Question 1a

Marks: 2

a)

Two types of covalent bond are sigma and pi bonds.

i)

Describe how a sigma (

σ

) bond is formed

[1]

ii)

Describe how a pi (

π

) bond is formed

[1]

Key Concepts

Sigma Bonds
Pi Bonds

Question 1b

Marks: 2

b)

Describe the difference in the location of the electron dense regions in sigma (

σ

) and pi (

π

) bonds.

[2]

Key Concepts

Sigma Bonds
Pi Bonds

Question 1c

Marks: 2

c)

Deduce the number of sigma (

σ

) and pi (

π

) bonds in methane, CH₄.

[2]

Key Concepts

Predicting the Type of Bonds

Question 1d

Marks: 2

d)

Deduce the number of sigma (

σ

) and pi (

π

) bonds in oxygen, O_2.

[2]

Key Concepts

Predicting the Type of Bonds

Question 2a

Marks: 2

a)

Sulfur can form bonds with six fluorine atoms to form sulfur hexafluoride, SF₆.

i)

How many electrons are in the outer shell of the sulfur in SF₆?

[1]

ii)

State the minimum and maximum numbers of electrons possible in the outer shell of sulfur.

[1]

Key Concepts

Octet Rule Exceptions

Question 2b

Marks: 1

b)

Sulfur has no lone pairs when bonded to fluorines in SF₆. Predict the molecular geometry of sulfur hexafluoride, SF₆.

[1]

Key Concepts

Further VSEPR Theory

Question 2c

Marks: 1

c)

State the F-S-F bond angles in SF₆.

[1]

Key Concepts

Further VSEPR Theory

Question 2d

Marks: 3

d)

Phosphorus pentafluoride, PF₅, is also a molecule with an expanded octet around the central atom.

i)

Draw a Lewis (electron dot) structure for PF₅

[1]

ii)

Predict the molecular geometry of PF₅

[1]

iii)

State the F-P-F bond angle(s)

[1]

Key Concepts

More Lewis Structures
Further VSEPR Theory

Question 3a

Marks: 2

a)

Although noble gases do not normally react, a few compounds are possible. One is xenon tetrafluoride.
Draw the Lewis structure (electron dot) for XeF₄.

[2]

Key Concepts

More Lewis Structures
Further VSEPR Theory

Question 3b

Marks: 2

b)

Predict the molecular geometry and electron domain geometry for the XeF₄ molecule.

[2]

Key Concepts

Further VSEPR Theory

Question 3c

Marks: 2

c)

Predict and explain the F-Xe-F bond angle in XeF₄

[2]

Key Concepts

Further VSEPR Theory

Question 3d

Marks: 2

d)

The formal charge on an atom can be calculated by the following:

FC = (Number of valence electrons) - ½(Number of bonding electrons) - (Number of non-bonding electrons)

Calculate the formal charge on the xenon and the fluorines in xenon tetrafluoride, XeF₄.

[2]

Key Concepts

Formal Charge

Question 4a

Marks: 2

a)

Draw a Lewis (electron dot) structure for carbon dioxide, CO₂.

[2]

Key Concepts

Lewis structures

Question 4b

Marks: 2

b)

Predict the molecular geometry and the O-C-O bond angle in carbon dioxide, CO₂.

[2]

Key Concepts

Predicting Shapes & Bond Angles

Question 4c

Marks: 2

c)

An alternative way to draw the carbon dioxide molecule is:

co2-resonance-lewis-structure-ib-hl-sq-14-1-4c

Identify the formal charge on each of the oxygen atoms.

[2]

Key Concepts

Formal Charge

Question 4d

Marks: 2

d)

State which of the Lewis structures, that from part a) or part c), is preferable and explain your choice.

[2]

Key Concepts

Applying Formal Charge

DP IB Chemistry: HL

Topic Questions

14.1 More Structures & Shapes

Question 1a

Key Concepts

Question 1b

Key Concepts

Question 1c

Key Concepts

Question 1d

Key Concepts

Question 2a

Key Concepts

Question 2b

Key Concepts

Question 2c

Key Concepts

Question 2d

Key Concepts

Question 3a

Key Concepts

Question 3b

Key Concepts

Question 3c

Key Concepts

Question 3d

Key Concepts

Question 4a

Key Concepts

Question 4b

Key Concepts

Question 4c

Key Concepts

Question 4d

Key Concepts

Resources

Members

Company

Quick Links