GCSE Science Quiz - Chemistry - Covalent Bonding (AQA) (Questions)

To do well in GCSE Science students should have a good understanding of the fundamental ideas in chemistry. This is the fourth of six quizzes aimed at reinforcing these ideas and it focusses on covalent bonding of atoms in compounds (molecules).

When elements react, atoms of each element join with atoms of other elements to form compounds. The atoms are held together by chemical bonds which can be either ionic or covalent. This quiz is all about covalent bonding. The three covalently bonded compounds that you need to know about in order to pass your exams are water, carbon dioxide and chlorine gas.

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When covalent chemical bonding occurs, atoms of the elements involved share electrons. Electrons are shared in pairs and atoms can share more than one pair of electrons. When an atom has shared the exact number of electrons it requires, it will not be able to share with any other atoms. No electrons are lost or gained therefore covalent compounds do not contain ions, they are made up from molecules. This is very different to ionic compounds which are giant structures of ions.

Some molecules are very simple and consist of only two atoms, like the oxygen that we breathe. Others are incredibly large and complex for example, a single strand of human DNA is made up from around 200 billion atoms, all covalently bonded.

It is essential for the exam that you know the about atoms, molecules, elements and compounds. A lot of students are not sure how these are all related.

Have a go at this quiz and see how well you understand covalent bonding.

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1. Which of the following is not true about the compound carbon disulfide?
[ ] It is made from molecules
[ ] It is ionically bonded
[ ] It is covalently bonded
[ ] There are twice as many sulfur atoms as carbon atoms
2. What is a single covalent bond?
[ ] One pair of shared electrons
[ ] Two pairs of shared electrons
[ ] One electron shared between two atoms
[ ] Four electrons shared between two atoms
3. Which of the following would have covalent bonding?
[ ] A compound made from metals
[ ] A compound made from non-metals
[ ] An element made from metals
[ ] None of the above
4. Which of the following could have covalent bonding?
[ ] An alloy
[ ] Atoms of a metal
[ ] Atoms of a non-metal
[ ] Molecules of a non-metal
5. How is a single covalent bond conveniently represented?
[ ] Two dots side by side
[ ] A short horizontal line between the symbols of the elements involved
[ ] A dot followed by a dash followed by a dot
[ ] A semi colon
6. Which of the following represents a molecule of carbon dioxide?
[ ] O=O=C
[ ] C=O=O
[ ] O=C=O
[ ] C=O=C
7. Why is the bonding in chlorine gas covalent?
[ ] Chlorine gas is made from molecules
[ ] Chlorine is an element
[ ] Chlorine is a halogen
[ ] Chlorine is a non-metal
8. Chlorine has seven electrons in its outer energy level (shell). Six of these are arranged in pairs with one on its own. How many covalent bonds can it form?
[ ] One
[ ] Two
[ ] Three
[ ] Seven
9. Is salt covalently bonded?
[ ] Yes, because it is made from crystals
[ ] Yes, because it dissolves in water
[ ] No, because it is made from a metal joined to a non-metal
[ ] No, because it can be obtained from the ground
10. Which of the following word equations correctly represents a reaction in which covalent bonding occurs?
[ ] Hydrogen + oxygen → water
[ ] Carbon + dioxide → carbon dioxide
[ ] Sulfuric acid + zinc → hydrogen + zinc sulfate
[ ] Chlorine + chlorine → dichlorine
GCSE Science Quiz - Chemistry - Covalent Bonding (AQA) (Answers)
1. Which of the following is not true about the compound carbon disulfide?
[ ] It is made from molecules
[x] It is ionically bonded
[ ] It is covalently bonded
[ ] There are twice as many sulfur atoms as carbon atoms
You may never have heard of this compound but that doesn't matter. The name tells you enough to answer the question
2. What is a single covalent bond?
[x] One pair of shared electrons
[ ] Two pairs of shared electrons
[ ] One electron shared between two atoms
[ ] Four electrons shared between two atoms
The second option describes a double covalent bond
3. Which of the following would have covalent bonding?
[ ] A compound made from metals
[x] A compound made from non-metals
[ ] An element made from metals
[ ] None of the above
Compounds of non-metals are always covalently bonded
4. Which of the following could have covalent bonding?
[ ] An alloy
[ ] Atoms of a metal
[ ] Atoms of a non-metal
[x] Molecules of a non-metal
Only molecules have covalent bonding which immediately rules out the other answers
5. How is a single covalent bond conveniently represented?
[ ] Two dots side by side
[x] A short horizontal line between the symbols of the elements involved
[ ] A dot followed by a dash followed by a dot
[ ] A semi colon
A double covalent bond looks like an equals sign and a triple covalent bond is like an equals sign with an extra line underneath (or above!) it
6. Which of the following represents a molecule of carbon dioxide?
[ ] O=O=C
[ ] C=O=O
[x] O=C=O
[ ] C=O=C
Carbon dioxide is a linear molecule - all 3 atoms are in a line, with carbon in the middle
7. Why is the bonding in chlorine gas covalent?
[ ] Chlorine gas is made from molecules
[ ] Chlorine is an element
[ ] Chlorine is a halogen
[x] Chlorine is a non-metal
All of the statements about chlorine are true. You may have chosen option 1 as you know molecules are always covalently bonded but that doesn't answer the question. The only option that answers 'why' is the fact that it is a non-metal
8. Chlorine has seven electrons in its outer energy level (shell). Six of these are arranged in pairs with one on its own. How many covalent bonds can it form?
[x] One
[ ] Two
[ ] Three
[ ] Seven
Only electrons that are not already part of a pair can be shared
9. Is salt covalently bonded?
[ ] Yes, because it is made from crystals
[ ] Yes, because it dissolves in water
[x] No, because it is made from a metal joined to a non-metal
[ ] No, because it can be obtained from the ground
To answer correctly without guessing you need to know that salt is sodium chloride. Sodium is a metal so it can't possibly be covalently bonded
10. Which of the following word equations correctly represents a reaction in which covalent bonding occurs?
[x] Hydrogen + oxygen → water
[ ] Carbon + dioxide → carbon dioxide
[ ] Sulfuric acid + zinc → hydrogen + zinc sulfate
[ ] Chlorine + chlorine → dichlorine
Only the first and the third word equations are correct and since the third one involves a metal, it must have ionic bonding