What is a covalent bond?
3 marks · EasyChlorine exists as diatomic molecules ( Cl2 ).
Draw a dot-and-cross diagram to show the covalent bonding in a molecule of chlorine (Cl2).
How many electrons are shared between the two chlorine atoms?
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) Dot-and-cross diagram for Cl2 showing a single shared pair (bond) between two Cl atoms. Each Cl has 3 lone pairs and 1 bonding pair in outer shell. Dots from one, crosses from the other. · must show Each Cl atom has 7 outer electrons, A shared pair/bond between the Cl atoms, Outer shells only shown, dots for one atom, crosses for the other, Lone pairs and bonding pair shown correctly
(b) 2 · must show 2 shared electrons
Common mistakes: Showing a single bond between Cl atoms; Incorrect electron count
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Marking points
B1 (a) · 1 mark · One mark for correct arrangement: each Cl atom shows 7 outer electrons, with a single shared pair (bond) between.
B2 (a) · 1 mark · Lone pairs shown correctly (3 on each Cl atom), using dots for one atom and crosses for the other.
B3 (b) · 1 mark · States 2 electrons are shared between the two atoms.
Worked solution
a) Each chlorine atom has 7 electrons in its outer shell. A single covalent bond forms when each atom shares 1 electron, forming a shared pair.
b) There are 2 electrons shared between the chlorine atoms.