Intro To Organic Chemistry Flashcards
(29 cards)
How can C form 4 bonds when it only has 2 unpaired electrons?
When excited, one 2s electron can be promoted to the vacant 2p orbital, resulting in four unpaired electrons in excited state
What is hybridisation?
Hybridisation refers to the mixing of atomic orbitals in various combinations to give a set of hybrid orbitals of equivalent energy for covalent bonding with other atoms
What are the rules of hybridisation?
- number of atomic orbitals used in hybridisation = number of hybrid orbitals formed
- hybrid orbitals of the same type are equivalent and degenerate
- Only apply to central atoms
What is sp3 hybridisation?
- One s and 3 p valence orbital
- 25% s character and 75% p character
- single bond
- tetrahedral
What is sp2 hybridisation?
- One s and 2 p valence orbital
- 33.3% s character and 66/7% p character
- double bond
- trigonal planar
What is sp hybridisation?
- One s and one p valence orbital
- 50% s character and 50% p character
- triple bond
- linear
How to use hybridisation to explain the difference in bond length of why ethane bond length greater than ethene?
- Hybridisation of C in ethane is sp3 while ethene is sp2
- sp2-hybridised orbital has greater s character than sp3 hybridised orbital and is closer to nucleus and smaller in size
- 2sp2-1s overlap is shorter in length than 2sp3-1s overlap
What is a saturated molecule?
Only single bonds
What is unsaturated molecule?
Multiple bonds
What are aliphatic compounds?
No aromatic ring
What are aromatic compounds?
Compounds with delocalised pi electron system
What do members of homologous series have?
- Same functional group thus similar chemical properties
- Have general formula
What is 1 to 10 for root name?
1: meth-
2: eth-
3: prop-
4: but-
5: pent-
6: hex-
7: hept-
8: oct-
9: non-
10: dec-
What is homolytic fission?
Covalent bond broken such that each bonding atom takes one bonding electron, giving rise to free radicals
What is heterolytic fission?
Covalent bond broken such that one of bonding atom takes both bonding electrons while the remaining becomes a cation
What does full arrow represent?
Movement of a pair of electron
What does half arrow represent?
Movement of one electron
What are isomers?
Compounds with same molecular formula but different arrangement of atoms in 3-dimensional space
What are constitutional isomers?
Compounds with same molecular formula but different structural formula
What are stereoisomers?
Same molecular and structural formula but differ in spatial arrangement of atoms
When can cis-trans isomerism be exhibited by a molecule?
- restricted rotation about a covalent bond
- two different groups/atoms attached to each carbon of the bond of restricted rotation
What are enantiomers?
Stereoisomers with non-superimposable mirror images
What is a chiral carbon centre?
4 different groups attach to a carbon
Do enantiomers have similar physical properties?
Yes, except their effect on plane-polarised light
