AQA GCSE Combined Science (8464), Higher tier · Chemistry › Bonding, structure, and the properties of matter › Chemical bonds, ionic, covalent and metallic
Practise Chemical bonds. 11 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.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Name the three types of strong bondIonic, covalent and metallic.
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.
4
Name the particles in each type of bondIonic: oppositely charged ions; covalent: atoms sharing pairs of electrons; metallic: positive ions and delocalised electrons.
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.
6
Describe what the electrons do in each bondElectrons are transferred (ionic), shared in pairs (covalent) or delocalised (metallic).
7
Tell chemical bonds from intermolecular forcesChemical bonds hold atoms or ions together and are strong; intermolecular forces are weak forces between separate molecules.
Notes
The three types of strong bond
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.
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.
Cheatsheet
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
How to answer each type of question
Give the type of bonding in a substance
1 mark each4
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
Covalent goes with atoms sharing pairs of electrons.
Metallic goes with positive ions and delocalised electrons. Cross out any option that does not fit any bond.
Example. Draw one line from each type of bonding to the particles it involves. Types of bonding: ionic, covalent, metallic Particles: A atoms that share pairs of electrons; B positive ions and delocalised electrons; C oppositely charged ions; D molecules that share protons
Show the model answer
ionic → C (1) covalent → A (1) metallic → B (1)
Explain how you know the type of bonding
2 marks5
Say what type of element each one is (metal or non-metal).
Link this to the bond and say what the electrons do: transferred, shared in pairs or delocalised.
Example. Hydrogen chloride, HCl, has covalent bonding. Explain why.
Show the model answer
Hydrogen and chlorine are both non-metals (1). So their atoms share a pair of electrons (1).
Shortcuts and memory tricks
Metal meets non-metal = ionic; non-metals together = covalent; metals together = metallic.
Sense check with everyday examples: table salt is ionic, water is covalent, copper wire is metallic.
Where marks are lost
Treating hydrogen as a metal because it sits above Group 1. It is a non-metal, so HCl, H2O and CH4 are covalent.
Mixing up the words: ionic bonding is a transfer of electrons, not sharing; covalent bonding is sharing pairs of electrons.
Saying covalent bonds are weak. Covalent bonds are strong; it is the forces between molecules that are weak.
Forgetting that alloys have metallic bonding.
Calling the particles in an ionic compound 'molecules'. Ionic compounds are made of ions.
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.
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]
(a) Which two substances have ionic bonding? Tick (✓) two boxes.[2]
Magnesium oxide
Carbon dioxide
Brass
Chlorine
Potassium fluoride
Iron
(b) Explain why carbon dioxide has covalent bonding.[2]
(c) Brass is an alloy of copper and zinc. Name the type of bonding in brass.[1]
(d) Describe the forces that hold the particles together in ionic bonding.[2]
Show the answer and mark scheme
(a)Answer: Magnesium oxide; Potassium fluoride
(b)Answer: Carbon and oxygen are both non-metals, so their atoms share pairs of electrons.
carbon and oxygen are (both) non-metals
(so their atoms) share pairs of electrons
(c)Answer: metallic
metallic
(d)Answer: Strong electrostatic forces of attraction between oppositely charged ions.
(strong) electrostatic forces of attraction
between oppositely charged ions
Question 3Hard6 marks
Sodium, chlorine and sodium chloride each have a different type of strong bonding.
Compare the bonding in sodium chloride, chlorine and sodium. Your answer should refer to the particles involved and the forces that hold them together.[6]
Show the answer and mark scheme
Answer: NaCl: ionic — electron transfer gives Na+ and Cl− ions held by strong electrostatic attraction in all directions. Cl2: covalent — atoms share a pair of electrons attracted to both nuclei; small molecules. Na: metallic — positive ions in a regular lattice attracted to delocalised electrons.
sodium chloride has ionic bonding (a metal combined with a non-metal)
each sodium atom transfers one electron to a chlorine atom, forming Na+ and Cl− ions
strong electrostatic attraction between oppositely charged ions, acting in all directions (giant lattice)
chlorine has covalent bonding between non-metal atoms
the two chlorine atoms share a pair of electrons; the shared pair is attracted to both nuclei
chlorine consists of small molecules, Cl2
sodium has metallic bonding
sodium atoms / positive ions are arranged in a regular pattern and their outer electrons are delocalised
strong electrostatic attraction between the positive ions and the delocalised electrons
Marked with levels of response: the full level descriptors are in the app.