The Metallic Model

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Metallic Bonding

Metal atoms are tightly packed in lattice structures.
Outer shell electrons become delocalised and are free to move throughout the structure.
Metal atoms become positively charged when they lose their outer electrons.
The positive charges repel each other and keep the neatly arranged lattice in place.
Metallic bonding is the strong electrostatic attraction between positive metal centres and the 'sea' of delocalised electrons.

Metallic bonding and malleability

Properties of Metals

Metals are malleable (can be hammered into sheets) and ductile (can be drawn into wires).
Layers of metal ions can slide over each other when a force is applied, while delocalised electrons allow the metal to retain its structure without breaking bonds.
Metals are typically strong and hard due to strong electrostatic attraction between cations and electrons and the closely packed structure of metal ions.
Metals conduct electricity in both solid and liquid states because mobile electrons can freely move.
When a potential difference is applied, delocalised electrons move towards the positive terminal.
Metals are good thermal conductors: vibrating cations transfer kinetic energy to delocalised electrons, which rapidly carry it through the metal.
Metals have high melting and boiling points because strong electrostatic forces between cations and delocalised electrons require large amounts of energy to overcome.

Trends in Metallic Bond Strength

The strength of a metallic bond depends on the charge of the metal ion, the radius of the metal ion, and the number of delocalised electrons.
Greater charge on the metal ion means more delocalised electrons and a greater charge difference, leading to stronger electrostatic attraction.
Smaller ionic radius means the metal ion exerts a greater attraction on the sea of delocalised electrons, strengthening the metallic bond.
Increasing the number of delocalised electrons per atom, increasing positive charge, and decreasing ionic size all increase the strength of metallic bonding.

Melting Points Across a Period

Across Period 3, the number of valence electrons increases: Na (1), Mg (2), Al (3).
Aluminium ions are also smaller than magnesium or sodium ions.
These factors lead to stronger metallic bonding from Na to Al.
Stronger metallic bonding requires more energy to break the lattice, so melting points increase across the period.
Melting point data: Na = 371 K, Mg = 922 K, Al = 933 K.

Melting Points Down a Group

Down a group, the size of the cation increases.
This decreases the attraction between the outer electrons and the metallic lattice.
Therefore, the melting point decreases down the group.
Melting point data for Group 1: Na = 371 K, K = 337 K, Rb = 312 K.

Uses of Metals

The choice of metal for a job depends on properties such as malleability/ductility, melting/boiling point, density, reactivity, electrical conductivity, strength, toxicity, lustre, thermal conductivity, strength-to-weight ratio, corrosion resistance, and sonority.
Aluminium is used in food cans because it is non-toxic and resistant to corrosion and acidic food stuffs.
Copper is used in electrical wiring because it is a good electrical conductor and malleable/ductile.
Stainless steel is used for cutlery as it is strong and resistant to corrosion.

Transition Metals: Definition and Location

A transition metal is an element with an incomplete d-subshell or an element that can form at least one stable cation with an incomplete d-subshell.
Scandium and zinc are d-block elements but not transition metals: Sc only forms Sc³⁺ ([Ar] 3d⁰) and Zn only forms Zn²⁺ ([Ar] 3d¹⁰).
The first transition series is Ti to Cu.
Transition metals are located in the d-block: Period 4 from Ti to Cu, Period 5 from Zr to Ag.
Periods 6 and 7 are complicated by the presence of the f-block lanthanides and actinides.

Physical Properties of Transition Metals

Transition metals have a metallic lattice structure: layers of positive ions in a sea of delocalised electrons.
The 3d and 4s subshells are close in energy, so transition metals can delocalise d-electrons to form metallic bonds.
Transition metals form metallic bonds involving both s- and d-electrons, giving more delocalised electrons and stronger electrostatic attraction.
This results in high melting points and high electrical conductivity.
Period 4 transition metals have higher melting points than Group 1 and Group 2 metals (exception: Be has a melting point of 1,287 °C due to its small size).
The three most conductive metals are Ag > Cu > Au; copper is most used in electrical cables due to cost and conductivity.

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1.Which of the following types of bonds does the statement 'electrostatic attraction between cations and delocalised electrons' best describe?
Easy
- Ametallic
- Bionic
- Chydrogen
- Ddipole-dipole
2.Which of the following materials only contains one type of bonding?
Easy
- Abrass
- Bgraphite
- Cice
- Diodine crystals
3.Substance L melts at 660 °C and conducts electricity when solid and when molten. What is the likely identity of substance L?
Medium
- AAl
- Bgraphite
- CLi₂O
- DNaCl
4.What is the correct order of decreasing melting points for the Group 1 metals Na, K, Rb and Cs?
Medium
- ANa > K > Rb > Cs
- BNa > K > Cs > Rb
- CCs > Rb > K > Na
- DK > Na > Rb > Cs
5.Which of the following Period 3 metals would have the highest melting point?
Medium
- AAl
- BMg
- CNa
- DK
6.Which of the following species has the highest melting point?
Medium
- A1s² 2s² 2p⁶ 3s² 3p²
- B1s² 2s² 2p⁶ 3s²
- C1s² 2s² 2p⁶ 3s¹
- D1s² 2s² 2p⁶ 3s² 3p¹
7.Which statement about metals is correct?
Medium
- AThe melting point of vanadium is higher than that of calcium
- BScandium is a transition metal
- CTransition metals are good conductors of electricity due to the incomplete d-subshell
- DThe electronic configuration of Zn²⁺ is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰
8.Which of the following metals will have the greatest ability to conduct electricity?
Hard
- AAl
- BMg
- CNa
- DLi

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9.Sodium and magnesium are both Period 3 elements. Compared to sodium, why is magnesium less reactive?
Hard
- AMagnesium has a larger nuclear charge and a smaller atomic radius, giving stronger nuclear attraction for its outer electrons
- BMagnesium has a smaller atomic radius and a smaller nuclear charge
- CMagnesium has a larger atomic radius and a larger nuclear charge
- DMagnesium has a larger atomic radius and a smaller nuclear charge
10.Which is the correct order of increasing electrical conductivity?
Hard
- ANa < Mg < Al < Ag
- BAl < Mg < Na < Ag
- CMg < Al < Na < Ag
- DAg < Na < Mg < Al
11.Metals can conduct electricity in both the solid and liquid states because delocalised electrons are mobile in both states.
Easy
True or false?
12.When a potential difference is applied across a metal, the delocalised electrons move towards the negative terminal.
Medium
True or false?
13.Which of the following factors increase the strength of a metallic bond? (select all that apply)
Medium
- AIncreasing the charge on the metal ion
- BDecreasing the size of the metal ion
- CIncreasing the number of delocalised electrons per metal atom
- DIncreasing the ionic radius of the metal ion
- EDecreasing the number of delocalised electrons per metal atom
14.Which of the following statements about transition metals are correct? (select all that apply)
Medium
- AThey can delocalise both s- and d-electrons to form metallic bonds
- BThey generally have higher melting points than Group 1 and Group 2 metals
- CScandium and zinc are transition metals by the strict definition
- DThey have particularly good electrical conductivity due to a large number of delocalised electrons
- EThe first transition series runs from Ti to Cu
15.Match each property of metals to its correct explanation.
Medium
- Malleability
- Electrical conductivity
- Thermal conductivity
- High melting point
- Layers of metal ions can slide over each other while delocalised electrons maintain the structure
- Delocalised electrons move freely towards the positive terminal when a potential difference is applied
- Vibrating cations transfer kinetic energy to delocalised electrons, which carry it rapidly through the lattice
- Strong electrostatic attraction between cations and delocalised electrons requires large amounts of energy to overcome
16.Arrange the following Period 3 metals in order of increasing melting point.
Medium
- Na
- Mg
- Al
17.Which of the following is the best definition of a transition metal?
Easy
- AAn element with an incomplete d-subshell or that can form at least one stable cation with an incomplete d-subshell
- BAny element found in the d-block of the periodic table
- CAn element that forms only one stable ion with a full d-subshell
- DAn element that has a partially filled s-subshell
18.Match each property of copper to the correct explanation.
Medium
- Electrical conductivity
- Malleability
- Thermal conductivity
- Delocalised electrons move towards the positive terminal when a potential difference is applied
- Layers of positive ions slide over each other without breaking the metallic lattice
- Vibrating cations transfer kinetic energy to delocalised electrons, which carry it rapidly through the metal
19.Arrange the following Group 1 metals in order of decreasing melting point.
Medium
- Na
- K
- Rb
- Cs
20.Which of the following statements about metallic bonding are correct? (select all that apply)
Medium
- AThe delocalised electrons are not bound to any specific atom
- BThe metal cations are held in the lattice by electrostatic attraction to the delocalised electrons
- CThe delocalised electrons are attracted towards the negative terminal when a potential difference is applied
- DThe metal atoms become positively charged when their outer electrons are delocalised
- EThe positive metal centres repel each other, which keeps the lattice in place
21.Which of the following changes would increase the strength of the electrostatic attraction in a metallic lattice? (select all that apply)
Hard
- AIncreasing the number of delocalised electrons per metal atom
- BIncreasing the number of positive charges on the metal centres in the lattice
- CDecreasing the size of the metal ions
- DIncreasing the size of the metal ions
- EDecreasing the number of delocalised electrons per metal atom
22.Alloying a metal usually makes it harder than the pure metal because the different-sized atoms disrupt the regular lattice and prevent the layers from sliding easily.
Medium
True or false?
23.Which statement best describes the bonding in solid magnesium?
Medium
- APositive Mg2+ ions in a sea of delocalised electrons, held by strong electrostatic attraction
- BMg2+ and Mg2- ions held together by ionic bonding
- CMagnesium atoms held together by covalent bonds between neighbouring atoms
- DMagnesium atoms held together by weak intermolecular forces
24.Which statement best explains why magnesium has a considerably higher boiling point than sodium?
Hard
- AMg2+ ions have more delocalised electrons and a smaller radius than Na+ ions, so the electrostatic attraction is stronger and more energy is needed to break the lattice
- BMagnesium has a higher molar mass than sodium, so its boiling point is higher
- CMagnesium has weaker intermolecular forces than sodium
- DMagnesium forms covalent bonds, which are stronger than the metallic bonds in sodium
25.Which principal property of a metal makes it suited to manufacturing shaped objects such as railings?
Medium
- AMalleability, because the layers of ions can slide over each other when a force is applied
- BElectrical conductivity, because delocalised electrons can move through the lattice
- CThermal conductivity, because vibrating cations transfer kinetic energy
- DDensity, because the ions are closely packed in the lattice
26.Many alloys are harder than their constituent metal elements alone. Which statement best explains this?
Hard
- AThe different-sized atoms in the alloy disrupt the regular lattice, so the layers of ions cannot slide over each other as easily
- BThe alloy contains stronger covalent bonds between the different metal atoms
- CThe alloy has more delocalised electrons, which makes the lattice more rigid
- DThe alloy contains ions of lower charge, which increases the electrostatic attraction
27.A sample of an unknown metal M is tested. It has a high melting point, is a good conductor of electricity in the solid state, and its electrical conductivity is higher than that of magnesium but lower than that of silver. Which metal is most likely to be M?
Medium
- ASodium
- BAluminium
- CCopper
- DLithium
28.The melting points of three consecutive Period 3 metals are given: Na = 371 K, Mg = 922 K, Al = 933 K. Which statement best explains the small difference between Mg and Al compared with the large difference between Na and Mg?
Medium
- AAluminium has a much larger ionic radius than magnesium, weakening the metallic bond
- BThe increase in charge from Mg to Al is offset by other factors such as packing structure, so the melting point rise is smaller
- CAluminium has fewer delocalised electrons than magnesium
- DMagnesium has a higher charge than aluminium, so its melting point should be higher
29.The melting point of sodium is 371 K and that of potassium is 337 K. Which statement correctly explains this difference?
Medium
- APotassium ions have a smaller radius than sodium ions, so the metallic bond is weaker
- BPotassium has more delocalised electrons per atom than sodium
- CPotassium ions have a larger radius than sodium ions, so the electrostatic attraction to the delocalised electrons is weaker
- DPotassium has a higher charge than sodium, so its metallic bond is stronger
30.A student predicts that the melting point of aluminium should be much higher than that of magnesium because Al3+ has a higher charge than Mg2+. The data show Al = 933 K and Mg = 922 K. What is the best conclusion?
Medium
- AThe prediction is wrong because aluminium has fewer delocalised electrons than magnesium
- BThe prediction is correct in principle, but the actual difference is small because other factors such as metal packing also affect melting point
- CThe prediction is wrong because magnesium has a higher charge than aluminium
- DThe prediction is correct and the data must be incorrect
31.Which of the following statements correctly describe the thermal conductivity of metals? (select all that apply)
Hard
- AVibrating cations transfer kinetic energy to neighbouring cations by collision
- BDelocalised electrons are bound to specific atoms and cannot move
- CDelocalised electrons carry increased kinetic energy rapidly through the metal
- DThermal conductivity is due only to the movement of cations through the lattice
- EWhen heated, cations in the lattice vibrate more vigorously
32.A metal is required for the outer casing of a spacecraft, where low density and high strength are important. Which properties of aluminium make it suitable? (select all that apply)
Medium
- AIt has a low density
- BIt is malleable and ductile
- CIt is a good thermal conductor
- DIt is non-toxic
- EIt has a high strength-to-weight ratio
33.Metals are malleable because the layers of metal ions can slide over each other while the delocalised electrons maintain the metallic bonding.
Easy
True or false?
34.Alloying a metal always lowers its melting point because the added atoms disrupt the lattice.
Medium
True or false?
35.Match each metal with the property that best explains its typical use.
Medium
- Copper
- Aluminium
- Stainless steel
- Used in electrical wiring
- Used in food cans
- Used for cutlery
36.Arrange the following metals in order of increasing electrical conductivity.
Medium
- Ag
- Al
- Mg
- Na
37.A metal is found to be very hard, has a high melting point, and is a good conductor of electricity. It forms a chloride that is soluble in water and gives a coloured solution. Which type of metal is it most likely to be?
Hard
- AGroup 1 metal
- BGroup 2 metal
- CTransition metal
- DGroup 3 metal
38.Which of the following statements about the melting points of transition metals compared to s-block metals are correct? (select all that apply)
Hard
- ATransition metals have higher melting points because they can delocalise d-electrons as well as s-electrons
- BTransition metals have lower melting points because their ions are larger
- CThe greater number of delocalised electrons in transition metals leads to stronger electrostatic attraction
- DBeryllium has a higher melting point than some transition metals due to its small atomic size
- EAll s-block metals have higher melting points than all transition metals
39.The electrical conductivity of a metal depends on the number of delocalised electrons per atom and the mobility of those electrons.
Medium
True or false?
40.The melting point of sodium is 371 K and that of rubidium is 312 K. Which statement best explains this trend down Group 1?
Medium
- AThe charge on the metal ion increases down the group, strengthening the metallic bond
- BThe ionic radius increases down the group, decreasing the attraction between the cation and the delocalised electrons
- CThe number of delocalised electrons per atom increases down the group
- DThe metallic bond becomes stronger because the atoms are more tightly packed
41.Using the melting point data for the Period 3 metals, what is the melting point of aluminium in K?
Medium
42.Complete the definition of metallic bonding.
Medium
Metallic bonding is the strong electrostatic attraction between positive metal ____ and a sea of ____ electrons.
43.What name is given to the free-moving electrons in a metal lattice?
Easy
44.Give the name of the property of metals that allows them to be drawn into wires.
Medium
45.Using the melting point data for the Period 3 metals, state the melting point of magnesium in K.
Medium
46.Using the melting point data for the Group 1 metals, state the melting point of rubidium in K.
Medium
47.Complete the description of the structure of a metal.
Medium
The free-moving electrons in a metal are called ____ electrons, and they form a 'sea' around the positive metal ____.
48.Complete the definition of a transition metal.
Medium
A transition metal is an element with an incomplete ____ or an element that can form at least one stable ____ with an incomplete d-subshell.
49.Give the name of the property of a metal that allows it to be hammered into sheets.
Medium
50.Give the name of the most common type of iron alloy.
Medium
51.The melting points of some Period 3 metals are: Na = 371 K, Mg = 922 K, Al = 933 K. Calculate the difference in melting point between aluminium and sodium. Give your answer in K.
Medium
The difference in melting point between Al and Na is ____ K.
52.Using the melting point data for the Period 3 metals (Na = 371 K, Mg = 922 K, Al = 933 K), calculate the mean melting point of these three metals in K. Give your answer to the nearest whole number.
Medium
53.Describe the bonding in solid sodium.
Hard
54.Explain why copper is malleable.
Hard
55.Explain why pure gold is not often used to make jewellery.
Hard
56.Both copper and benzene have delocalised electrons. Explain why copper conducts electricity but benzene does not.
Hard
57.Magnesium is in the same period as sodium, but has a much higher melting point. Explain why.
Hard
58.Using the melting point data for the Period 3 metals, what is the melting point of aluminium in K?
Medium
- A1119 K
- B840 K
- C1026 K
- D933 K
59.Using the melting point data for the Period 3 metals, state the melting point of magnesium in K.
Medium
- A922 K
- B1014 K
- C830 K
- D1106 K
60.Using the melting point data for the Group 1 metals, state the melting point of rubidium in K.
Medium
- A343 K
- B281 K
- C312 K
- D374 K
61.Using the melting point data for the Period 3 metals (Na = 371 K, Mg = 922 K, Al = 933 K), calculate the mean melting point of these three metals in K. Give your answer to the nearest whole number.
Medium
- A816 K
- B742 K
- C668 K
- D890 K

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