Chem Ch7 : Molecular Geometry and Bonding Theories

• What is the geometry and bond angle of a molecule with two electron domains?

• Linear geometry; bond angle of 180°. All atoms lie in a straight line.

• Describe trigonal planar geometry and its bond angles.

• Trigonal planar geometry has three atoms arranged in a plane with bond angles of 120°. All positions are equivalent.

• What is the shape and bond angle of tetrahedral molecules?

• Tetrahedral shape is a pyramid with trigonal faces (4 sides), bond angles are approximately 109.5°, and all four positions are equivalent.

• Explain trigonal bipyramidal geometry.

• Trigonal bipyramidal geometry consists of two trigonal pyramids sharing one face (6 positions). It has axial and equatorial positions with bond angles of 90°, 120°, and 180°.

• What are the features of octahedral molecular geometry?

• Octahedral geometry is made of two square pyramids sharing one face (8-sided). All six positions are equivalent with bond angles of 90° and 180°.

• According to VSEPR theory, why do molecules assume specific shapes?

• Because valence electron pairs repel each other and arrange themselves as far apart as possible to minimize repulsion.

• What counts as an electron domain in VSEPR theory?

• Electron domains include lone pairs or bonding pairs; single, double, and triple bonds are all counted as one electron domain.

• What are the general steps to predict molecular geometry using VSEPR theory?

• Step 1: Draw Lewis structure; Step 2: Count electron domains; Step 3: Determine electron-domain geometry.