Calcium chloride
1 mark · EasyDraw a dot-and-cross diagram to represent the chloride ion in calcium chloride.
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Must show: Eight outer electrons for Cl^-, Extra electron shown with different symbol (dots/crosses), A bracket with negative charge
Common mistakes: Seven electrons drawn instead of eight; No bracket or charge shown
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Marking points
B1 · 1 mark · Correct dot-and-cross diagram for Cl^-: eight outer electrons, at least one from Ca (different symbol), square bracket and - charge shown.
Worked solution
Diagram should show a Cl atom in square brackets with 8 electrons (7 of one type, 1 of another), and a negative sign outside.