AQA GCSE Combined Science (8464), Higher tier · Chemistry › Bonding, structure, and the properties of matter › Chemical bonds, ionic, covalent and metallic
Practise Metallic bonding. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
How the atoms in a metal are held together: a giant structure of positive ions in a regular pattern, with delocalised electrons that are free to move through it. It is usually tested with 2 to 3 mark 'describe' questions or diagram labelling, and it is the key to explaining the properties of metals.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
State that metals have giant structuresThe atoms in a metal are arranged in a regular pattern in a giant structure.
4
Describe what delocalised electrons areThe outer shell electrons of metal atoms are delocalised: free to move through the whole structure.
5
Describe the metallic bondStrong electrostatic attraction between positive metal ions and the shared delocalised electrons.
6
Explain why the metal particles are positive ionsEach atom has lost its outer electrons to the delocalised electrons, so it has more protons than electrons.
7
Draw and label a diagram of metallic bondingRegular rows of positive ions with electrons between them, labelled 'delocalised electrons'.
Notes
The structure of a metal
Metals have giant structures of atoms arranged in a regular pattern, in layers.
The electrons in the outer shell of each metal atom are delocalised: they do not belong to any one atom and are free to move through the whole structure.
Once an atom has lost its outer electrons in this way, it is a positive ion. So a metal can be described as positive ions surrounded by delocalised electrons.
The metallic bond
The delocalised electrons are shared by all the ions. This sharing gives strong metallic bonds.
The bond is the strong electrostatic attraction between the positive metal ions and the negative delocalised electrons.
The attraction acts throughout the giant structure, so there are a very large number of strong bonds.
Alloys have metallic bonding too: they are mixtures of a metal with other elements, with delocalised electrons throughout.
Drawing metallic bonding
Draw regular rows of circles, each marked + (or with the ion's charge, e.g. 2+ for magnesium).
Draw electrons (e− or small dots) scattered between the ions and label them 'delocalised electrons'.
Like any model, this shows only a tiny part of the structure and is not to scale.
Why metallic bonding matters
Metallic bonding explains the properties of metals: strong bonds give high melting points, layers of ions allow metals to be bent and shaped, and delocalised electrons that can move make metals conduct electricity and thermal energy.
You use these ideas in 'Properties of metals and alloys' and 'Metals as conductors'.
Cheatsheet
Metal = giant structure of atoms in a regular pattern (layers)
Outer shell electrons are delocalised: free to move through the whole structure
Metallic bond = strong electrostatic attraction between positive ions and delocalised electrons
Charge on each ion = number of outer electrons given up (Na+, Mg2+)
Alloys have metallic bonding too
Strong bonds → high melting points; delocalised electrons → conduction
How to answer each type of question
Label a diagram of metallic bonding
2 marks4
The particles in regular rows marked + are positive (metal) ions.
The small particles spread between them are delocalised electrons.
Example. A diagram of a metal shows regular rows of large circles, each marked +, with many small particles marked e− spread between them. (a) Name the particles marked +. (b) Name the particles marked e−.
Say it is a giant structure of atoms (positive ions) in a regular pattern, in layers.
Say the outer electrons are delocalised and free to move through the structure.
Say there is strong electrostatic attraction between the positive ions and the delocalised electrons.
Example. Describe the structure and bonding in copper.
Show the model answer
A giant structure of copper atoms (positive ions) arranged in a regular pattern / in layers (1). The outer shell electrons are delocalised, so they can move through the whole structure (1). There is strong electrostatic attraction between the positive ions and the delocalised electrons (1).
Explain why the particles in a metal are ions
2 marks6
Say how many outer electrons each atom has lost and that they have become delocalised.
Link this to the charge: more protons than electrons.
Example. In a diagram of magnesium, each magnesium particle is labelled 2+. Explain why.
Show the model answer
Each magnesium atom loses its two outer shell electrons, which become delocalised (1). So each particle has two more protons than electrons, giving a charge of 2+ (1).
Shortcuts and memory tricks
Picture rows of positive ions held together by a cloud of moving electrons. The 'glue' is the attraction between + and −.
Labelling check: the + particles are ions (not atoms or protons); the moving particles are electrons (not ions).
One structure explains every metal property: strong bonds → high melting point; layers → can be bent; delocalised electrons → conducts.
Where marks are lost
Saying the positive ions move. It is the delocalised electrons that move; the ions stay in their positions.
Writing 'free electrons' or 'a sea of electrons' without the word 'delocalised'. Use 'delocalised' to be safe.
Describing the bond as attraction between atoms, or between electrons. It is between positive ions and delocalised electrons.
Calling metallic bonding ionic because the diagram shows ions. There are no negative ions in a metal.
Exam technique
In 'describe the bonding' questions, three things score: a giant regular structure, delocalised electrons, and attraction between positive ions and delocalised electrons.
If you draw a diagram, label both the positive ions and the delocalised electrons.
Call metallic bonds 'strong': you need this word later to explain high melting points.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Metals have metallic bonding. What are delocalised electrons?
Electrons that are free to move through the whole structure.
The electronic structure of magnesium is 2,8,2. In magnesium metal, the outer electrons of each atom are delocalised. What is the charge on the positive ions in magnesium metal?
2+
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Metals have metallic bonding.
(a) Complete the sentence. Tick (✓) one box. Metals consist of giant structures of atoms arranged in a ................[1]
random pattern
regular pattern
single layer
small molecule
(b) What are delocalised electrons?[1]
(c) Which electrons become delocalised in a metal? Tick (✓) one box.[1]
All of the electrons
Electrons in the inner shells
Electrons in the outer shell
One electron from every ten atoms
(d) Are metallic bonds strong or weak?[1]
Show the answer and mark scheme
(a)Answer: regular pattern
(b)Answer: Electrons that are free to move through the whole structure.
electrons that are free to move (through the whole structure)
(c)Answer: Electrons in the outer shell
(d)Answer: strong
strong
Question 2Medium5 marks
The electronic structure of magnesium is 2,8,2. In magnesium metal, the outer electrons of each atom are delocalised.
(a) What is the charge on the positive ions in magnesium metal?[1]
(b) How many delocalised electrons are there in a piece of magnesium that contains 5000 atoms?[1]
(c) The positive ions in a metal repel each other. Explain why the structure does not fall apart.[2]
(d) Magnalium is an alloy of magnesium and aluminium. What type of bonding is present in magnalium?[1]
Show the answer and mark scheme
(a)Answer: 2+
2+
(b)Answer: 10 000
10 000
(c)Answer: The delocalised electrons are attracted to all the positive ions; this strong electrostatic attraction holds the ions together.
the (negative) delocalised electrons attract the positive ions
this (strong) electrostatic attraction holds the structure together / is stronger than the repulsion
(d)Answer: metallic
metallic
Question 3Hard4 marks
Magnesium metal and magnesium oxide both have giant structures. Magnesium conducts electricity when solid; magnesium oxide does not.
Compare the bonding in magnesium with the bonding in magnesium oxide.[4]
Show the answer and mark scheme
Answer: Both contain Mg2+ ions held in giant structures by strong electrostatic attraction. In magnesium the attraction is between the ions and delocalised electrons, which are free to move; in magnesium oxide it is between Mg2+ and O2− ions, which are fixed in place in the solid.
both contain positive magnesium ions (Mg2+) in a giant structure
in both, the bonding is a strong electrostatic attraction
in magnesium, the attraction is between the positive ions and delocalised electrons
in magnesium oxide, the attraction is between oppositely charged ions (Mg2+ and O2−) / electrons have been transferred to oxygen
the delocalised electrons in magnesium are free to move (so it conducts), but the ions in solid magnesium oxide are fixed in place (so it does not)