What is a covalent bond?
3 marks · EasyA student claims: ‘All atoms in a covalent bond must supply one electron to the shared pair.’
Is this statement always correct? Give a reason for your answer.
State what a shared pair of electrons is called.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) No, sometimes both electrons in a shared pair can come from the same atom. This is known as a dative or coordinate bond. · must show Correctly states 'No', Explains dative/coordinate bonding as exception
(b) Covalent bond · must show States 'covalent bond'
Also accept: Dative bond mentioned as exception
Common mistakes: Agreeing without reason
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Marking points
M1 (a) · 1 mark · States the claim is not always correct (explicit 'No').
A1 (a) · 1 mark · Gives a correct reason: sometimes both electrons come from the same atom (dative/coordinate bond).
B1 (b) · 1 mark · States that a shared pair of electrons is called a covalent bond.
Worked solution
a) No, this is not always correct. Sometimes both electrons in the shared pair are donated by a single atom (as in a dative/coordinate bond).
b) A shared pair of electrons is called a covalent bond.