VSEPR Flashcards
What is the Valence Shell Electron Pair Repulsion Theory?
- It is a way to predict covalent bonded 3D structures based on the fact that electron pairs/domains will want to be as far away from each other as possible
What does a Lewis Structure show?
- Shows atom to atom connectivity
- Shows distibution of valence electrons
What does a VSEPR Structure show?
- Translates Lewis into molecular geometry
- Helps predict the shape and bond angles of molecules
What does a wedge show?
Coming out of the page
What does a Hash show?
Going into the page
What does a line show?
In the same plane as the paper
What is an electron domain?
- Regions in space where valence electron density can be found
- Lone Pairs
- Bonds (a single, double, or triple bond all count as one domain)
What is an Electron-pair Geometry?
- Describes the arrangement of all electron pairs/domains around a central atom in 3D Space
- Includes bonds and lone pairs
What is a Molecular Geometry Shape?
- Describes the arrangement of bonding pairs/domains around a central atom in 3D space
- Shape the bonds make
If a central atom has only bonding domains…
Electron-pair geometry = molecular shape
If a central atom has both bonding domains and lone pairs…
Electron-pair geometry does not = molecular shape
What does the presence of lone pairs have on bond angles?
Decreases bond angles because lone pairs like to have more space
What are the characteristics of a 2-electron domain - Linear Electron-Pair geometry?
- All atoms lie in a straight line
- The bond angle between three atoms is 180 degrees
- No non-bonding electrons on the central atom
What are the characteristics of a 3-electron domain - Trigonal Planar Electron-Pair geometry?
- A central atom is surrounded by 3 atoms
- All atoms can lie in the same plane
- The bond angle is 120 degrees
(consider resonance)
What are the characteristics of a 3-electron domain - Trigonal Planar Electron-Pair geometry with a bent molecular shape?
- A central atom is bonded by 2 atoms and has 1 lone pair
- All atoms can lie in the same plane
- The bond angle are < 120 degrees
What are the characteristics of a 4 Electron Domain - Tetrahedral Electron-Pair geometry?
- A central atom is bonded to 4 atoms
- The bond angles are 109.5 degrees
What are the characteristics of a 4 Electron Domain - Tetrahedral Electron-Pair Geometry with a Trigonal Pyramidal Molecular Shape?
- A central atom is bonded to 3 atoms and has 1 lone pair
- The bond angles are <109.5 degrees