Molecular Geometry and VSEPR

Ideal Geometry

The central atom has no lone electron pairs.

AX₂

Linear, bond angle 180°

AX₃

Trigonal planar, bond angle 120°

AX₄

Tetrahedron, bond angle 109.5°

AX₅

Trigonal Bipyramid, bond angle 90°, 120°

AX₆

Octahedron, bond angle 90°

VSEPR Theory

Valence Shell Electron Pair Repulsion Theory:

-Double or single bonds can be treated like single bonds.

-If a molecule has resonance structures, VSEPR can be applied to any one of them.

-Lone pairs of electrons repel atoms more than bonding pairs do. Therefore, lone pairs take up more space than atoms.

AX₃E

Trigonal Pyramid geometry, tetrahedral arrangement of electron pairs, bond angle 107.3°

AXE₃

Linear, bond angle 180°

AX₂E₂

Bent geometry, tetrahedral arrangement of electron pairs, bond angle 104.5°

AX₂E

Bent geometry, trigonal planar electron pair configuration.

AX₄E

Seesaw/distorted tetrahedron geometry, trigonal bipyramidal electron pair configuration.

AX₃E₂

T-shaped geometry, trigonal bipyramidal electron pair configuration.

AX₂E₃

Linear geometry, trigonal bipyramidal electron pair configuration.

AX₅E

Square pyramidal geometry, octahedral electron pair configuration.

AX₄E₂

Square planar geometry, octahedral electron pair configuration.