Unit 1 Flashcards
1
Q
Hybridization for linear
A
Sp
2
Q
Hybridization for bent
A
NONE!
3
Q
Sigma bond
A
- overlap of s orbitals that lies directly on the axis.
- headon overlap
4
Q
Pi bond
A
- overlap of p orbitals
- that run parallel to each other
- touch on their sides - bad overlap/weaker bond
5
Q
Why is sp2 orbital lower in energy than a pure p orbitals
A
More s character, so lower energy
6
Q
How to you define a bonding vs anti bonding
A
Bonding:
- constructive interaction
- phases match of orbitals
-
7
Q
Bond order equation
A
(Bonding electrons)-(antibonding electrons) /2
Higher the bond order, the stronger the bond.
8
Q
Hybridization for trigonal pyramidal
A
Sp3
9
Q
Hybridization for tetrahedral
A
Sp3
10
Q
What type of interference causes bonding orbital?
A
- constructive
11
Q
What type of interaction causes anti bonding orbitals?
A
- destructive
- node is an area where the probability of finding an electron between the 2 atoms drops to 0
12
Q
Relationship between energy of bonding vs antibonding orbital
A
- Bonding orbital is typically lower in energy than an anti bonding orbital
13
Q
Resonance structure
A
- shows electron delocalisation by shifting pi bonds and lone pairs
14
Q
Factors to determine strength of resonance structures
A
15
Q
Conjugation
A
- shows electron delocalization by overlapping p orbitals
16
Q
Criteria for conjugated systems
A
- compose of 3 or more p orbitals
- P orbitals must be on adjacent atoms
- P orbitals must be aligned, pi bond alignment
17
Q
How do you know if an electron is delocalised
A
- when a lone pair is located in a p orbital
- a lone pair that is NEXT to a pi bond, it can delocalize
- a lone pair is trapped on an atom that already has a pi bond.
18
Q
Criteria for aromatic system
A
- requires a fully conjugated cyclic system, (so looking for rings and lone pairs)
- every atom in the ring possesses a p orbital
- and all p orbitals are aligned, ring is flat
- Huckel 4n+2 rule- aromatic systems contain a multiple of 4n+2 pi electrons where n is any positive integer
19
Q
Empirical resonance energy
A
- a value for the stabilization due to electron delocalization
20
Q
Degenerate orbitals
A
- orbitals of equal energy
21
Q
Antiaromatic systems
A
- a cyclic, conjugated system with a planar ring
- but contains 4n pi electrons
- and are VERY unstable and reactive
22
Q
Bronsted Lowry acid
A
- proton donator
23
Q
Bronstead Lowry Base
A
Proton acceptor
24
Q
How do you classify a conjugate acid
A
- the molecule holding onto the proton donated by the acid
25
How do you classify a conjugate base
- the acid without the proton now
26
Give the characteristics of strong acids’ conjugate bases
- weak
- stable
- low energy
27
Strong acid and pKa value correlation
- strong acid = lower (more negative) pKa value
28
Newman projections
- a way to show 3d structure and define conformation, the orientation of substituents
29
Staggered vs eclipse
- staggered: dihedral angle 60, spaced low energy
- eclipsed: dihedral angle: 0, packed together, high energy
30
Staggered confirmation substituent relationships
- anti - dihedral angle is 180
- low energy position for 2 groups
Gauche - 2 groups are awkward neighbors
- higher energy position (steric interaction)
- dihedral angle is 60
31
Wedge
- in front (pointing at u)
32
Dashed
- back facing away from you
33
DEGREES OF UNSATURATION
- NUMBER RINGS AND OR PI BOND
34
Formula of DOU
(2xC) + 2-H+N-X)/2
X is halogen
35
Stereoisomers
- Sam connections between atoms but different positions in space
36
Trans
- one group away from you, one group facing towards you
37
Cis
- both groups pointing in the same direction (eg towards you, or away from you)
38
How to draw equatorial substituents
- match bond angle to the bond that is one bond over the carbon you’re drawing the bond on
39
Ring strain
- causes an increase in energy of the molecule
40
Angle strain
- deviation form a 109/5 degree bond angle
- main culprit for small rings being so high in energy
41
Torsional strain
- due to a rigid structure, no flexibility
- locked in a high energy confirmation
42
Transannular strain
Atoms across the ring clashing
Occurs in rings c7-c12
43
Isopropyl
- 1-methylethyl
44
Tert-butyl
- 1,1-dimethylethyl
45
Diasteromers
- stereoisomers that are not mirror images
- have different chemical properties
46
Achiral molecule
- has an internal mirror plane has at least one conformation that is symmetric
- optically inactive
47
Meso molecules
- has Stereocentres and internal mirror plane, and has at least one conformation that is symmetric
- optically inactive
48
What measures the optical activity of a molecule
- a polarizer
49
Observed rotation equation
Alpha= (a)D^25 x L x Ctot X EE
50
Enantiomeric excess (EE)
- a way to describe UNEQUAL mixtures of enantiomers
- % of major - % minor enantiomer
- give percentage of the sample that is detected in an experiment
