Intermolecular Forces, Electronegativity & Bond Properties (CIE A Level Chemistry)

Paperclips have a higher density than water. However, if a paperclip is lowered carefully onto the surface of water, the paperclip can float. When a drop of liquid soap is added to the water, the paperclip sinks.

Suggest explanations for these observations.

Ammonia is highly soluble in water. Draw diagrams to show the two ways that intermolecular forces can form between a molecule of water and a molecule of ammonia to explain this.

NH₃, HCl and F₂ all exist as gases at room temperature and pressure.

NH₃ has the highest boiling point of -33 °C .

Predict whether HCl or F₂ has the lowest boiling point and explain why there is a difference between their boiling points.

Ammonia, NH₃, and methane, CH₄, are the hydrides of elements which are next to one another in the Periodic Table.

In the boxes below, draw the ‘dot-and-cross’ diagram of a molecule of each of these compounds.

Show outer electrons only.

State the shape of each molecule.

Ammonia is polar whereas methane is non-polar. The physical properties of the two compounds are different.

[2]

State one physical property of ammonia which is caused by its polarity.

When ammonia gas is mixed with hydrogen chloride, white, solid ammonium chloride is formed.

State each type of bond that is present in one formula unit of ammonium chloride and how many of each type are present.

You may draw diagrams.