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CAIE A Level Chemistry 9701 · The Periodic Table: chemical periodicity

The Periodic Table: chemical periodicity: describe question

Describe7 marksChallenge

A student reacts the period 3 elements magnesium and silicon separately with steam, and separately with chlorine gas.

(a) Write the equation for the reaction of magnesium with steam, and state two observations that would be made.

(b) Write the equation for the reaction of silicon with chlorine, and state the oxidation number of silicon in the product.

(c) Explain, in terms of the outer shell (valence shell) electrons of the elements, why the oxidation number of silicon in its chloride is different from the oxidation number of magnesium in its chloride.

(d) The student also reacts phosphorus with chlorine to form phosphorus(V) chloride. Write the equation for this reaction and state the oxidation number of phosphorus in the product.

0 words · 7 marks

No account needed for your first marks. Your answer is used only to mark it.

How this question is marked

7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.

Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.

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