Question 1 Medium
How many electrons does a sulfur atom gain to form an ion with a full outer shell? Sulfur is in Group 6.
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Answer: 2
- A full outer shell has 8 electrons.
- Sulfur has 6 outer electrons, so it gains 2.
Ionic bonding and ionic compounds: GCSE Combined Science Chemistry practice questions
A second set of questions on ionic bonding and ionic compounds. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
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Question 2 Medium
Name the type of force that holds the ions together in sodium chloride.
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Answer: electrostatic
- The ions have opposite charges.
- The force is electrostatic attraction.
Question 3 Medium
What is the formula of potassium oxide? The ions are K⁺ and O²⁻.
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Answer: K₂O
- Two K⁺ (2+) balance one O²⁻ (2−).
- So the formula is K₂O.
Question 4 Medium
Does molten sodium chloride conduct electricity? Answer yes or no.
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Answer: yes
- When molten, the ions are free to move.
- So it conducts.
Question 5 Hard
Write a half equation for chlorine atoms forming chloride ions, Cl₂ + ... → ...
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Answer: Cl₂ + 2e⁻ → 2Cl⁻
- Each Cl atom gains one electron.
- Two atoms in Cl₂ gain two electrons.
Question 6 Hard
What is the formula of calcium nitrate? The ions are Ca²⁺ and NO₃⁻. Use brackets.
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Answer: Ca(NO₃)₂
- One Ca²⁺ needs two NO₃⁻.
- Put the nitrate in brackets: Ca(NO₃)₂.
Question 7 Hard
Magnesium oxide has a higher melting point than sodium oxide. Give the reason in terms of the ions.
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Answer: Mg²⁺ has a greater charge than Na⁺ so the attraction is stronger
- Mg²⁺ and O²⁻ have bigger charges than Na⁺ and O²⁻.
- The attraction is stronger, so more energy is needed.
Question 8 Hard
Why does dissolved potassium bromide conduct electricity?
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Answer: the ions are free to move
- It contains K⁺ and Br⁻ ions.
- In solution the ions are free to move and carry charge.
Question 9 Medium
What is the name of the compound NaCl?
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Answer: sodium chloride
- The metal is sodium.
- The non-metal gives chloride.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
What is an ion?
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An atom, or group of atoms, with an electric charge.
Check 2
What happens in ionic bonding?
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A metal atom transfers electrons to a non-metal atom.
Check 3
What charge do Group 1 ions have?
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1+.
Check 4
What charge do Group 2 ions have?
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2+.
Check 5
What charge do Group 6 ions have?
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2−.
Check 6
What charge do Group 7 ions have?
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1−.
Check 7
What is a giant ionic lattice?
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A regular arrangement of positive and negative ions held by strong electrostatic forces.
Check 8
Why do ionic compounds have high melting points?
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A lot of energy is needed to overcome the strong forces between the ions.
Check 9
When do ionic compounds conduct electricity?
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When molten or dissolved in water.
Check 10
Why do solid ionic compounds not conduct?
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The ions are fixed in place and cannot move.
Check 11
What is the formula of magnesium oxide?
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MgO.
Check 12
What is the formula of aluminium oxide?
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Al₂O₃.
Check 13
Why does MgO have a higher melting point than NaCl?
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Its ions have larger charges, so the attraction is stronger.
Check 14
What is the half equation for sodium forming an ion?
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Na → Na⁺ + e⁻.
Check 15
What does the electrostatic force act between?
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Oppositely charged ions.
Check 16
What is the formula of calcium hydroxide?
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Ca(OH)₂.
Check 17
What is the formula of sodium oxide?
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Na₂O.
Check 18
What is the formula of magnesium chloride?
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MgCl₂.
Check 19
What is the half equation for chlorine forming chloride ions?
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Cl₂ + 2e⁻ → 2Cl⁻.
Check 20
What type of ion does a non-metal form?
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A negative ion.
Check 21
What type of ion does a metal form?
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A positive ion.
Check 22
Do ionic compounds contain separate molecules?
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No. They are giant lattices of ions.
Check 23
Why does molten sodium chloride conduct electricity?
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The ions are free to move and carry charge.
Check 24
What does the formula of an ionic compound show?
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The simplest ratio of ions.
Check 25
How many electrons does a Group 1 atom lose to form an ion?
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One.
Check 26
What ending does the name of a compound of a metal and one non-metal usually have?
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-ide, for example sodium chloride.
Check 27
What ending do sulfate, nitrate and carbonate have in common?
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-ate. The negative ion contains oxygen.
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