IB Chemistry HL 2.2.13 Hl Expanded Octets Questions

Identify central atoms that exceed an octet, draw complete Lewis formulas and use trigonal-bipyramidal or octahedral electron domains to deduce molecular shapes.

Exam points

Identify period-three or heavier central atoms that can accommodate five or six electron domains and an expanded octet.
Draw complete Lewis electron-dot structures for expanded-octet species, including central-atom bonds, lone pairs and charge where required.
Apply VSEPR to five- and six-domain species to deduce electron-domain geometry, molecular shape and characteristic bond angles.

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Study 2.2.13 (HL)—Expanded octets conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 3]

Phosphoryl chloride, $\mathrm{POCl}_{3}$ , is a dehydrating agent.

(a)

$\mathrm{POCl}_{3}$ can be prepared by the reaction of phosphorus pentachloride, $\mathrm{PCl}_{5}$ , with tetraphosphorus decaoxide, $\mathrm{P}_{4} \mathrm{O}_{10}$ .

[ 3 ]

(i)

Deduce the Lewis (electron dot) structure of $\mathrm{PCl}_{5}$ .

[ 1 ]

(ii)

Predict the shape of this molecule, using the valence shell electron pair repulsion theory (VSEPR).

[ 1 ]

$\ce{PCl5}$ has a trigonal bipyramidal shape.

(iii)

Identify all the different bond angles in $\mathrm{PCl}_{5}$ .

[ 1 ]

$120^{\circ}$ and $90^{\circ}/180^{\circ}$ ;

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IB Chemistry HL 2.2.13 Hl Expanded Octets Questions question 1

Question (a)

Question (i)

Question (ii)

Question (iii)