Vsepr theory test with mark scheme, AP Chemistry (PDF)

Quick answer: A Lewis structure shows how valence electrons are shared as bonds and lone pairs, and formal charges help choose the best one. This AP Chemistry test on vsepr theory has 8 questions worth 20 marks, to do in 40 minutes: Lewis structure of PCl₃, formal charges in carbon monoxide and resonance in carbonate. The mark scheme is on a separate page; free printable PDF.

Vsepr theory test with answers for AP Chemistry (free PDF download)

This AP Chemistry test on vsepr theory test works like a real class test. The mark scheme is on a separate page, so revise with the lesson first.

This test covers Lewis structures, formal charge, resonance, shapes, polarity and hybridization. It has 8 questions worth 20 marks. No hints are given, and a periodic table is allowed.

Level: AP Chemistry · Curriculum: AP Chem Unit 2

Contents

Vsepr theory test: the test questions

Time: 40 minutes · 8 questions · Total: 20 marks · Calculator allowed

Question 1 Lewis structure of PCl₃ (3 marks)

Phosphorus trichloride has 26 valence electrons.

Describe its Lewis structure, including lone pairs. (1 mark)
State the molecular shape and the approximate bond angle. (1 mark)
State the hybridization of phosphorus. (1 mark)

Question 2 Formal charges in carbon monoxide (3 marks)

The Lewis structure of CO is C≡O with one lone pair on each atom.

Calculate the formal charge on C. (1 mark)
Calculate the formal charge on O. (1 mark)
Explain why this structure is still the best one. (1 mark)

Question 3 Resonance in carbonate (2 marks)

State how many resonance structures carbonate has. (1 mark)
Calculate the average C–O bond order. (1 mark)

Question 4 Sulfur tetrafluoride (3 marks)

SF₄ has 34 valence electrons.

State the number of lone pairs on sulfur. (1 mark)
Name the electron geometry and the molecular shape. (1 mark)
State whether the molecule is polar and give a reason. (1 mark)

Question 5 Methanal (3 marks)

The figure shows methanal.

Count the σ and π bonds. (1 mark)
State the hybridization of carbon. (1 mark)
Predict the H–C–H angle compared with 120° and give a reason. (1 mark)

Methanal, CH₂O.

Question 6 Polarity of CF₄ and CHF₃ (2 marks)

Explain why CF₄ is nonpolar but CHF₃ is polar. (2 marks)

Question 7 Bond strength (2 marks)

The C–O bond length is 143 pm in methanol and 120 pm in methanal.

Identify the stronger bond. (1 mark)
Explain the difference in length. (1 mark)

Question 8 Spot the error (2 marks)

A student states that ammonia is planar with 120° angles because nitrogen forms three bonds. Identify the error and give the correct shape and angle. (2 marks)