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IB DP Chemistry: SL復習筆記4.2.3 Predicting Molecular Shapes

Category: IB課程, 教材筆記, 福利干貨 Date: 2022年8月4日上午11:36

Before you predict the shape of any molecule work out the Lewis structure to determine the number of bonding and lone pairs
Apply the VSEPR rules and you should be successful in deducing the correct shape and bond angle

Predict the domain geometry, shape and bond angle in the following molecules or ions:

Answers:

Answer 1:?The total number of valence electrons in H₂S is = 1 + 1 + 6 = 8, so there are four pairs of electrons around S

Hydrogen only forms one bond, so there are two bonding pairs and two lone pairs:

4.1.9-worked-example-Answer-1

Answer 2:?The total number of valence electrons in NH₂Cl is = 5 + 1 + 1 + 7 = 14

4.1.9-Worked-Example-Answer-2

Answer 3:?The total number of valence electrons in NO₂⁺= 5 + 6 + 6 -1 = 16? (subtracting one for the positive charge)

4.1.9-Worked-example-Answer-3

Answer 4:?The total number of valence electrons in ClF₂⁺= 7 + 7 + 7 -1 = 20? (subtracting one for the positive charge)

4.1.9-Worked-Example-Answer-4

For Standard Level Chemistry you are only required to know the shape of molecules up to four electron domains.

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