S2.3 The metallic model

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Practice exam-style IB Chemistry questions for The metallic model, aligned with the syllabus and grouped by topic.

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Question 1

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SL • Paper 1A

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The best description of a metallic bond is an electrostatic attraction between:

A.

a lattice of cations and delocalized electrons

B.

neutral atoms and shared pairs between adjacent atoms

C.

positive ions and a lattice of localized electron pairs

D.

negative ions and a lattice of metal cations

Question 2

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SL • Paper 1A

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Copper is used for electrical wiring. The particle-level reason for this use is that copper contains:

A.

mobile cations that move through the solid lattice

B.

mobile delocalized electrons that carry charge

C.

localized covalent bonds that transfer charge along chains

D.

alternating positive and negative ions that exchange electrons

Question 3

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SL • Paper 1A

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A metal spoon quickly becomes hot when one end is placed in hot water. The best explanation is that thermal energy is transferred through the metal by:

A.

mobile electrons and vibrations of closely packed ions

B.

electrons becoming localized between neighbouring ions

C.

movement of metal ions from the hot end to the cold end

D.

breaking of metallic bonds throughout the lattice

Question 4

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SL • Paper 1A

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Aluminium can be rolled into thin foil without shattering. The best explanation is that:

A.

covalent bonds break and reform between fixed pairs of atoms

B.

oppositely charged ions realign to form stronger ionic bonds

C.

layers of cations can slide while remaining attracted to delocalized electrons

D.

the lattice contains neutral atoms with no electrostatic attractions

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Question 5

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Many transition elements have much higher melting points than group 1 metals. The best explanation is that transition elements:

A.

contain delocalized d-electrons that increase electron density in the metallic bond

B.

form negative ions that attract surrounding positive ions strongly

C.

have no mobile electrons, so the lattice is rigid

D.

contain only localized d-electrons between fixed pairs of atoms

Question 6

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HL • Paper 1A

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Zinc is not classified as a transition element in the usual definition. The reason is that:

A.

zinc does not conduct electricity as a solid

B.

zinc has no electrons in its d sublevel

C.

zinc atoms are in the p-block of the periodic table

D.

zinc and its common $2+$ ion have full d sublevels

Question 7

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HL • Paper 1A

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A transition element conducts electricity in the solid state. In the metallic model, this is mainly because:

A.

d-electrons remain localized in covalent bonds throughout the lattice

B.

electrons are transferred between fixed positive and negative ions

C.

both s and d electrons may contribute mobile charge carriers

D.

only the nuclei move through the lattice under a potential difference

Question 8

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SL • Paper 2

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A student models a piece of magnesium metal as a regular arrangement of positive ions in a sea of electrons.

Define a metallic bond.

[1]

Explain why magnesium conducts electricity in the solid state.

[2]

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Question 9

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Copper is used for electrical wiring. Aluminium is used to make thin food containers and foil.

Suggest why copper is suitable for electrical wiring, referring to its bonding.

[2]

State one property, other than electrical conductivity, that makes aluminium suitable for making foil.

[1]

Question 10

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SL • Paper 1A

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The melting points of group 1 metals decrease from lithium to caesium. The best explanation for this trend is that down the group:

A.

metal ion radius increases, so attraction to delocalized electrons becomes weaker

B.

cation charge decreases, so attraction to electrons becomes weaker

C.

the lattice changes from metallic bonding to covalent bonding

D.

the number of delocalized electrons per atom increases, so bonding becomes weaker

Question 11

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HL • Paper 1A

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The trend in melting points across a row of d-block metals is less smooth than the trend from sodium to magnesium to aluminium. The best explanation is that across the d-block:

A.

metallic bonding is absent for most d-block elements

B.

d-electron involvement and crystal structure both affect metallic bonding

C.

atomic radius increases steadily and is the only factor involved

D.

all atoms contribute exactly one more delocalized electron than the previous element

Question 12

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HL • Paper 1A

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Tungsten is used in applications where a metal must remain solid at very high temperatures. The property and bonding feature most relevant to this use are:

A.

high melting point due to strong metallic bonding involving d-electrons

B.

high electrical resistance due to absence of delocalized electrons

C.

low density due to weak attraction between large cations and electrons

D.

low melting point due to a filled outer p sublevel

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Question 13

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A strip of aluminium can be bent into a new shape without breaking, whereas a crystal of sodium chloride shatters when struck.

State the term used to describe the ability of a metal to be hammered or pressed into a new shape.

[1]

Explain, using bonding models, why aluminium bends but sodium chloride shatters.

[3]

Question 14

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HL • Paper 2

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Chromium is a transition element with a high melting point compared with sodium.

State what is meant by a transition element.

[1]

Explain why delocalized d-electrons can lead to a high melting point in transition elements.

[2]

Question 15

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HL • Paper 2

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Nickel and copper are transition metals used in electrical components.

Explain why transition metals are usually good electrical conductors.

[2]

State one factor, other than the number of delocalized electrons, that can affect the measured electrical conductivity of a transition metal sample.

[1]

Question 16

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HL • Paper 2

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Tungsten is used in applications where a metal must remain solid at very high temperatures.

Suggest why tungsten has a very high melting point in terms of the metallic model for transition elements.

[2]

State one additional property, other than high melting point, that should be considered when selecting a metal for a high-temperature engineering use.

[1]

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Question 17

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SL • Paper 1B

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A student collected data for selected period 3 elements to investigate changes in metallic character.

Element	Structure	Melting point / $^\circ\text{C}$	Electrical conductivity / $\text{S m}^{-1}$
Sodium	giant metallic lattice	98	$2.1 \times 10^{7}$
Magnesium	giant metallic lattice	650	$2.3 \times 10^{7}$
Aluminium	giant metallic lattice	660	$3.8 \times 10^{7}$
Silicon	giant covalent lattice	1410	$1.0 \times 10^{-4}$
Phosphorus	simple molecular structure	44	$1.0 \times 10^{-15}$
Sulfur	simple molecular structure	115	$1.0 \times 10^{-17}$
Chlorine	simple molecular structure	-101	$1.0 \times 10^{-20}$
Argon	monatomic structure	-189	$1.0 \times 10^{-20}$

Identify the elements in the table that show typical metallic electrical conductivity.

[1]

Describe the trend in electrical conductivity across the selected period 3 elements.

[1]

Explain the difference in electrical conductivity between aluminium and sulfur using the metallic model.

[2]

Question 18

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SL • Paper 1B

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Copper wire was heated and its electrical resistance was measured at different temperatures.

State how the resistance of the copper wire changes as temperature increases.

[1]

Explain this change in resistance using the metallic model.

[2]

Suggest one use of copper that depends on its electrical conductivity.

[1]

Question 19

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SL • Paper 1A

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The correct order of increasing metallic bond strength for the period 3 metals sodium, magnesium and aluminium is:

A.

$\text{Mg} < \text{Na} < \text{Al}$

B.

$\text{Al} < \text{Mg} < \text{Na}$

C.

$\text{Na} < \text{Mg} < \text{Al}$

D.

$\text{Na} < \text{Al} < \text{Mg}$

Question 20

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HL • Paper 1A

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A graph of melting point against atomic number for the first-row d-block elements shows generally high values but an irregular pattern across the row. The conclusion best supported by this graph is that:

A.

several factors affect metallic bonding across the d-block

B.

d-electrons prevent electrical conductivity in transition metals

C.

all d-block elements have identical metallic bond strength

D.

d-block melting points are controlled only by cation charge

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Question 21

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The melting points of lithium, sodium and potassium decrease down group 1.

Metal ion	Metal ion radius / pm	Melting point / $^\circ\text{C}$
$\text{Li}^+$	76	180.5
$\text{Na}^+$	102	97.8
$\text{K}^+$	138	63.5

State the trend in metal ion radius down group 1.

[1]

Explain why the melting points decrease from lithium to potassium.

[3]

Question 22

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SL • Paper 2

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Sodium, magnesium and aluminium are metallic elements in period 3. Their melting points increase strongly from sodium to magnesium and remain high for aluminium.

Compare the charges of the metal ions formed in the simple metallic model for sodium, magnesium and aluminium.

[1]

Explain why aluminium is expected to have stronger metallic bonding than sodium.

[3]

Question 23

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HL • Paper 2

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Zinc is in the d-block but is not classified as a transition element under the usual IB definition. Iron is classified as a transition element.

Distinguish between zinc and iron in terms of d sublevel occupancy and classification as transition elements.

[2]

Suggest why this classification is relevant when using d-electrons to explain metallic bonding.

[1]

Question 24

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SL • Paper 1B

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The graph shows melting point plotted against ionic radius for group 1 metals.

Describe the relationship shown by the graph.

[1]

Explain this relationship using the metallic model.

[2]

A student used the graph to predict the melting point of francium. Suggest one reason why this prediction is uncertain.

[1]

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Question 25

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SL • Paper 1B

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Samples of aluminium and sodium chloride were placed under the same sideways force. Their structures before and after the force was applied are represented in the stimulus.

Describe the difference in behaviour of the two solids when the sideways force is applied.

[1]

Explain why aluminium is malleable using the metallic model.

[2]

Suggest why sodium chloride does not show the same malleability.

[1]

Question 26

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SL • Paper 1B

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A materials engineer is selecting a metal for long overhead electrical cables. The table compares possible materials.

Metal	Electrical conductivity / $10^{7}$ $\text{S m}^{-1}$	Density / $\text{g cm}^{-3}$	Cost / $ kg $^{-1}$
Aluminium	3.5	2.7	2.5
Copper	5.9	8.9	9.0
Steel	0.6	7.8	0.9

Using the data, identify the most suitable metal for long overhead cables and justify your choice.

[2]

Explain why metals such as copper and aluminium conduct electricity.

[1]

State one factor, other than those shown in the table, that could affect the final choice of material.

[1]

Question 27

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HL • Paper 1B

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The table compares selected s-block metals and transition elements.

Metal	Type	Melting point / $^\circ\text{C}$
Sodium	s-block	98
Lithium	s-block	181
Magnesium	s-block	650
Copper	transition element	1085
Nickel	transition element	1455
Iron	transition element	1538

Compare the melting points of the transition elements with those of the s-block metals in the table.

[1]

Explain the high melting points of the transition elements using delocalized d-electrons.

[2]

Explain why the transition elements in the table conduct electricity.

[1]

Question 28

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HL • Paper 1B

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A component in a high-temperature furnace must remain solid while conducting electricity. The table compares four metals.

Metal	Melting point / $^\circ\text{C}$	Density / g cm $^{-3}$	Cost / $ kg $^{-1}$
Aluminium	660	2.70	2.5
Copper	1085	8.96	9.0
Iron	1538	7.87	0.9
Tungsten	3422	19.3	35.0

Identify the most suitable metal for the furnace component using the data.

[1]

Explain why tungsten has a very high melting point using the metallic model for transition elements.

[2]

State one limitation of using tungsten for the component that is shown by the data.

[1]

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Question 29

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A student uses database values of electrical conductivity for period 3 elements to support the metallic model.

Period 3 element	Electrical conductivity / S m $^{-1}$
Na	$2.1 \times 10^7$
Mg	$2.3 \times 10^7$
Al	$3.7 \times 10^7$
Si	$4.0 \times 10^{-4}$
P	$1.0 \times 10^{-15}$
S	$1.0 \times 10^{-16}$
Cl	$1.0 \times 10^{-15}$

Identify the period 3 element in the data that is best described as a semiconductor rather than a typical metal.

[1]

Evaluate how the data support the metallic model.

[3]

Question 30

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HL • Paper 2

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The melting points of consecutive first-row d-block metals show an irregular pattern rather than a smooth increase across the period.

Describe the pattern shown by the melting point data for the d-block metals.

[1]

Explain why the trend is less evident across the d-block than across sodium, magnesium and aluminium.

[3]

Question 31

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HL • Paper 2

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Aluminium is a p-block metal and iron is a transition metal. Both conduct electricity and have metallic bonding, but their metallic models are not identical.

Compare the origin of the delocalized electrons in aluminium and iron.

[2]

Explain why a simple comparison based only on cation charge and radius is less reliable for iron than for aluminium.

[2]

Question 32

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SL • Paper 1B

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The table gives data for the metallic elements sodium, magnesium and aluminium.

Element	Cation charge	Metal ion radius / pm	Delocalized electrons per atom	Melting point / $^\circ\text{C}$
sodium	$1^+$	102	1	98
magnesium	$2^+$	72	2	650
aluminium	$3^+$	53	3	660

Describe two changes in the metallic model from sodium to aluminium shown by the data.

[2]

Explain why aluminium has stronger metallic bonding than sodium.

[2]

Suggest why melting point is useful evidence for metallic bond strength.

[1]

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Question 33

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The graph shows melting points across the first-row d-block elements from scandium to zinc.

Describe two features of the melting point pattern shown in the graph.

[2]

Explain why the trend in melting points is less regular across the d-block than across the metallic elements sodium, magnesium and aluminium.

[2]

Suggest why zinc has a relatively low melting point compared with many neighbouring d-block metals.

[1]

Question 34

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HL • Paper 1B

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The table shows electrical conductivity and simplified electron information for selected metals.

Metal	Electron config.	d-electrons	Conductivity / MS m $^{-1}$
Ti	$[\text{Ar}]\ 3d^{2}\ 4s^{2}$	2	2.4
V	$[\text{Ar}]\ 3d^{3}\ 4s^{2}$	3	5.7
Cr	$[\text{Ar}]\ 3d^{5}\ 4s^{1}$	5	7.9
Mn	$[\text{Ar}]\ 3d^{5}\ 4s^{2}$	5	0.6
Fe	$[\text{Ar}]\ 3d^{6}\ 4s^{2}$	6	10.0
Co	$[\text{Ar}]\ 3d^{7}\ 4s^{2}$	7	17.2
Ni	$[\text{Ar}]\ 3d^{8}\ 4s^{2}$	8	14.3
Cu	$[\text{Ar}]\ 3d^{10}\ 4s^{1}$	10	59.6

Identify the metal with the greatest electrical conductivity in the table.

[1]

Explain why transition elements are generally good electrical conductors.

[2]

Evaluate the claim: “A transition element with more d-electrons always has higher electrical conductivity.”

[2]

Question 35

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SL • Paper 2

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The table shows selected physical properties of sodium, magnesium and aluminium at room temperature.

Metal	Melting point / $^\circ\text{C}$	Electrical conductivity / $10^{7}$ S m $^{-1}$
Sodium	98	2.1
Magnesium	650	2.3
Aluminium	660	3.8

Use the data to analyse the trend in metallic bonding from sodium to aluminium.

I.

State the trend in melting point from sodium to aluminium.

[1]

II.

Explain the trend in melting point in terms of metallic bonding.

[3]

Aluminium is used for overhead power cables whereas sodium is not. Evaluate this choice using the metallic model and one additional property from the data.

[3]

Question 36

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SL • Paper 2

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A student investigates the melting points of group 1 metals and uses the trend to predict the melting point of francium.

Interpret the trend shown by the graph.

I.

State the trend in melting point down group 1.

[1]

II.

Explain this trend using the metallic model.

[2]

Evaluate the reliability of using the graph to predict the melting point of francium.

[3]

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Question 37

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SL • Paper 2

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A metal sheet and an ionic crystal are tested for electrical conductivity and behaviour when struck with a hammer.

Explain the electrical conductivity of the metal.

I.

Describe metallic bonding.

[1]

II.

Explain why the metal conducts electricity as a solid.

[2]

Compare the behaviour of the metal and the ionic crystal when struck.

[3]

Question 38

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HL • Paper 2

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Tungsten is a transition element used in high-temperature electrical contacts. Potassium is an s-block metal.

Property	Tungsten	Potassium
Electron configuration	[Xe] 4f $^{14}$ 5d $^{4}$ 6s $^{2}$	[Ar] 4s $^{1}$
Valence electrons available to metallic bonding / atom	6	1
d-electrons in valence shell / atom	4	0
Melting point / $^\circ\text{C}$	3422	63.5
Electrical conductivity / $10^{7}$ S m $^{-1}$ at 293 K	1.79	1.39

Compare the metallic bonding in tungsten and potassium.

I.

Describe the role of delocalized $d$ -electrons in transition elements.

[2]

II.

Explain why tungsten has a much higher melting point than potassium.

[3]

Explain why tungsten can conduct electricity, and state one reason why its measured conductivity may differ from the value predicted by a simple metallic model.

[2]

Question 39

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HL • Paper 2

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Chromium is a transition element used in some electrical contacts and high-temperature alloys. The resistance of a chromium sample is measured at different temperatures.

Metal / data set	Temperature / $^\circ\text{C}$	Resistance / Ω	Melting point / $^\circ\text{C}$	Electrical conductivity / $10^7$ S m $^{-1}$
Chromium sample	20	1.75	—	—
Chromium sample	40	1.87	—	—
Chromium sample	60	2.00	—	—
Chromium sample	80	2.14	—	—
Chromium sample	100	2.29	—	—
Chromium	—	—	1907	0.79
Sodium	—	—	97.8	2.10

Use the metallic model to explain the conductivity and temperature behaviour of chromium.

I.

Explain why chromium conducts electricity.

[2]

II.

Explain the trend in resistance with temperature.

[2]

Discuss why a metal with a very high melting point does not necessarily have the highest electrical conductivity.

[2]

Question 40

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HL • Paper 1B

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The graph shows melting points of metallic elements across period 4, from potassium to zinc.

Compare the melting point trend for potassium and calcium with the trend across the d-block part of the graph.

[2]

Explain why many of the d-block metals have higher melting points than potassium and calcium.

[2]

Evaluate the statement: “Melting point increases steadily across period 4 metals.”

[1]

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Question 41

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HL • Paper 1B

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Two students used online databases to investigate whether delocalized d-electrons affect melting points of metals. Their summarized results are shown.

Metal	Block	Student A melting point	Student B melting point / $^\circ\text{C}$	Source
Li	s	—	181	NIST
Na	s	—	98	CRC
Mg	s	—	650	RSC
Ca	s	—	842	NIST
Ti	d	$1941\ \text{K}$	1668	CRC
V	d	$2183\ \text{K}$	1910	NIST
Cr	d	$1907^\circ\text{C}$	1907	RSC
Mn	d	$1519\ \text{K}$	1246	CRC
Fe	d	$1811\ \text{K}$	1538	NIST
Cu	d	$1085^\circ\text{C}$	1085	RSC

Identify which student has the stronger database investigation and give one reason.

[2]

Explain how Student B’s results support the metallic model for transition elements.

[2]

Suggest why Student B should not conclude that d-electrons are the only factor controlling melting point.

[1]

Question 42

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SL • Paper 2

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Copper is used in heat sinks for electronic devices. The graph shows how the electrical resistance of a copper wire changes with temperature.

Relate the particle model of metals to the data and to thermal conduction.

I.

Explain why copper is a good thermal conductor.

[2]

II.

Explain the trend in electrical resistance shown by the graph.

[2]

Discuss why copper is suitable for a heat sink but unsuitable as an electrical insulator.

[3]

Question 43

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SL • Paper 2

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Bronze is an alloy containing copper and tin. Bronze is harder than pure copper but remains metallic.

Use the metallic model to explain why alloys can form.

I.

State what is meant by an alloy.

[1]

II.

Explain why metallic bonding can hold a mixed lattice together.

[2]

Explain why bronze is harder than pure copper but can still conduct electricity.

[4]

Question 44

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HL • Paper 2

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The graph shows melting points of elements across part of period 4, from potassium to copper.

Analyse the pattern in the graph.

I.

Compare the melting points of the s-block metals with those of most transition elements shown.

[2]

II.

Explain why the trend across the d-block is less evident than the trend from sodium to aluminium in period 3.

[3]

Discuss whether melting point data alone can prove that $d$ -electrons are delocalized in transition elements.

[2]

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Question 45

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Iron, copper and zinc are d-block metals. Zinc is commonly not classified as a transition element, whereas iron and copper are.

Apply the definition of transition element and the metallic model.

I.

Explain why iron is classified as a transition element but zinc is not.

[2]

II.

Explain why zinc is still an electrical conductor as a solid metal.

[2]

Compare the expected metallic bond strength in iron and zinc, referring to $d$ -electrons and limitations of the model.

[4]

Question 46

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SL • Paper 2

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A materials engineer is selecting a metal for long overhead power cables. Some properties of copper, aluminium and steel are compared.

Metal	Conductivity / $10^7\ \text{S m}^{-1}$	Density / $\text{g cm}^{-3}$	Tensile strength / MPa	Corrosion resistance
Copper	5.9	8.9	220	high
Aluminium	3.8	2.7	90	high
Steel	1.0	7.8	400	low

Use the data and the metallic model to identify important requirements for overhead power cables.

I.

Identify two properties, other than cost, that should be considered when choosing the metal.

[2]

II.

Explain why metals can be drawn into wires and conduct electricity.

[2]

Evaluate whether aluminium or copper is the better choice for long overhead power cables.

[4]

Question 47

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HL • Paper 2

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Titanium alloys are used for some high-performance aircraft components. Aluminium is used for many lower-temperature aircraft structures.

Material	Density / g cm $^{-3}$	Melting point / $^\circ\text{C}$	Tensile strength / MPa
Titanium	4.5	1670	430
Titanium alloy	4.4	1650	900
Aluminium	2.7	660	300

Explain the metallic properties of titanium and aluminium using the metallic model.

I.

Explain why titanium has a high melting point and conducts electricity.

[3]

II.

Contrast this with aluminium in terms of electron delocalization and melting point.

[2]

Evaluate the choice of a titanium alloy rather than aluminium for a high-temperature aircraft component.

[3]

Question 48

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HL • Paper 2

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A researcher compares vanadium, chromium, manganese, iron, cobalt and nickel as possible high-temperature electrodes. The graph shows their melting points across the first transition series.

Analyse the melting point pattern across these transition elements.

I.

Describe two features of the melting point pattern shown.

[2]

II.

Explain these features in terms of delocalized $d$ -electrons and limitations of the metallic model.

[3]

Evaluate the use of one of these transition metals rather than a group 1 metal as a high-temperature electrode.

[3]

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S2.2 The covalent model

S2.4 From models to materials

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