Electron-Pair Geometries

Trigonal Planar Electron-Pair Geometry

• There are two molecular geometries (shapes):
• Trigonal Planar: if all the electron pairs are bonding
• Bent: if one of the electron pairs is a lone pair
• Bond angle: 120°

Trigonal Planar E-P Geometry

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• Caption: Trigonal Planar
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• Caption: Bent

Tetrahedral Electron-Pair Geometry

• There are three molecular geometries:
• Tetrahedral: if all are bonding electron pairs
• Trigonal pyramidal: if one is a nonbonding electron pair
• Bent: if there are two nonbonding electron pairs
• Bond Angle: 109.5°
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Trigonal Bipyramidal E-P Geometry

• There are four distinct molecular geometries:
• Trigonal bipyramidal: if all are bonding electron pairs
• Bond angle: 90°, 120°, or 190°
• Seesaw: if one is a nonbonding electron pair
• T-Shaped: if there are two nonbonding electron pairs
• Linear: if there are three nonbonding electron pairs
• ​​​​​​​Bond angle: 180°
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Octahedral Electron-Pair Geometry

• All positions are equivalent in the octahedral electron-pair geometry
• There are three molecular geometries:
• Octahedral: if all bonding electron pairs
• Square pyramidal: if one is a nonbonding electron pair
• Square Planar: if there are two nonbonding electron pairs
• Bond angle: 90°
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Some Molecular Geometries