairs will occupy the three equatorial positions.

Triiodide Ion (I3-)

I

I

I

-

I

I

I

-

Valence Electrons: 28 Hybridization: I (center) = sp3d I (outer) = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Linear

Lewis Dot Structure

Perspective Drawing

Iodine Difluoride Ion (IF2-)

I

F

F

-

I

F

F

-

Valence Electrons: 28 Hybridization: I = sp3d, F = sp3 Electronic Geometry: Trigonal Bipyramidal Molecular Geometry: Linear

Lewis Dot Structure

Perspective Drawing

AX6: SF6, IOF5 1. What is the F1–S–F2 bond angle in SF6?

90° 2. What is the F1–S–F3 bond angle in SF6?

180° 3. What is the O–I–F1 bond angle in IOF5?

>90° 4. What is the F1–I–F2 bond angle in IOF5?

<90° 5. What is the F1–I–F5 bond angle in IOF5?

<90° 6. What is the F2–I–F5 bond angle in IOF5?

<90° 7. Are all of the fluorine atoms in SF6 equivalent? Why?

Yes. Each fluorine atom is 90° from four other fluorine atoms and 180° from one other fluorine.

8. Would you expect angles F1–I–F2 and F2–I–F3 in IOF5 to be equal? Why or why not? Those angles will be equivalent. F1 and F2 are adjacent to one another, and both are adjacent to the double bonded oxygen atom. This is also the case for F2 and F3. For this reason it can be said the bond angles are feeling the same influence.

Sulfur Hexafluoride (SF6)

S

F

F

F

F

F

F

S

F

F

F

F

F

F

Valence Electrons: 48 Hybridization: S = sp3d2, F = sp3 Electronic Geometry: Octahedral Molecular Geometry: Octahedral

Lewis Dot Structure

Perspective Drawing

Iodine Oxide Pentafluoride (IOF5)

I

O

F

F

F

F

F

I

O

F

F

F

F

F

Valence Electrons: 48 Hybridization: I = sp3d2, O = sp2, F = sp3 Electronic Geometry: Octahedral Molecular Geometry: Octahedral

Lewis Dot Structure

Perspective Drawing

AX5E: BrF5, TeF5-

1. What is the F1–Br–F2 bond angle in BrF5? <90°

2. What is the F1–Br–F3 bond angle in BrF5? All that can be said is the angle will not be 180°. To say it is greater than or less than 180° depends on how you view the molecule. If the molecule were viewed from above according to figure 3 below the angle would be <180°. If the molecule were viewed from below according to figure 3 below the angle would be >180°.

F4Br

F3

F1 F2

F5

Figure 1

Rotate clockwise 90°

F1 BrF3

F5F4

F2

Figure 2

Focus on just F1 – Br – F2 bond

F1 BrF3

F5F4

F2

<180

>180

Figure 3

3. What is the F1–Br–F5 bond angle in BrF5?

<90° 4. What is the F1–Te–F2 bond angle in TeF5

-? <90°

5. What is the F1–Te–F3 bond angle in TeF5-?

All that can be said is the angle will not be 180°. To say it is greater than or less than 180° depends on how you view the molecule. If the molecule were viewed from above according to figure 3 below the angle would be <180°. If the molecule were viewed from below according to figure 3 below the angle would be >180°.

F4Te

F3

F1 F2

F5

Figure 1

Rotate clockwise

90° F1 TeF3

F5F4

F2

Figure 2

Focus on just

F1 – Br – F2 bond

F1 TeF3

F5F4

F2

<180

>180

Figure 3

6. What is the F1–Te–F5 bond angle in TeF5

-? <90°

7. Which bond in BrF5, Br–F1 or Br–F5, do you expect to be longer? Explain. The Br – F1 bond will be longer than the Br – F5. Each bond is a polar bond. When a bond is polar it shrinks due to an increase in ionic character. Since the Br – F1 bond has another equivalent bond oriented roughly 180° from it the polarity is cancelled to an extent, and so the bond will shrink less. There is no opposing polar bond for the Br – F5 so it will be a more polar and therefore shrink more.

F4Br

F3

F1 F2

F5

Figure 1

Rotate clockwise

90° F1 BrF3

F5F4

F2

Figure 2

8. Would you expect bond Br–F1 in BrF5 to have a bond length that is shorter, longer, or the

same as the length of bond Te–F1 in TeF5-? Explain.

The Te – F1 will be a longer bond than Br – F1. This is due to the size of the Tellurium atom versus the Bromine atom.

Bromine Pentafluoride (BrF5)

Br

FF

F

F

F Br

FF

F

F

F

Valence Electrons: 42 Hybridization: Br = sp3d2, F = sp3 Electronic Geometry: Octahedral Molecular Geometry: Square Pyramidal

Lewis Dot Structure

Perspective Drawing

Tellurium Pentafluoride Ion (TeF5-)

Te

FF

F

F

F

-

Te

FF

F

F

F

-

Valence Electrons: 42 Hybridization: Te = sp3d2, F = sp3 Electronic Geometry: Octahedral Molecular Geometry: Square Pyramidal

Lewis Dot Structure

Perspective Drawing

AX4E2: ICl4- 1. What is the Cl1–I–Cl2 bond angle in ICl4-?

90° 2. What is the Cl1–I–Cl3 bond angle in ICl4-?

180° 3. Why are the two lone pairs ICl4- on opposite vertices of the molecule?

The lone pairs require more space since they repel more than bonded pairs. For this reason the two lone pairs will be as far from one another as possible to minimize repulsion.

4. Would you expect Cl1–I to have a shorter, longer, or the same bond length as Cl2–I? Explain. The bonds will be the same length. The positions of the chlorine atoms (Cl1 and Cl2) are equivalent to one another.

Iodine Tetrachloride Ion (ICl4-)

ICl

Cl

Cl

Cl

-

ICl

Cl

Cl

Cl

-

Valence Electrons: 42 Hybridization: I = sp3d2, Cl = sp3 Electronic Geometry: Octahedral Molecular Geometry: Square Planar

Lewis Dot Structure

Perspective Drawing