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Shape Lab VSEPR and the 3D shapes of molecules
About this activityChemistry · Grades 9–12 · About 50 minutes

Learning outcomes

Students will be able to:

  • Explain VSEPR theory: electron groups around a central atom repel and spread as far apart as possible.
  • Identify the five electron geometries and their bond angles (180°, 120°, 109.5°, 90°/120°, 90°).
  • Explain how lone pairs change molecular shape and squeeze bond angles, and distinguish electron geometry from molecular shape.
  • Predict the shape of a molecule from its Lewis structure, and use shape to decide whether a molecule is polar.

Standards alignment

  • HS-PS1-1 NGSS: Use the periodic table as a model to predict properties of elements based on the patterns of electrons in the outermost energy level.
  • HS-PS1-3 NGSS: Gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
  • SEP 2 NGSS Science and Engineering Practice: develop and use models.

Includes

Four stages: a 3D balloon model of the five electron geometries, lone-pair squeeze sequences, ten build-it molecules from Lewis structures (two challenge molecules), and six polarity checks with bond dipole arrows; and a printable lab worksheet. A teacher answer key is available from Logical Home Schooling.

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