PRACTICE EXAMINATION QUESTIONS FOR 1.

1 ATOMIC STRUCTURE
(includes some questions from 1.4 Periodicity)

1. At room temperature, both sodium metal and sodium chloride are crystalline solids which contain
ions.

(a) On the diagrams for sodium metal and sodium chloride below, mark the charge for
each ion.

Sodium metal Sodium chloride

(2)

(b) (i) Explain how the ions are held together in solid sodium metal.
positively charged ions are attrached to the sea of delocalized

...........................................................................................................................
electrons

Attraction /electrostatic forces/bonds/attractions between (positive)

ions/lattice and delocalised/free electrons/sea of electrons.
...........................................................................................................................

(ii) Explain how the ions are held together in solid sodium chloride.
oppositely charged ions are attracted to eachother
...........................................................................................................................
Electrostatic attractions/forces between ions or attractions between
(oppositely charged) ions/ Na+ & Cl
...........................................................................................................................

(iii) The melting point of sodium chloride is much higher than that of sodium metal.
What can be deduced from this information?
stronger electrostatic forces or ionic bonds meaning it requires '
...........................................................................................................................
more energy to break them apart
...........................................................................................................................
(Here) the ionic bonding in NaCl is stronger/requires more energy to (3)
break than the metallic bonding in Na
(c) Compare the electrical conductivity of solid sodium metal with that of solid sodium
chloride. Explain your answer.
solid sodium chloride will have more free ions to move around

Comparison ................................................................................................................
and conduct electricity while solid sodium metal

Sodium conducts and sodium chloride does NOT conduct

.....................................................................................................................................
(Delocalised) electrons flow though the metal
Explanation ................................................................................................................
Ions can’t move in solid salt
.....................................................................................................................................

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

Mill Hill High School 1

 (d) Explain why sodium metal is malleable (can be hammered into shape).
all atoms are the same shape and can slide over eachother due to the uniform
.....................................................................................................................................
structure
.....................................................................................................................................
Layers can slide over each other (1)
(Total 9 marks)

2. The equation below shows the reaction between boron trifluoride and a fluoride ion.

BF3 + F– → BF 4–

dont allow shapes(i) Draw diagrams to show the shape of the BF3 molecule and the shape of the BF 4– ion. In
with lone pairs
each case, name the shape. Account for the shape of the BF 4– ion and state the bond angle
Trigonal planar/ present.
planar triangulartriangular
pryamidal tetrahedral

(ii) In terms of the electrons involved, explain how the bond between the BF3 molecule and the
F– ion is formed. Name the type of bond formed in this reaction.
(Total 9 marks)

3. Draw the shape of a molecule of BeCl2 and the shape of a molecule of Cl2O. Show any lone
pairs of electrons on the central atom. Name the shape of each molecule.

BeCl2 Cl2O

Name of shape ......................................... Name of shape .........................................

(4)
(Total 4 marks)

Mill Hill High School 2

4. Ammonia, NH3, reacts with sodium to form sodium amide, NaNH2, and hydrogen.

−
(a) Draw the shape of an ammonia molecule and that of an amide ion, NH 2

In each case show any lone pairs of electrons.

−
NH3 NH 2

(b) State the bond angle found in an ammonia molecule.

........................................................................................…...............................

(c) Explain why the bond angle in an amide ion is smaller than that in an ammonia
molecule.
has 2 lone pairs which repel more strongly than one lone pair,
........................................................................................…...............................
reducing the angle even further
........................................................................................…...............................
More lone pairs on NH2–, than on NH3
........................................................................................…...............................

........................................................................................…...............................
(5)
(Total 5 marks)

Mill Hill High School 3

5.

(a) Describe the bonding that is present in metals.

ionic bonding between two elements/atoms/ the sharing of electrons
...........................................................................................................................
between metal atoms/elements
...........................................................................................................................
(electrostatic forces of) attraction / held together by
interactions between (1)
...........................................................................................................................
positive ions / cations / nuclei not just metal ions (1)
and delocalised or free (outer shell) electrons / ‘sea’ of
electrons /
...........................................................................................................................
cloud of electrons (1)
(3)

(b) Explain how the bonding and structure lead to the typical metallic properties of
electrical conductivity and malleability.
conductivity clear indication that electrons are mobile / can move (1)
Electrical conductivity .....................................................................................
electrons / carry charge / care charge carriers / move in same
direction not ‘so current can flow’
ionic bonds and electrostatic forces of attraction

between positive metal ions and sea of delocalised electrons

...........................................................................................................................
result metal to have low electrical conducitivty

...........................................................................................................................
malleable due to the fact that ions/atoms/particles can slide
Malleability.......................................................................................................
over eachother and are in a uniform structure
...........................................................................................................................
cations / positive ions / atoms in the lattice are
all identical / the same size / (planes of) ions (atoms) can slide
...........................................................................................................................
easily over one another (1)
attractive forces in the lattice are the same whichever ions
(atoms) are adjacent / attractive forces remain the same throughout (4)
the lattice (1)

(c) Suggest a reason why aluminium is a better conductor of electricity than magnesium.
has a higher mp/bp which means that its safer
...........................................................................................................................
more electrons delocalised / more outer shell electrons (1)
...........................................................................................................................
in aluminium compared with magnesium / reference to
Al3+ and Mg2+ (1)
...........................................................................................................................
(2)
(Total 9 marks)

6. The table below shows the electronegativity values of some elements.

Fluorine Chlorine Bromine Iodine Carbon Hydrogen

Electronegativity 4.0 3.0 2.8 2.5 2.5 2.1

(a) Define the term electronegativity.

the ability of an atom to attract a pair of electrons in a covalent bond towards
.....................................................................................................................................
itself
.....................................................................................................................................
tendency / strength / ability / power of an atom / element / nucleus to attract /
pull / withdraw electrons / e - density / bonding pair / shared pair 1
.....................................................................................................................................
in a covalent bond
(2)

Mill Hill High School 4

 (b) The table below shows the boiling points of fluorine, fluoromethane (CH3F ) and hydrogen
fluoride.

F–F F H–F

C
H H
H

Boiling point/K 85 194 293

(i) Name the strongest type of intermolecular force present in:

van der waals
Liquid F2 .........................................................................................................
hydrogen bonding dipole-dipole (not just ‘dipole’)
Liquid CH3F ...................................................................................................
dipole dipole bonding hydrogen bonding
Liquid HF .......................................................................................................

(ii) Explain how the strongest type of intermolecular force in liquid HF arises.
theres a big/huge difference in electronegativity between the elements
...........................................................................................................................
H and F which causes permanent dipoles to be created as the

electrons are attracted towards fluorine more

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

+H-F- dipole created or dipole clearly implied

...........................................................................................................................
attraction/bond formed between +H and lone pair on F
...........................................................................................................................
(6)

(c) The table below shows the boiling points of some other hydrogen halides.
HCl HBr HI
Boiling point / K 188 206 238

(i) Explain the trend in the boiling points of the hydrogen halides from HCl to HI.
as we go down group 7 the bp decreases due to the atomic radius

...........................................................................................................................
increasing and shielding effect increases so its harder to gain an

electron and and electrostatic forces of attractio between outer electron and nucleus
become weaker so less energy needed to break apart the forces and bonds
...........................................................................................................................
van der Waals’ / induced/temporary dipole-dipole / dispersion /
...........................................................................................................................
London forces / attractions (ignore references to dipole-dipole) 1
increase with the increasing M2 / size / mass / N1 of e– / size

(ii) Give one reason why the boiling point of HF is higher than that of all the other
hydrogen halides.
requires less energy to break apart bonds and forces
...........................................................................................................................
hydrogen bonding stronger than van der Waals’ attraction/forces
...........................................................................................................................
(3)
(Total 11 marks)

Mill Hill High School 5

7. (a) Methanol has the structure

H C O H

Explain why the O–H bond in a methanol molecule is polar.

huge difference in electronegativity between H and O creating dipole
.....................................................................................................................................
dipole forces
.....................................................................................................................................

Oxygen more/very/highly electronegative (than hydrogen)

.....................................................................................................................................
(2)

(b) The boiling point of methanol is +65 °C; the boiling point of oxygen is –183 °C. Methanol
and oxygen each have an Mr value of 32. Explain, in terms of the intermolecular forces
present in each case, why the boiling point of methanol is much higher than that of oxygen.
van der Waals’ forces between oxygen molecules;
Hydrogen bonding between methanol molecules;
.....................................................................................................................................
H-B stronger than van der Waals’ OR stronger IMF in methanol;
.....................................................................................................................................

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

.....................................................................................................................................
(3)
(Total 5 marks)

Mill Hill High School 6

8. (a) The diagram below shows the melting points of some of the elements in Period 3.

2000

1600

1200
Melting
point/K
800

400

0
Na Mg Al Si P S Cl Ar

(i) On the diagram, use crosses to mark the approximate positions of the melting points
for the elements silicon, chlorine and argon. Complete the diagram by joining the
crosses.

(ii) By referring to its structure and bonding, explain your choice of position for the
melting point of silicon.
Si is macromolecular/giant molecular/giant covalent/ giant atomic
Covalent bonds need to be broken/accept ‘overcome’
...........................................................................................................................
Covalent bonds are strong / many covalent bonds involved/requires
...........................................................................................................................
much energy/hard to break
...........................................................................................................................

(iii) Explain why the melting point of sulphur, S8, is higher than that of phosphorus, P4
have more electrons and therefore stronger VdW forces so more electrostatic

...........................................................................................................................
forces of attraction
Intermolecular force = van der Waals’/induced
dipole–dipole/dispersion forces 1
...........................................................................................................................
QoL Sulphur has greater Mr / size / surface area/more electrons/more
atoms so stronger intermolecular forces (comparison) (8)

(b) State and explain the trend in melting point of the Group II elements Ca–Ba.
Decreases
Trend ...........................................................................................................................
Increase in size of ion/atom / more shells / decrease in charge density /
Explanation ..................................................................................................................
decrease in charge size ratio 1
Weaker attraction for delocalised/free/sea of electrons / weaker
metallic bonding
.....................................................................................................................................

.....................................................................................................................................
(3)
(Total 11 marks)

Mill Hill High School 7

9. State and explain the trend in the melting points of the Period 3 metals Na, Mg and Al.
increases going across
Trend ...........................................................................................................................
Al has a higher charge density and therefore more electrons
Explanation ...............................................................................................................
more protons / higher charge on cation / more delocalised e– / smaller
atomic/ionic radius;
......................................................................................................................................
stronger attraction between (cat)ions and delocalised/free/mobile e–
stronger metallic bonding;
......................................................................................................................................
(3)
(Total 3 marks)

10. (a) (i) Describe the bonding in a metal.

electrostatic forces of attractio between positively charged
......................................................................................................................
ions and delocalised electrons
......................................................................................................................
positive ions (1)
......................................................................................................................
(attract) delocalised electrons (1) (or sea of or free or mobile) (1)

(ii) Explain why magnesium has a higher melting point than sodium.
has a greater charge density so stronger electrostatic forces of
......................................................................................................................
attraction meaning will need more energy to break the bonds
......................................................................................................................
more protons (1) (or Mg2+ more charge than Na+)
attracts delocalised (or bonding) electrons more strongly (1)
......................................................................................................................
(4)

(b) Why do diamond and graphite both have high melting points?
have strong covalent bonds between 4 carbon atoms and so
..............................................................................................................................
alot of energy is needed to break these strong covalent bonds
..............................................................................................................................
macromolecular (1) (or giant molecule etc)
..............................................................................................................................
covalent (1)
strong covalent bonds (1)

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

(c) Why is graphite a good conductor of electricity?

one carbon isnt bonded so theres a free electron which is free to move
..............................................................................................................................
around and conduct electricity
delocalised (OR free or sea of or mobile) electrons (1)
(1)

(d) Why is graphite soft?

layers can slide over eachother due to the fact that its 3 carbons
..............................................................................................................................
bonded to eachother instead of 4 meaning theres a free carbon/electron
..............................................................................................................................
Planes (1)
..............................................................................................................................
weak (bonds) forces between planes (1)
(2)
or vdw forces between planes
(Total 10 marks)

Mill Hill High School 8

11. Sodium sulphide, Na2S, is a high melting point solid which conducts electricity when
molten. Carbon disulphide, CS2, is a liquid which does not conduct electricity.

(a) Deduce the type of bonding present in Na2S and that present in CS2
ionic bonding
Bonding in Na2S ........................................................................................
covalent bonding
Bonding in CS2...........................................................................................

(b) By reference to all the atoms involved explain, in terms of electrons, how Na2S is
formed from its atoms.
Clear indication of electron transfer from Na to S (1)
...................................................................................................................
1 e– from each (of 2) Na atoms or 2 e– from 2 Na atoms (1)
...................................................................................................................

(c) Draw a diagram, including all the outer electrons, to represent the bonding present in
CS2

(6)
(Total 6 narks)

12. (a) The diagram below represents a part of the structure of sodium chloride. The ionic charge
is shown on the centre of only one of the ions.

(i) On the diagram, mark the charges on the four negative ions.

(ii) What change occurs to the motion of the ions in sodium chloride when it is heated
from room temperature to a temperature below its melting point?
vibrate faster (1)
....................................................................................................................
(2)

Mill Hill High School 9

 (b) Sodium chloride can be formed by reacting sodium with chlorine.

(ii) A chloride ion has one more electron than a chlorine atom. In the formation of
sodium chloride, from where does this electron come?
sodium
....................................................................................................................

(ii) What property of the atoms joined by a covalent bond causes the bond to be polar?
difference in electronegativity
....................................................................................................................
(2)
(Total 4 marks)

13. Phosphorus and nitrogen are in Group V of the Periodic Table and both elements form hydrides.
Phosphine, PH3, reacts to form phosphonium ions, PH +4 , in a similar way to that by which
ammonia, NH3, forms ammonium ions, NH +4

(a) Give the name of the type of bond formed when phosphine reacts with an H+ ion. Explain
how this bond is formed.
hydrogen bonding dative / coordinate (covalent) bond;
Type of bond .............................................................................................................
Lone/non-bonding pair / both electrons;
Explanation .............................................................................................................
(donated) from P to H+;

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

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

(b) Draw the shapes, including any lone pairs of electrons, of a phosphine molecule and of a
phosphonium ion.
Give the name of the shape of the phosphine molecule and state the bond angle found in the
phosphonium ion.

PH3 PH +4

square planar
triangular pyramidal 120
107

Shape of PH3 ……………………… Bond angle in PH 4+ ……………......

(4)
(Total 7 marks)

Mill Hill High School 10

14. (a) State the meaning of the term electronegativity.
Ability (or power) of an atom to attract electron density
the ability for an atom to attract a pair of electrons towards itself (or electrons or -ve charge) (1)
...............................................................................................................................
in a covalent bond (1)
in a covalent bond
...............................................................................................................................
(2)

(b) State and explain the trend in electronegativity values across Period 3 from sodium to
chlorine.
electronegativity increases
Trend......................................................................................................................
atomic radius stays the same
Explanation............................................................................................................
nuclear charge (number of protons) increases (1)
electrons in same shell (1)
...............................................................................................................................
(3)
(Total 5 marks)

15. (a) The shape of the molecule BCl3 and that of the unstable molecule CCl2 are shown below.

Cl
B C
Cl Cl Cl Cl

(i) Why is each bond angle exactly 120° in BCl3?

doesnt have any lone pairs
.....................................................................................................................
3 (bonding) pairs of electrons (1) repel equally (1)

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

(ii) Predict the bond angle in CCl2 and explain why this angle is different from that in
BCl3

Predicted bond angle ...................................................................................

has one lone pair that repels and is stronger than bonding pairs
Explanation ..................................................................................................
: lone pair (1)
......................................................................................................................
repels more than bonding pair (1)
(5)

(b) Give the name which describes the shape of molecules having bond angles of 109° 28'.
Give an example of one such molecule.
Tetrahedral (1)
Name of shape ........................................................................................................
CH4 etc
Example...................................................................................................................
(2)

Mill Hill High School 11

 (c) The shape of the XeF4 molecule is shown below.

F F
Xe
F F

(i) State the bond angle in XeF4

90
.......................................................................................................................

(ii) Suggest why the lone pairs of electrons are opposite each other in this molecule.
they repel eachother hence why theyre as far away as possible

.......................................................................................................................
from eachother

lone pairs (or they) repel more than bonding pairs (or most) (1)
(so are) as far apart as possible (1)
.......................................................................................................................

(iii) Name the shape of this molecule, given that the shape describes the positions of the
Xe and F atoms only.
square planar
.......................................................................................................................
(4)

(d) Draw a sketch of the NF3 molecule. Indicate in your sketch any lone pairs of electrons on
nitrogen.

(2)
(Total 13 marks)

16. (a) Describe the motion of the particles in solid iodine and in iodine vapour.
particles are stationary and not free to move as they are joined to eachother
Motion in solid iodine..................................................................................................
vibration (1)
about a fixed print (1)

.....................................................................................................................................
fast movement in all and random directions as they have lots of energy
Motion in iodine vapour..............................................................................................
random (1)
(or free to move)
.....................................................................................................................................
(3)

(b) Explain why solid iodine vaporises when warmed gently.

low boiling point
.....................................................................................................................................
{weak intermolecular forces (1)
or v.d.w forces
.....................................................................................................................................
easily broken (1)
or requires little energy to break
.....................................................................................................................................
(2)

Mill Hill High School 12

 (c) Silver and sodium chloride melt at similar temperatures. Give two physical properties of
silver which are different from those of sodium chloride and, in each case, give one reason
why the property of silver is different from that of sodium chloride.
conducts electricity (1)
First property of silver................................................................................................
delocalised electrons (1)
Reason for difference..................................................................................................

.....................................................................................................................................
malleable (1)
Second property of silver............................................................................................
planes of atoms slide (1)
Reason for difference..................................................................................................

.....................................................................................................................................
(4)

(d) Draw the shapes of BeCl2, NCl3 and BeCl 2 –4 . In each case, show any lone-pair electrons on
the central atom and state the value of the bond angle.

BeCl2 NCl3 BeCl 2 –4

(6)
(Total 15 marks)

17. Silicon dioxide has a macromolecular structure. Draw a diagram to show the arrangement
of atoms around a silicon atom in silicon dioxide. Give the name of the shape of this
arrangement of atoms and state the bond angle.

Diagram
diagram showing a tetrahedral arrangement of four oxygen atoms around a
central silicon atom (must include attempt at a 3-d representation) (1)

Name of shape ............................................................................................................

tetrahedral (1)

109.5° / 109° / 110° (1)

Bond angle ..................................................................................................................
(3)
(Total 3 marks)

Mill Hill High School 13

18. (a) When considering electron pair repulsions in molecules, why does a lone pair of electrons
repel more strongly than a bonding pair?
both negatively charged more compact (1)
.....................................................................................................................................
(1)

(b) The diagram below shows a hydrogen peroxide molecule.

O O

(i) On the diagram above, draw the lone pairs, in appropriate positions, on the oxygen
atoms.

(ii) Indicate, on the diagram, the magnitude of one of the bond angles.

(iii) Name the strongest type of intermolecular force which exists between molecules of
hydrogen peroxide in the pure liquid.
hydrogen bonding
...........................................................................................................................
(4)

(c) Draw a diagram to illustrate the shape of a molecule of SF4 and predict the bond angle(s).

Diagram of shape

Bond angle(s)..............................................................................................................
(4)

(d) Name two types of intermolecular force which exist between molecules in liquid SF4
van der waals force
Type I...........................................................................................................................
dipole dipole
Type2............................................................................................................................
(2)
(Total 11 marks)

19. (a) Name the type of force that holds the particles together in an ionic crystal.
electrostatic forces of attraction
.....................................................................................................................................
(1)

(b) What is a covalent bond?

the sharing of electron between two elements
.....................................................................................................................................
(1)

Mill Hill High School 14

 (c) State how a co-ordinate bond is formed.
a covalent bond between an atom and an element where one {both electrons, electron pair (1)
element shares a pair of electrons but doesnt recieve any (donated) from {one, the same atom {or molecule, or species (1)
.....................................................................................................................................

.....................................................................................................................................
(2)

(d) Describe the bonding in a metal.

electrostatic forces of attraction between positively charged ions and a sea of electrons
.....................................................................................................................................
(positive) ions (or atoms) (1)
.....................................................................................................................................
delocalised electron (1) (or sea of, or mobile, or free)

.....................................................................................................................................
(2)

(e) A molecule of hydrogen chloride has a dipole and molecules of hydrogen chloride attract
each other by permanent dipole-dipole forces. Molecules ot chlorine are non-polar.

(i) What is a permanent dipole?

when theres a permanent polarity due to big difference in electronegativity between elements
...........................................................................................................................
Charge separation (or unequal sharing of electrons) (1)
leading to
...........................................................................................................................

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

(ii) Explain why a molecule of hydrogen chloride is polar.

chlorine more electronegative then H (1)
...........................................................................................................................
attracts electrons towards C1 (1)
...........................................................................................................................

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

(iii) Name the type of force which exists between molecules of chlorine.
covalent bond van der Waals’ (1)
...........................................................................................................................
(5)

(f) Show, by means of a diagram, how two molecules of hydrogen fluoride are attracted to
each other by hydrogen bonding; include all lone-pair electrons and partial charges in your
diagram.

(3)

(g) Why is there no hydrogen bonding between molecules of hydrogen bromide?

bromine not sufficiently electronegative (1)
.....................................................................................................................................

.....................................................................................................................................
(1)
(Total 15 marks)

Mill Hill High School 15

20. The table below gives the boiling points, Tb, of some hydrogen halides.

Hydrogen halide HF HCl HBr HI

Tb /K 293 188 206 238

(a) By referring to the types of intermolecular force involved, explain why energy must be
supplied in order to boil liquid hydrogen chloride.
in order to break apart the forces which are holding the molecules together
....................................................................................................................................
van der Waals’ (1)
dipole - dipole (1)
....................................................................................................................................
energy needed to overcome (intermolecular or vdw or dipole-dipole) forces (1)
....................................................................................................................................

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

(b) Explain why the boiling point of hydrogen bromide lies between those of hydrogen
chloride and hydrogen iodide.
because bromide has a higher bp than chlorine and a lower bp than iodide
....................................................................................................................................
HBr is intermediate in size (or polarisibility) (1)
....................................................................................................................................
van der Waals’ forces depend on molecular size (1)

....................................................................................................................................
(2)

(c) Explain why the boiling point of hydrogen fluoride is higher than that of hydrogen
chloride.
fluoride is more electronegative than chloride
....................................................................................................................................
hydrogen bonding in HF (1)
stronger than intermolecular forces in HC1 (1)
....................................................................................................................................
(or strongest intermolecular force)
....................................................................................................................................
(2)

(d) Draw a sketch to illustrate how two molecules of hydrogen fluoride interact in liquid
hydrogen fluoride.
lone pair

(2)
(Total 9 marks)

Mill Hill High School 16

21. Sulphur will combine separately with carbon, hydrogen and sodium to form carbon
disulphide (CS2), hydrogen sulphide (H2S) and sodium sulphide (Na2S) respectively. The
bonding in these compounds is similar to that in CO2, H2O and Na2O .

(a) Complete the table in Figure 2 by classifying the compounds as either ionic or
covalent.

Melting point/K Ionic or covalent

covalent
Carbon disulphide 162

covalent
Hydrogen sulphide 187

Sodium sulphide 1450 ionic

Figure 2
(3)

(b) One of the compounds in Figure 2 shows high electrical conductivity under
appropriate conditions. Identify the compound, by name or formula, and state one
condition under which it shows high electrical conductivity.
carbon disulphide
sodium sulphide / Na2S (1)
Name or formula of compound ........................................................................

Condition ..........................................................................................................
liquid / molten / aqueous solution (independent of first mark) (1)
(2)
(Total 5 marks)

22. (a) State what is meant by the term polar bond.

partial charges on atoms of bond / centres of positive and negative charges do
not coincide / bonding pair shared unequally (1)
.....................................................................................................................................

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

(b) Sulphuric acid is a liquid that can be represented by the formula drawn below.

O O H
S
O O H

Given that the electronegativity values for hydrogen, sulphur and oxygen are 2.1, 2.5 and
3.5 respectively, clearly indicate the polarity of each bond present in the formula given.
(2)

Mill Hill High School 17

 (c) Suggest the strongest type of intermolecular force present in pure sulphuric acid.

Briefly explain how this type of intermolecular force arises.

van der waals and this is due to the increaing number of electrons
.....................................................................................................................................
hydrogen bonding (1)
.....................................................................................................................................
attraction between (+ of) H atoms and (– of) O atoms in adjacent or
different molecules (H of one molecule, O of another) (1)

.....................................................................................................................................
(2)
(Total 5 marks)

23. (a) Sketch the shapes of each of the following molecules, showing any lone pairs of electrons.
In each case, state the bond angle(s) present in the molecule and name the shape.

Molecule Sketch of shape Bond angle(s) Name of shape

trigonal planar

BF3

107 triangular pyramidal

NF3

Trigonal bipyramid
87º to 90º or
and/or trigonal planar
ClF3 118º to 120º

(9)

(b) State the types of intermolecular force which exist, in the liquid state, between pairs of BF3
molecules and between pairs of NF3 molecules.
van der waal
BF3 ..............................................................................................................................
dipole dipole van der Waals’ (1) dipole-dipole (1)
NF3 ..............................................................................................................................
(3)

Mill Hill High School 18

 (c) Name the type of bond which you would expect to be formed between a molecule of BF3
and a molecule of NF3. Explain how this bond is able to form.
co-ordinate (1)
Name of bond ............................................................................................................
lone pair on N (1)
Explanation ...............................................................................................................
donated (or shared with) to B (or BF3) (1)
.....................................................................................................................................
(3)
(Total 15 marks)

24. Sketch a diagram to show the shape of a molecule of NH3 and indicate on your
diagram how this molecule is attracted to another NH3 molecule in liquid ammonia.

(3)
(Total 3 marks)

25. (a) Define the term electronegativity.

the ability of an atom to attract a pair of electrons towards itelf in a covalent bond
...................................................................................................................................
power of an atom (allow element) to attract electron(s) (1)
in a covalent bond (1)
...................................................................................................................................
(2)

(b) State and explain the trend in electronegativity of the elements across Period 3 from
sodium to chlorine.
increases
Trend. ........................................................................................................................
number of protons increases
Explanation. ..............................................................................................................
nuclear charge increases (1)
attracting electrons in same shell (1)
...................................................................................................................................

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

Mill Hill High School 19

 (c) State the bond type in sodium oxide and the bond type in sulphur dioxide. In each case,
explain the link between the bond type and the electronegativity of the elements involved.
ionic bond
Bond type in sodium oxide. .......................................................................................
oygen and sodium share electrons and oygen is more electronegative
Explanation. .............................................................................................................
big difference in electronegativity (1)
...................................................................................................................................

...................................................................................................................................
covalent
Bond type in sulphur dioxide. ..................................................................................
smaller electronegativity difference (1)
Explanation. .............................................................................................................
(4)
(Total 9 marks)

26. (a) Co-ordinate bonding can be described as dative covalency. In this context, what is the
meaning of each of the terms covalency and dative?
shared electron pair (1)
Covalency....................................................................................................................
both electrons from one atom (1)
one pair of electrons being shared
Dative .........................................................................................................................
(2)

(b) Write an equation for a reaction in which a co-ordinate bond is formed.

A + : B A : B (or NH3 + H+ NH4 + etc) equation (1)
final species (1)
.....................................................................................................................................
(2)

(c) Why is sodium chloride ionic rather than covalent?

because chloride gains one electron from sodium resulting in them both to have full outer shell
.....................................................................................................................................
chlorine is more electronegative than sodium (1)
an electron transfers from sodium to chlorine (1)
.....................................................................................................................................

.....................................................................................................................................
(2)

(d) Why is aluminium chloride covalent rather than ionic?

they share electrons not donate
.....................................................................................................................................
smaller electronegativity difference (1)
so more equal sharing (1)
.....................................................................................................................................

.....................................................................................................................................
(2)

(e) Why is molten sodium chloride a good conductor of electricity?

ions are free to move
.....................................................................................................................................
mobile (free) ions (1) (1)

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 (f) Explain, in terms of covalent bonding, why the element iodine exists as simple molecules
whereas the element carbon does not.
carbon forms 4 bonds (1)
.....................................................................................................................................
gives a macromolecule (1)
iodine forms only one bond (1)
.....................................................................................................................................

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

.....................................................................................................................................
(3)
(Total 12 marks)

27. (a) Describe the nature and strength of the bonding in solid calcium oxide.
ionic bonding which is strong
.........................................................................................................................
strong (accept if reasonably qualified) (1)
electrostatic attractions or similar such as “held” (1)
.........................................................................................................................
between ions held in a lattice (1)

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

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

(b) Use the kinetic theory to describe the changes that take place as calcium oxide is
heated from 25°C to a temperature above its melting point.
particles vibrate less
.........................................................................................................................
vibrations (1)
.........................................................................................................................
increase (1)
as temperature increases until the vibrations are so violent that
the ions break free at the melting point.
.........................................................................................................................
(some indication of translational movement of the particles) (1)

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

(c) State two properties of calcium oxide that depend on its bonding.
have ionic lattice so cant conduct electricity, high mmp and bp
.........................................................................................................................
high melting point/boiling point (1)
electrical conductivity when molten (or in solution) (1)
.........................................................................................................................

.........................................................................................................................
(2)
(Total 8 marks)

28. What is a covalent bond?

shared pair of electrons between two metals or non metals
.....................................................................................................................................
(1)
(Total 1 mark)

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29. (a) Figure 1 shows some data concerned with halogens.

Boiling point of
Element Electronegativity
hydride / K

Fluorine 4.0 293

Chlorine 3.0 188

Bromine 2.8 206

Iodine 2.5 238

Figure 1

(i) Define the term electronegativity.

power / tendency / ability to attract electrons [must be plural]
not gain (1)
...........................................................................................................................

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

...........................................................................................................................
(2)

(ii) Explain the trend in boiling points from hydrogen chloride to hydrogen iodide.
going down the group, the boiling point increases as the electronegativity decreases
...........................................................................................................................
van der Waals’ forces / induced dipole - induced dipole / intermolecular
attractions increase (1)
...........................................................................................................................
as Mr increases / number of electrons increases (1)
size / radius / number of shells increase
...........................................................................................................................

...........................................................................................................................
(2)

(iii) Explain why hydrogen fluoride does not fit this trend.
fluoride is the most electronegative
...........................................................................................................................
higher due to hydrogen bonding / (strong) dipole - dipole attractions (1)
caused by large (difference in) electronegativity of fluorine / clear
...........................................................................................................................
indication (1)
that intermolecular forces in HF are stonger than in (ii)
...........................................................................................................................
(2)

(b) The oxygen atoms in the sulphate ion surround the sulphur in a regular tetrahedral shape.

(i) Write the formula of the ion.

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

(ii) State the O–S–O. bond angle.

...........................................................................................................................
(1)
(Total 8 marks)

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30. (a) State the type of bonding in a crystal of potassium bromide.
covalent
Type of bonding..........................................................................................................
(1)

(b) Sketch a diagram to show the shape of a BrF3 molecule. Show on your sketch any
lone pairs of electrons in the outermost shell of bromine and name the shape.

Sketch

trigonal bipyramid

Name of shape...................................................................................................

(3)
(Total 4 marks)

31. (a) (i) State one feature which molecules must have in order for hydrogen bonding to occur
between them.
have hydrogen
...........................................................................................................................
hydrogen atom bonded to highly electronegative atom / to N, O
or F / hydrogen
...........................................................................................................................
containing molecule with a strong dipole (1) (1)

(ii) Give the name of the type of intermolecular bonding present in hydrogen sulphide,
H2S, and explain why hydrogen bonding does not occur.
van der waals and hydrogen bonding doesnt occur bc cant bond to any hydorgens
...........................................................................................................................
van der Waals’ / (induced or temporary) dipole-dipole (1)
sulphur not sufficiently electronegative / too large / only small
...........................................................................................................................
difference in
electronegativity (1)
(2)

(iii) Account for the much lower boiling point of hydrogen sulphide (–61 °C) compared
with that of water(100 °C).
intermolecular attractions in H2S much weaker / in H2O are stronger (1)
than the hydrogen bonding in water / so less energy needed to
...........................................................................................................................
overcome forces (1)

...........................................................................................................................
(2)

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 (b) Protein molecules are composed of sequences of amino acid molecules that have joined
together, with the elimination of water, to form long chains. Part of a protein chain is
represented by the graphical formula given below.

R O R O R O R

C C N C C N C C N C

H H H H H H H

Explain the formation of hydrogen bonding between protein molecules.

both C=O and N–H bond polar / correct polarity of both bonds
.....................................................................................................................................
shown (1)

since electronegativity N>H and O>C (1)

.....................................................................................................................................
H– bonding between –H+ and = O– in different molecules
(can allow H– bonding in same molecules if clear that
.....................................................................................................................................
folding / higher order
structure is being referred to) (1)
.....................................................................................................................................
using lone pair of electrons on O atom (could be on diagram)
(1)

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

.....................................................................................................................................
(4)
(Total 9 marks)

32. (a) Describe the bonding found in metals.

metallic bonding, electrostatic forces of attraction between metal ions and sea of delocalised electrons
.....................................................................................................................................
(lattice of) metal ions / positive charges / cations not nuclei (1)
with a ‘sea’ of/delocalised electrons not cloud (1)
.....................................................................................................................................
held together by (electrostatic) attraction / forces between ions / nuclei and
electrons / opposite charges (not negative ions) (1)
.....................................................................................................................................

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

(b) Use data from table above and your knowledge of the bonding in these metals to explain
why the melting point of magnesium is higher than that of sodium.
Mg / Mg2+ smaller than Na / Na+ metallic radius smaller / Mg close packed (1)
.....................................................................................................................................
Mg / Mg2+ higher charge than Na / Na+ (1)
magnesium contributes more electrons than Na (1)
therefore stronger (electrostatic) attractions / stronger metallic bond(ing) (1)
.....................................................................................................................................

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

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

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 (c) State and explain the similarities and differences in electrical conductivity of sodium,
graphite and diamond.
diamond and sodium cannot conduct electricity like graphite and the reason for this is because
.....................................................................................................................................
graphite has a free electron thats not bonded therefore its free to move around and conduct electricity
.....................................................................................................................................
sodium and graphite conduct, diamond does not (1)
.....................................................................................................................................
delocalised or free electrons in graphite (1)
single bonded structure of diamond / diamond has no free or delocalised e– (1)
conduction due to delocalised electrons flowing (1)
.....................................................................................................................................

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

.....................................................................................................................................
(4)
(Total 10 marks)

33. The table below contains electronegativity values for the Period 3 elements, except chlorine.

Element Na Mg Al Si P S Cl Ar

Electronegativity 0.9 1.2 1.5 1.8 2.1 2.5 no

value

(a) How can electronegativity values be used to predict whether a given chloride is likely to be
ionic or covalent?
because if theres a big difference in electronegativity then it will be covalent
....................................................................................................................................
large difference in electronegativity ionic (1)
small difference in electronegativity covalent (1)
....................................................................................................................................
(2)

(b) State the type of bonding in sodium oxide.

ionic
....................................................................................................................................
(1)
(Total 3 marks)

34. The diagram below shows how a water molecule interacts with a hydrogen fluoride molecule.

H
δ+ δ–
O H F
H

(a) What is the value of the bond angle in a single molecule of water?
120
....................................................................................................................................
(1)

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 (b) Explain your answer to part (a) by using the concept of electron pair repulsion.
4 electron pairs round O (1)
....................................................................................................................................
tetrahedral (or 109°) (1)
lone pairs repel more than bonding pairs (1)
....................................................................................................................................
angle < 109° (or less than tetrahedral angle) (1)

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

....................................................................................................................................
(4)

(c) Name the type of interaction between a water molecule and a hydrogen fluoride molecule
shown in the diagram above.
hydrogen bonding (1)
....................................................................................................................................
(1)

(d) Explain the origin of the δ+ charge shown on the hydrogen atom in the diagram.

....................................................................................................................................
F more electronegative than H (1)
pulls electrons from H (1)
....................................................................................................................................
(2)

(e) When water interacts with hydrogen fluoride, the value of the bond angle in water changes
slightly. Predict how the angle is different from that in a single molecule of water and
explain your answer.
> 105° (or increases) (1)
Prediction ...................................................................................................................
lone pair more like bonding
Explanation ................................................................................................................
pair

does not repel so strongly (1)

....................................................................................................................................
(2)
(Total 10 marks)

35. (a) State which one of the elements neon, sodium, magnesium, aluminium and silicon has
the lowest melting point and explain your answer in terms of the structure and bonding
present in that element.
sodium neon
Element with lowest melting point ..............................................................................
weaker van der waals forces and least amount of electrons so needs little to no
Explanation .................................................................................................................
energy to break the bonds

.....................................................................................................................................
free atoms (1) weak van der Waals forces (1)

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

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 (b) State which one of the elements neon, sodium, magnesium, aluminium and silicon has the
highest melting point and explain your answer in terms of the structure and bonding present
in that element.
silicon
Element with highest melting point ............................................................................
has strongest van der waals forces and more electrons and shells therefore needs the most
Explanation .................................................................................................................
amount of energy to break the bonds
.....................................................................................................................................
macromolecular (1)
covalent bonds (1)
.....................................................................................................................................
(3)
(Total 6 marks)

36. Diamond and graphite are both forms of carbon.

Diamond is able to scratch almost all other substances, whereas graphite may be used as a
lubricant. Diamond and graphite both have high melting points.

Explain each of these properties of diamond and graphite in terms of structure and bonding.
Give one other difference in the properties of diamond and graphite.
diamond can do that because it has 4 carbon atoms bonded and graphite can do that because the layers can slide over (Total 9 marks)
eachother due to the one free electron/carbon and they have high mp because theyre held by strong covalent bonds
that require alot of energy to break. One difference is that graphite can conduct electricity whilst diamond cannot

37. Iodine and diamond are both crystalline solids at room temperature. Identify one similarity in the
bonding, and one difference in the structures, of these two solids.
Explain why these two solids have very different melting points.
both are giant lattice structures however iodine is not held by strong covalent bonds like diamond therefore (Total 6 marks)
it doesnt require as much energy to break the bonds

38. Phosphorus exists in several different forms, two of which are white phosphorus and red
phosphorus. White phosphorus consists of P4 molecules, and melts at 44°C. Red phosphorus is
macromolecular, and has a melting point above 550°C.

Explain what is meant by the term macromolecular. By considering the structure and bonding
present in these two forms of phosphorus, explain why their melting points are so different.
,macromolecular have giant covalent lattice structures that are held by strong covalent bonds and have very (Total 5 marks)
high mps due to the fact that alot of energy is required to break the bonds

39. (a) Predict the shapes of the SF6 molecule and the AlCl 4– ion. Draw diagrams of these species
to show their three-dimensional shapes. Name the shapes and suggest values for the bond
angles. Explain your reasoning.
(8)

(b) Perfume is a mixture of fragrant compounds dissolved in a volatile solvent.

When applied to the skin the solvent evaporates, causing the skin to cool for a short time.
After a while, the fragrance may be detected some distance away. Explain these
observations.
(4)
(Total 12 marks)

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40. (a) Iodine and graphite crystals both contain covalent bonds and yet the physical properties of
their crystals are very different.
For iodine and graphite, state and explain the differences in their melting points and in their
electrical conductivities.
(9)

(b) Draw the shape of the BeCl2 molecule and explain why it has this shape.

(2)
(Total 11marks)

41. (a) The table below gives the melting point for each of the Period 3 elements Na – Ar.

Element Na Mg Al Si P S Cl Ar
Melting point / K 371 923 933 1680 317 392 172 84

In terms of structure and bonding, explain why silicon has a high melting point, and why
the melting point of sulphur is higher than that of phosphorus.
si is a marcomolecular giant covalent structure so held by strong covalent bonds which will need alot of energy to break (7)
the bonds

(b) Draw a diagram to show the structure of sodium chloride. Explain, in terms of bonding,
why sodium chloride has a high melting point.
lots of electrons on outer shell meaning ti will need more energy to break the bonds (4)
(Total 11 marks)

42. Explain the meaning of the term periodicity as applied to the properties of rows of elements
in the Periodic Table. Describe and explain the trends in atomic radius, in electronegativity
and in conductivity for the elements sodium to argon.
idk u dont need to know maybe (13)
(Total 13 marks)

43. (a) Describe the structure of, and bonding in, three different types of crystal. Illustrate your
answer with a specific example of each type of crystal and sketch labelled diagrams of the
structures. In each case, explain how the ability to conduct electricity is influenced by the
type of bonding.
(18)

(b) Explain how the concept of bonding and lone (non-bonding) pairs of electrons can be used
to predict the shape of, and bond angles in, a molecule of sulphur tetrafluoride, SF4.
Illustrate your answer with a sketch of the structure.
(8)
lone pairs can tell us by how much the bond angle will be decreases due to the fact that lone pairs
repel much stronger than bond pairs which is how we can work out the bond angle of a shape (Total 26 marks)

44. Sketch a graph to show how the melting points of the elements vary across Period 3 from sodium
to argon. Account for the shape of the graph in terms of the structure of, and the bonding in, the
elements.
(Total 21 marks)

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45. (a) With the aid of diagrams, describe the structure of, and bonding in, crystals of sodium
chloride, graphite and magnesium. In each case, explain how the melting point and the
ability to conduct electricity of these substances can be understood by a consideration of
the structure and bonding involved.
(23)

(b) Explain how the electron-pair repulsion theory can be used to predict the shapes of the
molecules H2O and PF5. Illustrate your answer with diagrams of the molecules on which
the bond angles are shown.
(7)
(Total 30 marks)

QoL Bonding Both covalent (linked

M1 Q of L both macromolecular/giant atomic/giant covalent/giant molecular; 1 statement) 1
M2 C atoms in diamond joined to 4 other C atoms / diagram with min 5 C Structure Iodine = molecular /I2 (stated or
atoms i.e. shows tetrahedral shape / coordination number = 4; 1 in diagram) 1
M3 C atoms in graphite joined to 3 other C atoms diagram with clear [treat incorrect diagram as contradiction]
extended hexagonal plane/pattern i.e. shows trigonal planar shape / Diamond = giant
coordination number = 3; 1 molecular/macromolecular/giant 1
M4 diamond hard / crystal strong; 1 covalent / giant atomic (stated only)
(not diamond stronger than graphite) Reference to van der Waals’ /dipole-dipole
M5 because of 3-D structure / rigid structure / not layered; 1 = contradiction
M6 graphite (soft) as layer can slide over each other; 1 QoL Iodine Weak van der Waals’ forces /
M7 Q of L as only (weak) van der Waals’ forces between layers; 1 induced dipole-induced 1
dipole
Melting point (for either allotrope) Diamond Covalent bonds would need to
M8 covalent bonds must be broken / overcome; 1 be broken 1
M9 which are strong / many / hard to break; 1 Many / strong covalent bonds OR much
(M9 tied to M8) energy needed 1
Other difference
M10 diamond is non-conductor of electricity, graphite is conductor 1
OR appropriate difference in appearance;
SF6 shown as octahedral / square based bipyramid (1)
Bond angle: 90° or 180° and 90° (1)
giant lattice (1) Shape = octahedral (1)
of covalent bonds (1)
need to break covalent bonds to melt red phosophorus (1)
need to break Van der Waal’s forces to melt white phosphorus (1)
covalent bonds are stronger than Van der Waal’s forces (1)

Equal repulsion between 6 bonding or shared electron pairs QoL (1)

AlCl4– shape shown as tetrahedral (1)

Bond angle = 109° to 109.5° (1)
Shape = tetrahedral (1)

(Equal repulsion between) 4 bonding pairs or

shared electron pairs (1)

(b) Solvent has low bp or weak intermolecular forces or evaporates quickly (1)
(Solvent) needs energy to evaporate (to overcome intermolecular forces)
or valid reference to latent heat of vaporisation (or evaporation is
endothermic) (1)
Energy taken from the skin (and so it cools) (1)
Fragrance or perfume (molecule) slowly spreads (through the room) (1)
By random movement or diffusion (of the perfume / fragrance) (1)

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