Lectures One and Two Flashcards
Molecular Shapes (Tetrahedral)
- Four charge clouds
- 109.5 degrees
Molecular Shapes (Trigonal Planar)
- Three charge clouds
- 120 degrees
Molecular Shapes (Linear)
- Two charge clouds
- 180 degrees
sp (3)
- ALKANES
- made from mixing of 2s and 2p electrons
- tetrahedral arrangement (109.5 degrees)
- 4 bonds of the same energy
- form single sigma bonds
sp (2)
- ALKENES
- made from mixing of one electron from 2s
and 2 electrons from 2 p - trigonal planar arrangement (120 degrees)
- form double bonds, one sigma and one pi bond
sp
- ALKYNES
- made from mixing one 2p electron with the 2s electrons (2)
- linear arrangement (180 degrees)
- forms triple bonds, 2 pi bonds and one sigma bond
Hybridization Influences….
- Bond Angle
- Bond Rotation
- Bond Length
- Bond Strength
How does hybridization influence bond length?
The s orbital is closest to the nucleus making it shorter than the p orbital. Since sp (3) has the most “p-character’ it’ll be the longest and with sp having the bigger ratio of s to p it will be the shortest.
Hence:
sp (3) > sp (2) > sp
Hybridization Categories
sp (3)- single bonds, freely rotate which leads to different conformation (Alkanes)
sp (2)- double bonds cannot rotate (rigid) gives different geometry (Alkenes)
sp- rigid, cannot rotate (Alkynes)
(image on slide 33)
Bond Polarity (Electronegativity Trend)
- increases across the period
- decreases down the group
Classification of Hydrocarbons
- Cycloalkane: carbons form a ring (single bonds only)
- Cycloalkene: double bond in ring
- Aromatic: contains a benzene ring
Cycloalkane formula
CnH2n
Alkane formula
CnH2n+2
Alkene formula
CnH2n
Alkyne formula
CnH2n-2
