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Example GCSE Questions

All the questions on this page have featured in previous GCSE level exams at one point or another and this is a key topic - it will be in the exam. So check your answers against the markschemes and learn them! Remember foundation tier questions can also appear in the higher tier paper.



[FT] Identifying ionic bonding from a diagram

Q1: Which TWO of the diagrams below represent ions/ionic bonding?(2 marks) Click on the digram to find out if you're correct.

Incorrect - this is an oxygen atom. A quick way to spot ions at GCSE level is to look for something with a full outer shell, square brackets and a charge in the top right corner.
Correct - this ion has a full outer shell, a charge in the top right hand corner and square brackets. Well done!
Incorrect - remember ions have an overall charge and there are no charges on this diagram.
Correct - this represents an ionic (or crystal) lattice. Well done!
Incorrect - this is a diagram of the arrangment of particles within a solid.
Incorrect - remember ions have an overall charge and there are no charges on this diagram.

[FT] Naming Ionic Compounds

Q2: Name the compound shown in the diagram to the right. (1 mark)

The compound's name is magnesium oxide. When naming an ionic compound the name of the metal comes first, followed by the non-metal. The non-metal's name ending is changed to -ide, i.e. oxygen becomes oxide, sulfur becomes sulfide, etc.
Diagram of Magnesium Oxide's Ionic Lattice

[FT] Describing Ion Formation

Q3: The diagram to the right shows a fluorine atom. Draw a fluoride ion. (2 marks)

The diagram below shows a fluoride ion:
Diagram of a fluoride ion

Marking points: 2 electrons in inner shell, 8 in outer shell (1 mark), correct charge in top right hand corner (1 mark)


Diagram of a fluorine atom

[FT] Electrostatic Attraction

Q4: The diagram to the right is a diagram of sodium chloride. Why do sodium ions attract chloride ions? (1 mark)

Because oppositely charged ions attract each other (1) OR chloride ions are negative and sodium ions are positive (1)


Diagram of sodium chloride's ionic lattice

[FT] Conductivity

Q5: Explain why sodium chloride solution conducts electricity. (1 mark)


Because oppositely charged ions attract each other (1) OR chloride ions are negative and sodium ions are positive (1)

[FT] Forming Ions

Q6: Which of the following elements, i) potassium, ii) beryllium or iii) chlorine, reacts with sodium to form an ionic compound?(1 mark)

Chlorine as it's the only non-metal on the list. For an ionic bond to form you need a metal (to donate electrons) and a non-metal (to gain electrons).


[FT] Ion Formation

Q7: Sodium atoms react with chlorine atoms to form sodium chloride. This is shown in the diagram to the right. Describe this reaction in terms of electrons. (4 marks)

Reaction between sodium and chlorine to form a sodium chloride ion.

Sodium loses (1) chlorine gains (1) one (1) electron (1)

[FT] Ion Formation

Q8: Magnesium reacts with oxygen to form magnesium oxide. State the charge on the ions formed. Use the diagrams to the right to aid you. (2 marks)


Oxygen = 2- (1), Magnesium = 2+ (1).

Oxygen has 6 electrons in its outer shell, therefore it gains 2 (negative) electrons to fill its shell giving it an overall charge of 2-. Magnesium loses 2 (negative) electrons when it forms an ion to give it an overall charge of 2+.

Diagram of an oxygen atom

Diagram of an oxygen atom.

Diagram of a magnesium atom

Diagram of a magnesium atom.


[FT] Melting Point

Q9: Read the sentence below, choose the correct missing word to fill in the gap from the following list i) attract, ii) repel, iii) positive, iv) negative. (1 mark)

Sodium chloride has a high melting point because oppositely charged ions _______ each other strongly. A large quantity of heat energy is required to overcome this attraction.


Attract (1). Remember opposite charges attract!


[FT] Oxidation/Reduction (Redox)

Q10: The diagram to the right shows the formation of sodium chloride. Explain why chlorine is being reduced. (2 marks)


Chlorine has gained (1) electrons (1) second mark often dependant on the first (i.e. you can't get the second mark unless you get the first one).

sodium chloride ion formation

N.B. This question used to be higher tier only - it now appears in both tiers in the most recent syllabus.


[FT] Formulae of Ionic Compounds

Q11: The diagram to the right is a diagram of magnesium oxide. Determine its formula from the diagram.


MgO (1). The ratio of magnesium to oxygen is 1 to 1.

Diagram of an ionic lattice

Key

Pink = Magnesium ion
Yellow = Oxygen ion


[FT] Identifying Ionic Substances

Q12: Which of the following substances is bonded ionically. There may be more than one correct answer. (2 marks)

Correct - sodium is a metal and oxygen is a non-metal. When metals react with non-metals they form ions and bond ionically.
Incorrect - carbon and oxygen are both non-metals. When non-metals react with non-metals they form covalent compounds.
Incorrect - sulfur and oxygen are both non-metals. When non-metals react with non-metals they form covalent compounds. If the "di" confused you - just remember it means two. So dioxide means two oxide ions.
Correct - this compound contains a metal and a non-metal!
Incorrect - Potassium is a metal and therefore forms metallic bonds.
Incorrect - hydrogen and oxygen bond covalently. Unless you're told otherwise in the question treat hydrogen as a non-metal.

[HT] Melting Point

Q13: Under what conditions will sodium chloride conduct electricity. Explain your answer. (3 marks)


When molten (1) OR dissolved (1). The ions are free to move (1). Allowing charge to flow (1)..

AQA have changed what they will accept for the last marking point - be careful when looking at older mark schemes as they're out of date and poor use of scientific language/language which contradicts what's in the syllabus is no longer allowed.


[HT] Ionic Charge - Compound Ions

Q14: Calcium carbonate has the formula CaCO3. The calcium ion has a charge of +2. Calculate the charge on the carbonate ion. (1 mark)


2- (1). The overall charge on the carbonate molecule is zero. So if the calcium ion has a charge of +2 the remainder of the molecule must have a charge of -2 to give a total of zero.


[HT] Formulae of Ionic Compounds

Q15: What is the formula of aluminium oxide? (2 marks)


Al2O3 (2). Aluminium is in group 3, so it has a charge of 3+, oxygen is in group 6 so it has a charge of 2-. Therefore 2 aluminium ions, whose total charge is 6+, and 3 oxygen ions, whose total charge is 6-, are needed to give an overall charge of zero.


[HT] Properties of Ionic Compounds

Q16: Explain why sodium oxide has a high melting point. (4 marks)


It is a giant structure/lattice (1), with strong electrostatic forces of attraction (1) between oppositely charged ions (1) therefore a large quantity of energy is needed to overcome this attraction (1)


[HT] Oxidation/Reduction - Redox

Q17: Sodium reacts with oxygen to form sodium oxide. Explain how oxidation and reduction have taken place in this reaction in terms of the movement of electrons.


Sodium is oxidised (1) as it loses electrons (1). Oxygen is reduced (1) as it has gained electrons(1). Remember OILRIG - Oxidation Is a Loss of electrons, Reduction Is a Gain of electrons.


[HT] Ionic Bonding

Q18: Describe the structure and bonding in sodium chloride. (4 marks)


Lattice/Giant structure (1), contains ions (1), ions present are Na+ and Cl-(1), electrostatic attraction/opposite charges attract (1)


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