This question is about H₂O.

State the strongest type of interaction between molecules of water.

Draw a diagram to show hydrogen bonding between two molecules of H₂O. 

Include all lone pairs and partial charges in your diagram. 

Label the hydrogen bond.

Hydrogen bonding in ice causes ice to have several anomalous properties, including:

• a lower density than water
• a relatively high melting point.
• a high surface tension

Explain why hydrogen bonding causes ice to have these anomalous properties.

This question is about the element hydrogen and its compounds.

Lithium amide (LiNH₂) contains the amide ion, NH₂^-. 

Draw the shape of the amide ion, NH₂^-

Include any lone pairs and give the value of the bond angle.

Describe the requirements for hydrogen bonding between two molecules, A and B.

The table below shows the boiling points of ammonia, NH₃, and hydrogen, H₂.

Explain the difference in boiling points.

State the meaning of the term electronegativity. 

The table below shows the Pauling electronegativity values of some Period 3 elements.

Suggest why the electronegativity of the elements increases from sodium to chlorine.

Deduce the type of bonding in sulfur hexachloride, SCl₆.

Explain your reasoning, using the table of electronegativity values above.

Draw the shape of a molecule of SF₆. Include a value of the F-S-F bond angle. 

Explain why the shape of a molecule of SF₆ is octahedral.

Draw a dot-and-cross diagram to show the bonding in a molecule of SF₆. 

This question is about intermolecular forces.

The table below shows some electronegativity values of some elements.

Using the data in the table above, predict the formula of the compound with the most polar bonds formed from two of these elements.

The Si-Cl bond is polar.

Explain why SiCl₄ is not a polar molecule.

State the strongest type of intermolecular force that exists between molecules of SiCl₄. 

Explain how induced dipole-dipole forces in a sample of SiCl₄. 

This question is about the Group 3 element boron. 

Boron trifluoride can react with a fluoride ion as shown by the equation;

BF₃  + F^-  ➔ BF₄^-

Draw a diagram to show the shape of the BF₃ molecule.

State its shape. 

Explain why the BF₃ molecule has the shape that you have drawn in part a).

Draw a diagram to show the shape of the BF₄^- ion.

State its shape.

Name the type of bond formed in the reaction between BF₃ and F^- to form BF₄^-.

Explain how this bond is formed in terms of electrons involved.

The diagram below represents a molecule of hydrogen peroxide.

Predict a value for the H-O-O bond angle.

Hydrogen peroxide dissolves in water.

State the strongest type of interaction that occurs between molecules of hydrogen peroxide and water.

Draw a diagram to show how one molecule of hydrogen peroxide interacts with one molecule of water.

Include all lone pairs and partial charges in your diagram.

Explain, in terms of electronegativity, why the boiling point of H₂O₂ is higher than H₂S₂.

Draw a diagram to show the shape of a molecule of ammonia. Include any lone pairs of electrons and give the value of the bond angle.

What is the name of the shape of the ammonia molecule, NH₃?

Ammonia, NH₃, can react with a hydrogen ion,  H⁺, to form an ammonium ion, NH₄⁺, which contains a dative covalent bond.

Explain how the dative covalent bond in NH₄⁺ is formed.

State the new shape and bond angle of the ammonium ion.

Ammonia reacts with aluminium chloride as shown by the equation:

NH₃ + AlCl₃ ➔ H₃NAlCl₃

Draw a diagram to illustrate the shape of a molecule of AlCl₃.

Give the value of the bond angle.

Name the type of bond formed between N and Al in H₃NAlCl₃.

Explain how the value of the Cl-Al-Cl bond angle in AlCl₃ changes, if at all, on formation of the compound H₃NAlCl₃.

Trichloroethane, C₂HCl₃, is a polar molecule.

Annotate the diagram below to show the direction of the dipole in a molecule of trichloroethene. 

Include partial charges.

The boiling points of trichloroethene, C₂HCl₃, and tetrachloroethene, C₂Cl₄, are shown in the table below.

Suggest, in terms of intermolecular forces, why C₂Cl₄ has a higher boiling point than C₂HCl₃.