S2.3 The metallic model
Practice exam-style IB Chemistry questions for The metallic model, aligned with the syllabus and grouped by topic.
Question 1
What is a metallic bond?
A.
Electrostatic attraction between metal cations and delocalized electrons
B.
A shared pair of electrons localized between two atoms
C.
Attraction between instantaneous dipoles in adjacent atoms
D.
Electrostatic attraction between oppositely charged ions in a lattice
Question 2
Why does solid copper conduct electricity?
A.
Its electrons are fixed in covalent bonds between neighbouring atoms
B.
Its copper ions can move freely through the solid lattice
C.
Its delocalized electrons can move through the metallic lattice
D.
Its atoms form molecules that move towards the positive terminal
Question 3
The property that allows aluminium to be rolled into foil is best described as
A.
lustre
B.
volatility
C.
malleability
D.
ductility
Question 4
What contributes to the high thermal conductivity of metals?
A.
Mobile electrons transfer kinetic energy through the lattice
B.
Metal cations travel from the hot end to the cold end
C.
Covalent bonds break and reform along the metal surface
D.
Electrons are transferred permanently from one atom to another
Question 5
Why are many polished metals lustrous?
A.
Metal ions emit light because they move through the lattice
B.
Metallic bonds are directional and align with incoming light
C.
Metal atoms absorb all visible light without reflection
D.
Delocalized electrons interact with and re-emit visible light
Question 6
A transition element is defined as an element that
A.
has a full d sublevel in both the atom and all common ions
B.
has delocalized electrons only from its outer s sublevel
C.
has atoms with an incomplete d sublevel or forms an ion with an incomplete d sublevel
D.
is found in the d-block and always forms only one oxidation state
Question 7
Transition elements conduct electricity because they contain
A.
alternating layers of anions and cations that can slide
B.
mobile delocalized electrons, including possible d-electron contribution
C.
mobile positive ions that flow between lattice positions
D.
localized d-electrons fixed between two neighbouring atoms
Question 8
State the particles between which electrostatic attraction acts in a metallic bond.
[1]
State why the electrons in this model are described as delocalized.
[1]
Question 9
State what is meant by metallic lustre.
[1]
State a use of a metal that depends on lustre.
[1]
Question 10
Define a transition element.
[1]
State why zinc is not a transition element by this definition.
[1]
Question 11
The melting points of group 1 metals generally decrease from lithium to caesium. What is the best explanation?
A.
The atoms become less reactive and so the metallic bond becomes weaker
B.
The metal ion radius increases, weakening attraction to delocalized electrons
C.
The charge on the metal ion increases, weakening the metallic bond
D.
The number of delocalized electrons per atom increases down the group
Question 12
In the simple metallic model, the strongest metallic bonding among Na, Mg and Al is expected in
A.
Mg, because its melting point is close to that of Al
B.
Na, because it has the lowest molar mass
C.
Al, because it forms smaller, more highly charged cations with more delocalized electrons
D.
Na, because its single valence electron is lost most easily
Question 13
Why is zinc not classified as a transition element by the IB definition?
A.
Zn has no electrons in the 3d sublevel
B.
Zn forms only covalent compounds in the solid state
C.
Zn is not able to conduct electricity as a solid
D.
Zn and Zn²⁺ both have a complete 3d sublevel
Question 14
Many transition elements have high melting points because
A.
their cations are all larger than group 1 cations
B.
delocalized d-electrons increase electron density and strengthen metallic bonding
C.
their ions are held together by fixed covalent bonds in molecules
D.
their delocalized electrons are unable to move through the lattice
Question 15
Tungsten is suitable for very high-temperature applications mainly because it has
A.
weak metallic bonding that allows easy reshaping at low temperature
B.
a simple molecular structure with high intermolecular forces
C.
strong metallic bonding involving a high density of delocalized electrons
D.
no delocalized electrons, so it behaves as an insulator
Question 16
What is the effect of delocalized d-electrons in transition metals?
A.
They prevent the movement of electrons under a potential difference
B.
They make the metallic bond directional like a covalent bond
C.
They convert the metallic lattice into an ionic lattice of anions and cations
D.
They increase the density of mobile electronic charge in the metallic structure
Question 17
Copper is used in electrical wiring.
State one metallic property, other than electrical conductivity, that makes copper suitable for wires.
[1]
Explain why copper conducts electricity as a solid.
[1]
Question 18
A student compares the deformation of a metal and an ionic crystal.
State the meaning of malleability.
[1]
Explain why a metal is malleable in terms of its bonding.
[1]
Question 19
Lithium and potassium are group 1 metals.
State which metal has the higher melting point.
[1]
Explain the difference in melting point using the metallic model.
[1]
Question 20
Iron has a much higher melting point than sodium.
State the type of bonding present in solid iron.
[1]
Explain how d-electrons contribute to the high melting point of many transition elements.
[1]
Question 21
Transition metals are used for electrical contacts and structural components.
State the mobile charge carriers in a solid transition metal.
[1]
Explain why transition elements are generally good electrical conductors.
[1]
Question 22
Distinguish between a d-block element and a transition element.
[1]
Give one example of a d-block element that is not classified as a transition element.
[1]
Question 23
The graph shows melting points of group 1 metals plotted against atomic number.
Describe the trend shown in the graph.
[1]
Explain the trend using the metallic model.
[1]
Suggest one reason why extrapolating this graph far beyond the measured metals may be unreliable.
[1]
Question 24
A database extract gives density, electrical conductivity and cost for three metals considered for long-distance cables.
| Metal | Density / g cm⁻³ | Conductivity / % IACS | Cost / US$ kg⁻¹ |
|---|---|---|---|
| Aluminium | 2.70 | 61 | 2.4 |
| Copper | 8.96 | 100 | 8.7 |
| Silver | 10.49 | 106 | 760 |
Identify the metal that would give the lowest mass for the same volume of cable.
[1]
Identify the metal that would be the best electrical conductor.
[1]
Explain why the best conductor may not be the best overall choice for overhead cables.
[1]
Question 25
A metal bends rather than shatters when a force is applied. The best particle-level explanation is that
A.
like charges become aligned and repel strongly along a cleavage plane
B.
layers of cations can slide while attraction to delocalized electrons remains
C.
metal atoms leave the lattice and form a liquid at room temperature
D.
localized electron pairs rotate between pairs of metal atoms
Question 26
The trend in melting points across a row of the d-block is less regular than across Na, Mg and Al because
A.
all d-block elements have identical numbers of delocalized electrons
B.
the cation radius is the only factor that changes across the d-block
C.
d-block elements do not form metallic lattices
D.
d-electron participation and crystal structures vary in more complex ways
Question 27
Compared with sodium, a typical transition metal such as iron has a higher melting point partly because iron
A.
can use d-electrons in the delocalized electron system
B.
forms only Fe⁺ ions with one delocalized electron per atom
C.
contains no delocalized electrons in its solid lattice
D.
has weaker attraction between cations and electrons than sodium
Question 28
A metal saucepan transfers thermal energy rapidly from the base to the food.
State one other use of a metal that depends on high thermal conductivity.
[1]
Explain, using the metallic model, why metals are good thermal conductors.
[1]
Question 29
Sodium, magnesium and aluminium are metallic elements in period 3.
State the charge on the metal cation in the simple metallic model for each element.
[1]
Explain why aluminium is expected to have stronger metallic bonding than sodium.
[1]
Question 30
The melting points across the first row of transition elements do not show as simple a trend as Na, Mg and Al.
State the broad trend in metallic bond strength from Na to Al.
[1]
Explain why the d-block trend is less regular.
[1]
Question 31
Compare the metallic bonding in magnesium and a typical transition element such as chromium.
State one similarity.
[1]
State three differences relevant to bond strength or conductivity.
[1]
Question 32
The table gives electrical conductivity, thermal conductivity and malleability observations for four unknown solids, W, X, Y and Z.
| Solid | Electrical conductivity | Thermal conductivity | When struck |
|---|---|---|---|
| W | very low | low | shatters into pieces |
| X | high | low | crumbles |
| Y | low | moderate | chips but keeps shape |
| Z | high | high | flattens without shattering |
Identify the solid most likely to be a metal.
[1]
Give two pieces of evidence from the table for your answer.
[1]
Suggest a particle-level reason for the electrical conductivity of this solid.
[1]
Suggest one additional physical test that could support the identification.
[1]
Question 33
The graph compares melting points of sodium, magnesium and aluminium.
State the element with the lowest melting point.
[1]
Describe the overall change in melting point from sodium to aluminium.
[1]
Explain the change using two factors in the metallic model.
[1]
State why melting point is useful evidence for metallic bond strength.
[1]
Question 34
The graph compares melting points of selected group 1, group 2 and transition metals.
Identify the category with the highest typical melting points.
[1]
Explain the high melting points of this category in terms of d-electrons.
[1]
State one reason why there is variation within the transition metals shown.
[1]
State why group 1 metals have lower melting points in comparison.
[1]
Question 35
A materials database gives melting point, electrical conductivity and relative cost for tungsten, copper and aluminium for use in a high-temperature electrical device.
| Metal | Melting point / °C | Conductivity / MS m⁻¹ | Relative cost (Al = 1) |
|---|---|---|---|
| Tungsten | 3422 | 18.2 | 18 |
| Copper | 1085 | 59.6 | 3.6 |
| Aluminium | 660 | 37.7 | 1.0 |
Identify the metal most suitable if the operating temperature is the main constraint.
[1]
Explain your choice in terms of metallic bonding.
[1]
Suggest why the chosen metal may not be selected if electrical conductivity and cost are also important.
[1]
Question 36
A metal is being chosen for overhead power cables.
State two metallic properties that are important for this use.
[1]
Suggest why density and cost should also be considered.
[1]
Question 37
Tungsten is used in components that must retain their structure at very high temperatures.
State the key physical property of tungsten required for this use.
[1]
Suggest, in terms of metallic bonding, why tungsten has this property.
[1]
Question 38
A student claims: “All transition metals have identical electrical conductivity because they all have d-electrons.”
State why the claim is partly correct.
[1]
Evaluate the claim by giving three limitations.
[1]
Question 39
The graph shows how electrical resistance of a metal wire changes as temperature increases.
Describe the relationship shown.
[1]
Explain the relationship using the metallic model.
[1]
State the charge carriers in the wire.
[1]
Suggest why the graph does not show superconducting behaviour.
[1]
Question 40
The table lists electron configurations of four d-block elements and their common 2+ ions.
| Element | Atom electron configuration | 2+ ion electron configuration |
|---|---|---|
| Ti | [Ar] 3d² 4s² | [Ar] 3d² |
| Fe | [Ar] 3d⁶ 4s² | [Ar] 3d⁶ |
| Cu | [Ar] 3d¹⁰ 4s¹ | [Ar] 3d⁹ |
| Zn | [Ar] 3d¹⁰ 4s² | [Ar] 3d¹⁰ |
Identify the element that is not a transition element by the IB definition.
[1]
Justify your answer using the electron configurations.
[1]
Identify one element in the table that is a transition element.
[1]
Explain why being in the d-block is not sufficient to classify an element as a transition element.
[1]
Question 41
The graph shows electrical conductivities of several transition metals measured at the same temperature.
Describe the variation shown.
[1]
Explain why all the metals conduct electricity.
[1]
Suggest two factors that could cause different conductivities among transition metals.
[1]
Evaluate the statement: “More d-electrons always means higher conductivity.”
[1]
Question 42
Describe the metallic model of bonding.
[1]
Explain how the metallic model accounts for electrical conductivity, thermal conductivity and malleability in metals.
[1]
Question 43
Outline why metals can be shaped into useful objects without shattering.
[1]
Discuss the selection of a metal for a cooking pan, using metallic bonding and at least two other practical considerations.
[1]
Question 44
Define a transition element and explain why zinc is an exception among common d-block examples.
[1]
Explain the high melting points and electrical conductivity of many transition elements.
[1]
Question 45
The graph shows melting points across the first-row transition elements.
Describe the pattern across the row.
[1]
Explain why the pattern is less regular than the trend from sodium to aluminium.
[1]
Suggest why a simple model based only on cation radius is insufficient for this graph.
[1]
Question 46
State two factors that affect the strength of metallic bonding.
[1]
Compare and contrast the trends in melting point down group 1 and across the metallic elements Na, Mg and Al.
[1]
Question 47
State two characteristic properties of metals and the particle-level reason for each.
[1]
Evaluate the statement: “A material should be chosen for a use simply because it is a metal.” Use examples in your answer.
[1]
Question 48
Outline the trend in metallic bonding from sodium to aluminium.
[1]
Compare this trend with melting point patterns across the d-block, explaining why the d-block pattern is less straightforward.
[1]
Question 49
Explain why transition metals are generally good conductors of electricity.
[1]
Evaluate the claim: “The electrical conductivity and melting point of a transition metal can be predicted only from the number of d-electrons.”
[1]
Question 50
Describe how delocalized d-electrons modify the simple metallic model used for s-block metals.
[1]
Discuss why a transition metal such as tungsten may be selected for a high-temperature electrical component, and why it may still be rejected for some designs.
[1]
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