Chapter 6 - Shapes Flashcards
Describe what electron pair repulsion theory is.
+Electron pairs surrounding central atom determine the molecule/ion shape
+Pairs repel each other so they’re arranged as far apart as possible
+Different numbers of electron pairs = different shape
What dictates/predicts the shape of a molecule or ion?
Electron pair repulsion theory
+The number of electron pairs around the central atom
+Whether these are bonded/lone pairs
Describe what each says about the 3D representations
Straight line
Solid wedge
Dotted wedge
Straight line - in the plane
Solid wedge - out of a plane
Dotted line- into plane
Why do you lone pairs repel stronger than bonded pairs?
+ They are closer to the central atom
+ They occupy more space
How much is a bond angle reduced per loan pair?
2.5°
State the shape and bond angles for:
- CH4
- NH3
- H2O
CH4 — tetrahedral — 109.5
NH3 — pyramidal — 107
H2O — non linear — 104.5
What is the shape and bond angle of the molecule?
- 2 bonded pairs
- no lone pairs
Linear 180°
What is the shape and bond angle of the molecule?
- 2 bonded pairs
- 1 lone pair
Nonlinear 117.5°
What is the shape and bone angle of the molecule?
- 2 bonded pairs
- 2 lone pairs
Nonlinear 104.5°
What is the shape and bond angle of the molecule?
- 5 bonded pairs
- no lone pairs
Triganol bypyramidal
90° perpendicular
120° in plane
What is the shape and bond angle of the molecule?
- 3 electron pairs
- no lone pairs
Trigonal planar 120°
What is the shape and bond angle of the molecule?
- 6 bonded pairs
- 0 lone pairs
Octahedral 90°
What is the shape and bond angle of the molecule?
- 3 bonded pairs
- 1 lone pair
Trigonal pyramid 107°
What is the shape and bond angle of the molecule?
- 4 bonded electron pairs
- No lone pairs
Tetrahedral 109.5°
