1.	Hydrogen forms compounds with most non-metallic elements and with some metals.
(a)	Calculate the empirical formula of the compound used in the manufacture of artificial rubber which has the following composition by mass.
	Hydrogen 11.1%	Carbon 88.9%

(3)
 
(b)	The boiling temperatures of hydrogen chloride and hydrogen iodide are:
	Hydrogen chloride	–85ºC
	Hydrogen iodide 	–35ºC
	Explain why hydrogen iodide has a higher boiling temperature than hydrogen chloride.
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(2)
 
(c)	Draw and explain the shapes of:
(i)	the PH3 molecule;

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(2)

(ii)	the AlH4– ion.

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(2)
 
(d)	Calculate the number of molecules in 8.0 cm3 of gaseous phosphine, PH3, at room temperature and pressure.
	(The molar volume of a gas at room temperature and pressure should be taken as 2.4 × 104 cm3 mol–1.  The Avogadro constant is 6.0 × 1023 mol–1.)

(2)
(Total 11 marks)

2.	Consider the following shapes

	Indicate by a letter (A, B, C or D) the shape of the following ions or molecules:
(i)	H2O ................................
(ii)	NH3 ................................
(iii)	CO2 ................................
(iv)	CO .............................
(Total 4 marks)

3.	Deduce and draw the shapes of the following molecules or ions. Suggest a value for the bond angle in each case. Give a brief explanation of why each has the shape you give.
(a)	SF6

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(3)
 
(b)	PH3

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(3)

(c)	PF

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(3)
(Total 9 marks)

4.	(a)	Boron forms the chloride BCl3. Draw a dot-and-cross diagram for BCl3.

(1)
 
(b)	(i)	Draw the shape of the BCl3 molecule.

(1)

(ii)	Explain why BCl3 has this shape.
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(2)
 
(c)	(i)	The B¾Cl bond is polar due to the different electronegativity of the atoms. Explain what is meant by the term electronegativity.
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(2)
(ii)	The B¾Cl bond is polar. Explain why BCl3 is not a polar molecule.
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(2)
(Total 8 marks)

5.	(a)	Draw the shape of each of the following molecules and mark on the diagram a value for the bond angle in each case.
(i)	CH4

(2)

(ii)	NH3

(2)
 
(iii)	BeCl2

(2)
 
(b)	Name the strongest type of intermolecular force present in separate samples of each of the following substances:
(i)	CH4
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(1)
(ii)	HF
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(1)

(c)	State and explain which of the substances CH4 and HF has the higher boiling temperature.
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(2)
(Total 10 marks)

6.	Nitrogen and phosphorus are in the same group of the Periodic Table. Phosphorus and hydrogen form the compound phosphine, PH3, and nitrogen and hydrogen form ammonia, NH3.
(a)	(i)	State the number of bond pairs and lone pairs of electrons in a molecule of phosphine.
Bond pairs of electrons: .....................   Lone pairs of electrons: ....................
(2)
 
(ii)	Use your answer to (i) to draw the shape of the molecule and indicate on your diagram the approximate HPH bond angle that you would expect.

(2)
 
(b)	The boiling temperature of ammonia is –33 °C and that of phosphine –88°C.
(i)	List all the intermolecular forces that exist between molecules of ammonia.
………….……………….……………………………………………………..
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(2)

(ii)	Explain why the boiling temperature of phosphine is lower than that for ammonia.
………….……………….……………………………………………………..
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………….……………….……………………………………………………..
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(2)
 
(c)	Ammonia forms a dative covalent bond with H+ ions to form the ammonium ion, NH4+.
(i)	Explain what is meant by the term dative covalent bond.
………….……………….……………………………………………………..
………….……………….……………………………………………………..
(2)
 
(ii)	What part of the ammonia molecule enables it to form such a bond?
………….……………….……………………………………………………..
(1)
 
(iii)	State and explain the shape of the ammonium ion, NH4+.
………….……………….……………………………………………………..
(3)
(Total 14 marks)

7.	(a)	State the shape of a water molecule and explain why it has this shape.
Shape .....................................................................................................................
Explanation ............................................................................................................
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(3)
 
(b)	Predict the shape of the H3O+ ion and draw a diagram to illustrate its shape.
Shape ....................................................................................................................
Diagram

(2)
 
(c)	(i)	Use water as an example to explain what is meant by the term hydrogen bond.
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(3)

(ii)	State the difference in density between solid ice and liquid water and describe how the presence of hydrogen bonds accounts for this.
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(3)
(Total 11 marks)

8.	(a)	Define the term oxidising agent in terms of electron transfer, and suggest which element in Group 7 is the strongest oxidising agent.
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(2)
 
(b)	Chlorine can react with hydroxide ions to produce chloride ions, chlorate(l) ions and water.
(i)	Write the ionic equation for this reaction. There is no need to include state symbols.
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(2)
(ii)	What type of reaction is taking place in (b)(i)?
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(1)

(c)	(i)	Write an equation for the reaction between concentrated sulphuric acid and solid sodium chloride.
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(1)
(ii)	State ONE observation that you would make.
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(1)
 
(d)	Draw the shapes of the following molecules, and mark on the diagram the value of the bond angles in each case.
(i)	BCl3

(2)

(ii)	PCl5

(3)
(Total 12 marks)

9.	Phosphorus(III) chloride, PCl3, can be formed by the reaction of phosphorus and chlorine.
2P(s)  + 3Cl2(g)  ®  2PCl3(s)
(a)	(i)	Calculate the maximum mass of phosphorus(III) chloride, PCl3, which could be obtained from 93.0 g of phosphorus.

(3)

(ii)	Calculate the minimum volume of chlorine required to react completely with 93.0 g of phosphorus.
[One mole of gas occupies a volume of 24.0 dm3 under the conditions of the experiment].

(2)
 
(iii)	Identify the oxidising agent in the above reaction and explain your answer.
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(2)
 
(b)	(i)	Draw a dot and cross diagram for a molecule of PCl3.

(2)

(ii)	Draw the predicted shape of a PCl3 molecule and mark on the diagram a value for the bond angle.

(2)
 
(c)	Suggest the name for the shape of the PCl4+ ion.
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(1)
(Total 12 marks)

10.	(a)	State the type of bonding in the following substances and draw diagrams to illustrate their 3-dimensional structures.
	Diamond
	Bonding ..............................................................
	Diagram

(3)
 
(b)	Explain why sodium chloride conducts electricity when molten but not when solid.
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(2)
(Total 5 marks)

11.	Phosphine, PH3, is a hydride of the Group 5 element, phosphorus.
(a)	(i)	Draw a ‘dot-and-cross’ diagram of a phosphine molecule. You should include only outer shell electrons.

(1)
 
(ii)	Draw the shape you would expect for the phosphine molecule, suggesting a value for the HPH bond angle.

HPH bond angle .......................................................................................................
(2)
 
(iii)	Explain the shape of the phosphine molecule you have given in your answer in (ii).
	Justify your value for the HPH bond angle.
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(2)
 
(b)	(i)	Write a balanced equation, including state symbols, for the atomisation of phosphine gas.
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(1)

(ii)	Use your answer to (i) and the data below to calculate the standard enthalpy change of atomisation of phosphine at 298 K. Include a sign and units in your answer.
ΔHοf[PH3(g)]	=	+	5.4 kJ mol-1
ΔHοat[½H2(g)]	=	+	218.0 kJ mol-1
ΔHοat[P(s)]	=	+	314.6 kJ mol-1

(3)
 
(iii)	Calculate a value for the bond energy of the bond between phosphorus and hydrogen, using your answer to (ii).

(1)
(Total 10 marks)

12.	(a)	Draw diagrams to show how the following bonds are formed from atomic orbitals.
s bond

p bond

(2)
 
(b)	(i)	State the shape of a methane, CH4, molecule, and explain why it has this shape.
Shape: ...................................................................................................................
Explanation: ..........................................................................................................
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(3)
(ii)	State the shape of a carbon dioxide, CO2, molecule, and explain why it has this shape.
Shape: ...................................................................................................................
Explanation: ..........................................................................................................
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(2)
(Total 7 marks)

13.	Silicon reacts with chlorine to produce silicon tetrachloride, as shown in the following equation
Si(s) + 2Cl2(g) → SiCl4(l)
(a)	(i)	Calculate the mass of silicon tetrachloride obtained from 10.0 g of silicon.

(3)
 
(ii)	Calculate the minimum volume of chlorine that would be required to react completely with 10.0 g of silicon.
	[1 mol of gas occupies 24.0 dm3 under the conditions of the experiment]

(2)

(b)	Draw a silicon tetrachloride molecule, SiCl4, showing its three-dimensional shape.
Name the shape and state the bond angle. Explain why the molecule has this shape.
	Diagram

	Name of shape .............................................................................................................
	Bond angle ..............................................
	Explanation of shape
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(5)
 
(c)	(i)	Why are silicon-chlorine bonds polar?
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(1)

(ii)	Explain why the silicon tetrachloride molecule has no permanent dipole.
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(2)
(Total 13 marks)

14.	(a)	Draw the ammonia molecule, NH3, making its three-dimensional shape clear. Mark in the bond angle on your diagram. Explain why ammonia has this shape and this bond angle.
	Diagram

	Explanation
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(4)

(b)	Explain whether ammonia is a polar molecule or not.
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(2)
 
(c)	Explain, in terms of the intermolecular forces in both compounds, why ammonia has a higher boiling temperature than phosphine, PH3.
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(3)
 
(d)	(i)	Explain, in terms of electrons, how ammonia can react with hydrogen ions to form ammonium ions, NH4+.
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(2)

(ii)	State the number of protons and the number of electrons present in an ammonium ion.
	number of protons .....................................
	number of electrons....................................
(2)
(Total 13 marks)

15.	(a)	(i)	Explain why a water molecule does not have a linear shape.
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(2)
 
(ii)	State the HOH bond angle in water and explain why it has this value.
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(2)

(b)	(i)	Draw the boron trichloride molecule, BCl3, making its shape clear. Mark in the bond angle on your diagram.

(2)
 
(ii)	Explain why a B–Cl bond is polar.
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(1)
 
(iii)	Explain why a BCl3 molecule is non-polar.
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(1)
 
(iv)	Name the strongest intermolecular force between boron trichloride molecules.
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(1)
 
(c)	A compound of phosphorus and chlorine has the composition by mass shown below.
Element	% by mass	
P	14.9	
Cl	85.1	
	Calculate the empirical formula of this compound.

(2)
(Total 11 marks)

16.	The Hess cycle below can be used to estimate the enthalpy change of formation, DHf, of the unstable gaseous compound with the formula HOCl(g).

(a)	(i)	Insert formulae, with state symbols, into the appropriate boxes, to show the correct quantities of each element.
(1)

(ii)	Use the cycle to calculate a value for the enthalpy change of formation, [HOCl(g)].

(1)
 
(iii)	Assuming that the H—O bond energy is +464 kJ mol–1, calculate a value for the O—Cl bond energy.

(1)

(b)	(i)	Draw a ‘dot and cross’ diagram for the HOCl molecule showing outer electrons only.

(2)
(ii)	Predict the HOCl bond angle. Justify your answer.
Angle ................................................................................................................
Justification ......................................................................................................
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(2)

(c)	HOCl(g) can be made from chlorine(I) oxide by the reversible reaction
Cl2O(g) + H2O(g)  2HOCl(g)
	What effect, if any, would an increase in pressure have on the proportion of HOCl(g) at equilibrium? Justify your answer.
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(2)
(Total 9 marks)

17.	(a)	(i)	A diagram of the structure of solid sodium chloride is shown below.
	Label the diagram to identify the particles present in solid sodium chloride.
	
(1)

(ii)	Explain why sodium chloride has a high melting temperature.
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(2)
 
(b)	A diagram of the structure of solid graphite is shown below.
	On the diagram name and label the types of bonding that exist in solid graphite.
	
(2)

(c)	A diagram of the structure of solid diamond is shown below.
	On the diagram name and label the type of bond that exists in solid diamond.
	
(1)
 
(d)	The densities of diamond and graphite are
	Density / g cm–3	
Diamond	3.53	
Graphite	2.25	
	Suggest, using information from (b) and (c), why diamond is more dense than graphite.
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(2)
(Total 8 marks)

18.	Silicon, phosphorus and sulphur form chlorides with molecular formulae SiCl4, PCl3, SCl2.
	Draw the shapes you would expect for these molecules, suggesting a value for the bond angle in each case.
	SiCl4

	ClSiCl bond angle ...............
	PCl3

	ClPCl bond angle ...............
	SCl2

	ClSCl bond angle ...............
(Total 3 marks)

19.	Phosphorus reacts with a limited amount of chlorine to produce phosphorus trichloride, PCl3.
(i)	Draw a dot and cross diagram to show the arrangement of the electrons in phosphorus trichloride, PCl3. You need only show the outer shell electrons.

(2)
 
(ii)	Draw the phosphorus trichloride molecule, making its three-dimensional shape clear.

(1)

(iii)	Explain
•	the shape of the phosphorus trichloride molecule.
•	why the Cl¾P¾Cl bond angle is different from the H¾C¾H bond angle in methane, CH4.
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(3)
(Total 6 marks)

20.	Which of the following best describes the molecular shape of carbon dioxide, CO2?
A	linear
B	trigonal planar
C	triangular
D	v-shaped
(Total 1 mark)

21.	(a)	(i)	Name the type of bonding that exists between water molecules.
...........................................................................................................................
(1)
 
(ii)	Draw a diagram to show this bonding. Use displayed formulae of two water molecules. Clearly mark and label the bond angle between the water molecules.

(2)
 
(b)	(i)	Draw the boron trichloride molecule, BCl3, making its shape clear. Mark the bond angle on your diagram.

(2)
 
(ii)	Explain why boron trichloride has this shape.
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(3)
 
(iii)	Explain why a B–Cl bond is polar.
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(1)

(iv)	Explain why a BCl3 molecule is non-polar.
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(1)
 
(v)	Name the strongest intermolecular force between boron trichloride molecules.
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(1)
(Total 11 marks)

22.	Two compounds may be similar in that they both have
A	dative covalent bonds in their molecules
B	at least one bond angle of 120° in each molecule
C	non-polar molecules
D	linear molecules
 
	Select from A–D, the similarity between each of the compounds below.
(a)	Benzene, C6H6 and cyclohexane, C6H12
A
B
C
D
(1)

(b)	Hydrogen cyanide, HCN, and carbon dioxide, CO2
A
B
C
D
(1)
(Total 2 marks)