Uploaded August 2025 | Updated September 2026, 2 weeks ago
Molecular Geometry When Central Atom has One or More Lone Pairs
Dr. DeBacco
Lone Pairs Impact on Geometry
Lone pairs affect geometry because they repel bonding pairs more strongly, altering bond angles and overall shape.
Step-by-Step Guide Using VSEPR Theory
Draw the Lewis Structure
Count valence electrons.
Place lone pairs and bonds around the central atom.
Count Electron Groups Around the Central Atom
Each bond (single, double, triple) counts as one group.
Each lone pair counts as one group.
Determine Electron Geometry
Based on total electron groups:
Determine Molecular Geometry
Now subtract lone pairs and look at the positions of atoms only:
Adjust Bond Angles
Lone pairs push bonding pairs closer together.
Typical bond angles shrink:
Tetrahedral: 109.5° → Trigonal pyramidal: ~107° → Bent: ~104.5°
Link to Lecture Slides: drive.google.com/file/d/1ifFAf5d0csoE50rPiZ5dE72CXiSnAbi6/view?usp=drive_link
*Due to the description character limit the full work cited for "Molecular Geometry When Central Atom has One or More Lone Pairs" can be viewed at... docs.google.com/document/d/1wrJzprnh3fNKK-SLJjib3YNuwLcVt-IY/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
Molecular Geometry When Central Atom has One or More Lone Pairs
Dr. DeBacco
Lone Pairs Impact on Geometry
Lone pairs affect geometry because they repel bonding pairs more strongly, altering bond angles and overall shape.
Step-by-Step Guide Using VSEPR Theory
Draw the Lewis Structure
Count valence electrons.
Place lone pairs and bonds around the central atom.
Count Electron Groups Around the Central Atom
Each bond (single, double, triple) counts as one group.
Each lone pair counts as one group.
Determine Electron Geometry
Based on total electron groups:
Determine Molecular Geometry
Now subtract lone pairs and look at the positions of atoms only:
Adjust Bond Angles
Lone pairs push bonding pairs closer together.
Typical bond angles shrink:
Tetrahedral: 109.5° → Trigonal pyramidal: ~107° → Bent: ~104.5°
Link to Lecture Slides: drive.google.com/file/d/1ifFAf5d0csoE50rPiZ5dE72CXiSnAbi6/view?usp=drive_link
*Due to the description character limit the full work cited for "Molecular Geometry When Central Atom has One or More Lone Pairs" can be viewed at... docs.google.com/document/d/1wrJzprnh3fNKK-SLJjib3YNuwLcVt-IY/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
