AQA GCSE Combined Science Foundation (8464), Foundation tier · Chemistry › Bonding, structure, and the properties of matter › Chemical bonds, ionic, covalent and metallic
Practise Chemical bonds. 6 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
There are three types of strong chemical bond: ionic, covalent and metallic. This subtopic is about telling them apart from the elements involved and the particles they hold together. It comes up as quick 1 to 3 mark questions, often a table to complete, and it underpins every explanation later in this topic.
Key facts
Three types of strong bond: ionic, covalent, metallic
Ionic: metal + non-metal; oppositely charged ions
Covalent: non-metals; atoms share pairs of electrons
Metallic: metals and alloys; positive ions and delocalised electrons
Hydrogen is a non-metal, so HCl and CH4 are covalent
Notes
The three types of strong bond
diagram
A chemical bond holds particles together in an element or compound. There are three types, and all of them are strong.
Ionic bonding: the particles are oppositely charged ions. It happens in compounds formed from a metal combined with a non-metal.
Covalent bonding: the particles are atoms that share pairs of electrons. It happens in most non-metal elements and in compounds of non-metals.
Metallic bonding: the particles are atoms that share delocalised electrons (outer electrons that are free to move through the whole structure). It happens in metals and alloys.
The three types of strong chemical bond.
What happens to the electrons
Ionic: electrons are transferred from the metal atoms to the non-metal atoms, making positive and negative ions.
Covalent: electrons are shared in pairs. Each shared pair of electrons is one covalent bond.
Metallic: the outer shell electrons leave the metal atoms and become delocalised, leaving positive metal ions.
How to decide the type of bonding
Find each element in the periodic table. Metals are on the left and in the centre; non-metals are on the right. Hydrogen is a non-metal.
Metal + non-metal (e.g. NaCl, MgO, CaF2) → ionic.
Non-metals only, whether an element or a compound (e.g. Cl2, H2O, CO2, NH3) → covalent.
A metal element or an alloy (e.g. Cu, Fe, brass) → metallic.
Chemical bonds are not the same as intermolecular forces. Intermolecular forces are much weaker forces between separate molecules. You need this difference to explain the properties of small molecules and polymers.
How to answer each type of question
Give the type of bonding in a substance
1 mark eachGrade 4
Decide whether each element in the substance is a metal or a non-metal.
Apply the rule: metal + non-metal = ionic; non-metals only = covalent; metal or alloy = metallic.
Write the name of the bond exactly: ionic, covalent or metallic.
Example. Give the type of bonding in each substance. (a) potassium iodide, KI (b) sulfur dioxide, SO2 (c) zinc, Zn (d) bronze, an alloy of copper and tin
Sense check with everyday examples: table salt is ionic, water is covalent, copper wire is metallic.
Exam technique
Use the exact phrases: 'oppositely charged ions', 'share pairs of electrons', 'delocalised electrons'. These are what mark schemes look for.
If a question says 'in terms of electrons', say what the electrons do: transferred, shared or delocalised.
When asked to explain, give the evidence (metal or non-metal) as well as the type of bond. The name of the bond on its own usually earns only one mark.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name the three types of strong bondIonic, covalent and metallic.
Grade 4
Choose the bond type from the elementsMetal + non-metal gives ionic bonding; non-metals only give covalent bonding; metals (elements or alloys) have metallic bonding.
Grade 4
Name the particles in each type of bondIonic: oppositely charged ions; covalent: atoms sharing pairs of electrons; metallic: positive ions and delocalised electrons.
Grade 5
Decide the bond type from a formulaUse the periodic table to decide whether each element in, for example, KBr, SO2 or Zn is a metal or a non-metal.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Here is a list of substances.
magnesium oxide, MgO
carbon dioxide, CO2
brass
chlorine, Cl2
potassium fluoride, KF
iron, Fe
Explain why carbon dioxide has covalent bonding.
Carbon and oxygen are both non-metals, so their atoms share pairs of electrons.
There are three types of strong chemical bond: ionic, covalent and metallic. Which type of bonding involves delocalised electrons?
metallic
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
There are three types of strong chemical bond: ionic, covalent and metallic.
(a) Give the type of bonding in each substance. sodium chloride water copper[3]
(b) Complete the sentence. Tick (✓) one box. Ionic bonding occurs in compounds formed from ................[1]
metals combined with non-metals
non-metals only
metals only
noble gases
(c) Which describes the particles in covalent bonding? Tick (✓) one box.[1]