IB Chemistry SL R3.3 Electron sharing reactions questions

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Question 1

Multiple choiceMedium1 mark

Four oxygen-containing species are compared: OH, OH⁻, H₂O and H₃O⁺. Which analysis correctly identifies a radical and predicts its reactivity from its electron arrangement?

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Answer: C. Neutral OH has 6 + 1 = 7 valence electrons. Its Lewis representation has one unpaired electron, so it is a radical and is expected to be highly reactive.

A: omits the extra electron from the negative charge; OH⁻ has 8 valence electrons, all paired. B: counts H₂O correctly but mistakes paired lone-pair electrons for an unpaired electron. D: fails to subtract one electron for the positive charge; H₃O⁺ has 8 valence electrons, all paired.

Remember: add an electron for a negative charge and subtract one for a positive charge.

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