4.2 Resonance, Shapes & Giant Structures

Tetrafluoroethene, C₂F₄, and tetrafluorohydrazine, N₂F₄, are fluorides of adjacent elements in the Periodic Table.

Draw the Lewis (electron dot) structures for C₂F₄ and N₂F₄ showing all valance electrons.

[2]

Predict and explain the F-C-F bond angle in tetrafluoroethene and the F-N-F bond angle in tetrafluorohydrazine.

[5]

Tetrafluorohydrazine is a polar molecule but tetrafluoroethene is not.

Explain the difference in molecular polarity.

[4]

Draw the Lewis (electron dot) structure of the carbonate ion, CO₃^2-.

[3]

Deduce the number of possible resonance structures for the carbonate ion, CO₃^2-, and draw two of them.

[3]

Discuss how the bonding in the carbonate ion, CO₃^2-, evidences the presence of the resonance structures.

[3]

Organic molecules can also show resonance. The methanoate ion, HCOO^-, shows similar resonance forms to the carbonate ion, CO₃^2-.

The corresponding organic acid, methanoic acid, also has resonance structures.

Draw another resonance structure of methanoic acid.

[2]

Some of the physical and structural properties of diamond and graphite are shown below:

 

Predict the bond order in both diamond and graphite.

[2]

Graphene has the structure of a single layer of graphite. 

Suggest, giving a reason, the electron mobility of graphene compared to graphite.

[2]

Graphite is a layered giant structure, containing London dispersion forces between the layers, whereas diamond has covalent bonds across all planes.

Describe and explain, based on structure and bonding, the differences expected when each of graphite and diamond are moved across a paper surface.

[6]