Calcium chloride
3 marks · EasyState the formula of the calcium ion formed in calcium chloride.
State the formula of the chloride ion formed in calcium chloride.
Draw a dot-and-cross diagram to show the ions in calcium chloride.
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) Ca^{2+}
(b) Cl^{-}
(c) — · must show Ca ion with 8 outer electrons (2+ charge, brackets), Two Cl ions with 8 outer electrons (1- charge, each with one extra electron), Differentiate Ca and Cl electrons (e.g., dot and cross)
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Marking points
B1 (a) · 1 mark · Correctly states Ca^{2+} as the formula of the calcium ion.
B1 (b) · 1 mark · Correctly states Cl^{-} as the formula of the chloride ion.
B1 (c) · 1 mark · Correct diagram showing Ca^{2+} ion with two empty outer electrons (or full shell with brackets and 2+), two Cl^{-} ions each with correct number of outer electrons, showing the transfer from Ca to two Cl, using dots and crosses for different atoms, correct charges.
Worked solution
a) The formula of the calcium ion is . b) The formula of the chloride ion is . c) The dot-and-cross diagram shows one Ca ion with a full octet (eight outer electrons, using one symbol, e.g., dots) and a 2+ charge in a bracket, and two Cl ions, each with eight electrons in their outer shell (typically drawn with seven crosses and one dot) and a 1- charge each, with all ions in brackets. Each Cl ion gains one electron from the Ca atom, shown with the dot as the additional electron.