Download - Molecular geometry
No heavy math includedNo heavy math included
Molecular Molecular GeometryGeometry
Shapes of Molecules Molecular Structure or Molecular Geometry
- is the three-dimensional arrangement of the atoms that constitute a molecule. It determines several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism, and biological activity.
- the chemical formula has no direct relationship with the shape of the molecule.
Shapes of Molecules Molecular Structure or Molecular Geometry
- the three-dimensional shapes of molecules can be predicted by their Lewis structures.
- Valence-shell electron pair repulsion (VSEPR) model or electron domain (ED) model: Used in predicting the shapes. The electron pairs occupies a certain domain. They move as far as possible. Lone pairs occupies more domains contributing largely to the repulsion and shape.
Terms and Definition Bonding Pairs (AX)– electron pairs that are involved in
the bonding.
Lone Pairs (E)– electrons that are not involved in the bonding. They tend to occupy a larger domain.
Electron Domains – total number of pairs found in the molecule that contribute to its shape.
Linear
• Bonding Pairs: 2• Lone Pairs: 0• Electron Domains: 2• Bond angle: 180°• Example: CO2
Image:
Trigonal Planar
• Bonding Pairs: 3• Lone Pairs: 0• Electron Domains: 3• Bond angle: 120°• Example: BF3
Image:
Bent or Angular
• Bonding Pairs: 2• Lone Pairs: 1• Electron Domains: 3• Bond angle: 120° (119°)• Example: SO2
Image:
Tetrahedral
• Bonding Pairs: 4• Lone Pairs: 0• Electron Domains: 4• Bond angle: 109.5°• Example: CH4
Image:
Trigonal Pyramidal
• Bonding Pairs: 3• Lone Pairs: 1• Electron Domains: 4• Bond angle: 109.5° (107.5°)• Example: NH3
Image:
Bent or Angular (Ver.2)
• Bonding Pairs: 2• Lone Pairs: 2• Electron Domains: 4• Bond angle: 109.5° (104.5°)• Example: H2O
Image:
Trigonal Bipyramidal
• Bonding Pairs: 5• Lone Pairs: 0• Electron Domains: 5• Bond angle: 90°, 120°• Example: PCl5
Image:
Seesaw
• Bonding Pairs: 4• Lone Pairs: 1• Electron Domains: 5• Bond angle: 180°, 120° (173.1°,
101.6°)• Example: SF4
Image:
T-shaped
• Bonding Pairs: 3• Lone Pairs: 2• Electron Domains: 5• Bond angle: 90°, 180° (87.5°, < 180°)• Example: ClF3
Image:
Linear (Multiple Lone Pairs)
• Bonding Pairs: 2• Lone Pairs: 3• Electron Domains: 5• Bond angle: 180°• Example: XeF2
Image:
Octahedral
• Bonding Pairs: 6• Lone Pairs: 0• Electron Domains: 6• Bond angle: 90°• Example: SF6
Image:
Square Pyramidal
• Bonding Pairs: 5• Lone Pairs: 1• Electron Domains: 6• Bond angle: 90° (84.8°)• Example: BrF5
Image:
Square Planar
• Bonding Pairs: 5• Lone Pairs: 1• Electron Domains: 6• Bond angle: 90°• Example: XeF4
Image:
Pentagonal Bipyramidal
• Bonding Pairs: 7• Lone Pairs: 0• Electron Domains: 7• Bond angle: 90°, 72°• Example: IF7
Image: