1. What is the formula for the compound formed by calcium and nitrogen?

A. CaN B. Ca2N C. Ca2N3 D. Ca3N2

2. Element X is in group 2, and element Y in group 7, of the periodic table. Which ions will be present in the
compound formed when X and Y react together?

+ – 2+ – + 2– 2– +
A. X and Y B. X and Y C. X and Y D. X and Y

3. What happens when sodium and oxygen combine together?

A. Each sodium atom gains one electron. B. Each sodium atom loses one electron.

C. Each oxygen atom gains one electron. D.Each oxygen atom loses one electron.

4. Which statement is true for most ionic compounds?

A. They contain elements of similar electronegativity. B. They conduct electricity in the solid state.

C. They are coloured. D. They have high melting and boiling points.

5. Which fluoride is the most ionic?

A. NaF B. CsF C. MgF2 D. BaF2

6. What type of solid materials are typically hard, have high melting points and poor electrical conductivities?

I. Ionic II. Metallic III. Covalent-network

A. I and II only B. I and III only C. II and III only D. I, II and III

7. A substance has the following properties:

What is the most probable structure of this substance?

A.     Network covalent
B.     Polar covalent molecule
C.     Ionic lattice
D.     Metallic lattice

8. Which compound contains both ionic and covalent bonds?

A.  SIH4
B. NaNO3
C. H2CO
D. Na2S
 –3
9. Which substance is most soluble in water (in mol dm ) at 298 K?

A. CH3CH3 B. CH3OCH3

C. CH3CH2OH D. CH3CH2CH2CH2OH

10. When the following bond types are listed in decreasing order of strength (strongest first), what is the correct
order?

A. covalent  hydrogen  van der Waals’

B. covalent  van der Waals’  hydrogen

C. hydrogen  covalent  van der Waals’

D. van der Waals’  hydrogen  covalent

11. The diagrams below represent the structures of iodine, sodium and sodium iodide.

A B C

(a) (i) Identify which of the structures (A, B and C) correspond to iodine, sodium and sodium iodide.

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….
(1)

(ii) State the type of bonding in each structure.

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….
(1)
 (b) (i) Sodium and sodium iodide can both conduct electricity when molten, but only sodium can
conduct electricity when solid. Explain this difference in conductivity in terms of the structures
of sodium and sodium iodide.

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….
(3)

(ii) Explain the high volatility of iodine compared to sodium and sodium iodide.

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….

……………………………………………………………………………………….
(2)
(Total 7 marks)

12. Arrange the following in decreasing order of bond angle (largest one first), and explain your reasoning.

– +
NH2 , NH3, NH4
(Total 3 marks)
13. (a) An important compound of nitrogen is ammonia, NH3. The chemistry of ammonia is influenced by its
polarity and its ability to form hydrogen bonds. Polarity can be explained in terms of electronegativity.
(i) Explain the term electronegativity.

……………………………………………………………………………………

……………………………………………………………………………………
(1)
(ii) Draw a diagram to show hydrogen bonding between two molecules of NH 3.
The diagram should include any dipoles and/or lone pairs of electrons

(2)
(iii) State the H–N–H bond angle in an ammonia molecule.

………………………………………………………………………………………
(1)
(iv) Explain why the ammonia molecule is polar.

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………
(1)

+
(b) Ammonia reacts with hydrogen ions forming ammonium ions, NH 4 .

(i) State the H–N–H bond angle in an ammonium ion.

……………………………………………………………………………………
(1)

+
(ii) Explain why the H–N–H bond angle of NH3 is different from the H–N–H bond angle of NH4 ;
referring to both species in your answer.

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………

……………………………………………………………………………………
(2)
(Total 11 marks)
14.(a) Draw the Lewis structure of methanoic acid, HCOOH.

(1)

(b) In methanoic acid, predict the bond angle around the

(2)

(i) carbon atom. .....................................................................................................

(ii) oxygen atom bonded to the hydrogen atom. ...................................................

(c) State and explain the relationship between the length and strength of the bonds between the carbon
atom and the two oxygen atoms in methanoic acid.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
DBBDB BABCA

11. (a) (i) A – sodium iodide, B – sodium, C – iodine (three correct [1]); 1
Accept correct formulas.
(ii) A – ionic bonding;
B – metallic bonding;
C – van der Waals’ forces (and covalent bonding); 3
(b) (i) (for Na) (lattice of) positive ions/atoms;
delocalized/free electrons/sea of electrons;
(for NaI) oppositely charged ions/positive and negative ions;
free to move (only) in molten state; 4
(ii) forces between I2 molecules are weak;
ionic/metallic bonding strong(er); 2
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12.

+ –
NH4 > NH3 > NH2 ;
+
NH4 has four bonded electron pairs (and no lone electron pairs);
NH3 has three bonded electron pairs and one electron lone pair;
–
NH2 has two bonded electron pairs and two electron lone pairs;
Accept correct Lewis structures with lone electron pairs clearly shown.

lone pair-lone pair > lone pair-bonded pair > bonded pair-bonded pair/
lone pairs of electrons repel more than bonding pairs of electrons/OWTTE; 5
Do not accept repulsion between atoms.

13. (a) (i) (relative) measure of an atom’s attraction for electrons; in a bond; 2
(ii)
– +
xx
N H h y d ro g e n b o n d in g

+
+ H H

xx
– +
N H

+
+ H H
Suitable diagram indicating
dipoles;
lone pairs of electrons;
hydrogen bonding; 3
(iii) 107°; 1
Accept answer in range 107 to 109° .
(iv) molecule is asymmetrical/OWTTE; 1
 (b) (i) 109.5°; 1
+
(ii) NH4 has four bonding pairs
(around central atom so is a regular tetrahedron);
NH3 has three bonding pairs (of electrons) and one non-bonding pair;
non-bonding pairs (of electrons) exert a greater repulsive force; 3
Accept suitable diagrams.

14.(a)

H C

O H 1
No mark without lone electron pairs.
Correct shape not necessary.
Do not award mark if dots/crosses and bond lines are shown.
Accept lone pairs represented as straight lines.
(b) O − C − O = 120°/H − C − O = 120°;
C − O − H = 109°/<109°; 2
No mark for 109.5°
Accept answer in range 100–109°

(c) length: C = O < C − O;

strength: C = O > C – O;
greater number of electrons between nuclei pull atoms together and require greater energy to break;
Or
double bonds are shorter/single bonds are longer;
double bonds are stronger/single bonds are weaker; 3
Accept stronger attraction between nuclei and (bonding) electrons.
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