CHEM 261 Flashcards
(114 cards)
1
Q
How big is an Angstrom?
A
10^ -8 cm
2
Q
What are the 2 basic principles of chemistry?
A
a) Like Charges Repel
b) Atoms Want An Inert Gas Configuration
3
Q
What is Avogadro’s number?
A
6.022 e 23
4
Q
Isoelectronic meaning
A
Equal number of electrons
5
Q
What is a pure compound?
A
A compound with no change in physical properties upon further purification?
6
Q
4 Properties of Organic Compounds
A
- Non-polar
- Soluble in oil
- Low mp and bp
- Burn in O2
7
Q
STP Conditions
A
760 mmHg (1 atm)
0 degrees C (273 K)
8
Q
Degenerate Orbitals Have _________.
A
The same energy
9
Q
What is the Aufbau Principle?
A
Electrons fill the lowest energy orbitals first, with opposite spins
10
Q
What is the Pauli Exclusion Principle?
A
Max 2e- per orbital
11
Q
If an orbital contains an “s” component, it must be ____.
A
Sigma
12
Q
What type of orbital contains only “p” components?
A
Pi
13
Q
Is a bonding or antibonding orbital higher in energy?
A
Antibonding
14
Q
What is the ideal bond angle for a tetrahedral complex?
A
109 degrees
15
Q
What is the ideal bond angle of an sp2 hybridized bond?
A
120 degrees
16
Q
Do lone pairs or radicals count as an e- group for shape?
A
Yes
17
Q
What is the longest bond type?
A
X-H, C-C, C=X, C=C
18
Q
What does a bold wedge mean?
A
Towards you
19
Q
What does a dashed line mean?
A
Away from you
20
Q
What functional groups are in testosterone?
A
Methyl, methylene, ketone, alcohol
21
Q
What functional groups are in estradiol?
A
Methyl, methylene, phenol
22
Q
What must be considered to properly depict molecules?
A
Formal Charge
23
Q
What is the formula to calculate formal charge?
A
of protons in nucleus
- e- in inner shell (usually 2)
- unshared e- in outer shell
- 0.5 x shared e-
24
Q
Are resonance structures rapidly interconverting structures?
A
Nope
25
What is electronegativity?
An atoms desire for electrons
26
Order the 3 Intermolecular forces
Strongest
Hydrogen bonding
Dipole-dipole
London Dispersion Forces
Weakest
27
What is necessary for hydrogen bonding to occur?
A lone pair on the halogen electron acceptor (electronegative atom)
Hydrogen must be directly attached to halogen
28
What is the name for CHCl3
Chloroform
29
What is the name for CH2Cl2
Dichloromethane / methylene chloride
30
What is the name for CCl4
Carbon tetrachloride
31
What is boiling point determined by?
Increases with size
32
How many kJ are in a kcal?
0.239
33
What is an intermediate?
A species that can be detected that exist for a short period of time
(not a TS)
34
What is a Bronsted Lowry acid?
A proton donator
35
What is a Lewis acid?
An electron pair acceptor
36
Are all Bronsted Lowry acids/bases Lewis acid/bases?
Yes --> but it is not reversible
37
What is the pKa of ammonia (NH3)?
36
38
What is the pKa of ammonium (NH4)?
9.3
39
What is the pKa of water?
15.7
40
If an acid has a higher pKa is is more/less acidic?
Less acidic
41
What is the pKa of alkanes?
45/46
42
What makes a compound visible under UV light?
Conjugated bonds
43
Compounds that contain only C and H are _____.
Hydrocarbons
44
What forces hold alkanes together?
Dispersion forces
45
What does an n in front of a compound mean?
Normal [unbranched (straight) chain with functional group in 1 position]
46
What is an iso group?
C with two methyl groups attached
47
Do constitutional isomers have the same name?
No, then they would be steroisomers
48
Steps for naming alkanes
a) Find longest chain of carbons
b) Number from end (lowest number to side with first branch)
c) Name groups (drop -ane and add -yl)
d) Prefix with number ex. di (separate with hyphens)
e) Alphabetical order
49
One rule for naming cycloalkanes
Start of point of maximum branching and number in direction of next branch
50
Degrees of unsaturation can be found by number of _____ and _____.
a) Rings and double bonds
b) Formula:
[(2 x C + 2) - H + N - X] / 2
51
What are enantiomers?
Non-superimposable mirror images
52
As chain length / surface area increases, bp ______.
Increases
53
Do even or odd numbered carbons pack better?
Even
54
Names of the alkanes 11-20
undecane
dodecane
tridecane
tetradecane
pentadecane
hexadecane
heptadecane
octadecane
nonadecane
eicosane
55
Suffix for alkanes with 20 carbons
Cosanes
56
Suffix for alkanes with 30+ carbons
Contanes
57
Atomic mass of Helium
4.00
58
Atomic mass of Lithium
6.94
59
Atomic mass of Beryllium
9.01
60
Atomic mass of Boron
10.81
61
Atomic mass of Fluorine
19.00
62
Atomic mass of Neon
20.18
63
What is a primary carbon?
A carbon with only one substituent (not hydrogen)
64
C-O-C group is called?
Ether
65
C - C - H
=O group is called?
Aldehyde
66
C = O
O group is called?
Ester
67
Does an amide or an amine group contain a double bond?
Amide
68
Is an eclipsed Newman Projection ever the most stable?
No - there is too much steric repulsion
69
What is an anti conformation?
The most stable (staggered and largest groups are furthest apart)
70
What is a gauche conformation?
Largest groups are close together but they are staggered.
71
Are axial or equatorial groups the most stable?
Equatorial
72
Why should the largest groups be equatorial?
To avoid 1-3 diaxial repulsions
73
Diastereomers have (the) same/different physical properties?
Different
74
What compound connects to form diamond?
Adamantanes
75
What is a bridgehead?
An atom where rings fuse
76
What must be added for halogenation reactions of alkanes?
Light
77
What are the two types of alkane reactions, and furthermore the subtypes of one?
a) Combustion
b) Halogenation
i) radical (two radicals formed)
ii) ionic (one ion formed and one electrophile)
78
What are the three steps of alkane halogenation?
Initiation
Propagation (2 steps)
Termination (3 steps)
79
In alkane halogenation, what position does the halogen attach to?
The least substituted carbon
80
Order radicals in order of stability
Most
Tertiary
Secondary
Primary
Methyl
Least
81
What is the Hammond Postulate?
When something is more reactive, it is less selective.
OR
When something is less reactive, it is more selective.
82
In an exothermic reaction, does the TS resemble the SM or the products more?
Starting materials
83
Rules for naming alkyl halides
a) Start at longest chain with max number of halogens/branches
b) Number from the end to give halide the lowest number
84
5 Physical Properties of Haloalkanes
1. Dipole-dipole interactions
2. Higher bp than alkanes
3. Good solvents for organic compounds
4. if % composition > 65% halogen; density 1.0g/mL
5. Immiscible in water
85
What is a stereogenic center?
Carbon with four different groups attached
86
What is a meso compound?
An achiral compound that has stereogenic centers
87
A clockwise center is _____ and a counterclockwise center is _____.
R, S
88
The priority 4 group must be to the ______ for a center to be opposite.
Front
89
When drawing an enantiomer, draw the same structure and _____ centers.
Invert/flip
90
Formula for determining stereoisomers
2 ^ n
91
What groups are towards you in a Fischer projection?
Horizontal
92
What stereoisomer rotates in a plane of polarized light?
Enantiomers
93
Dextrorotary means _______.
Levorotatory means _______.
Clockwise
Counter clockwise
94
Mixture of enantiomers is _____.
A racemic mixture/racemate
95
Two kinds of Substitution Reactions
a) Radical
b) Ionic
i) SN1
ii) SN2
96
What is a nucleophile?
A positive seeking species (negatively charged)
97
SN2 Mechanism
a) Bimolecular
b) Steric Bulk is the main barrier
c) Primary and Secondary are better
d) Charged or strong nucleophiles are better
e) Inverted Stereochemistry
f) Concerted
g) Rate is dependent on [Nu:] and [RX]
98
SN1 Mechanism
a) Unimolecular
b) Carbocation stability is the main barrier
c) Tertiary are better
d) Neutral or weak nucleophiles are better
e) Mixed stereochemistry
f) Stepwise
g) Rate is dependent on [RX]
99
Good Leaving groups
Sulfur thingy > I- > Br- > Cl->>> F-
100
Poor leaving groups
F-
OH-
OR-
NR2 -
R: -
H: -
101
How can bad leaving groups be made better?
By adding an acid
102
What hybridization of carbon will not undergo substitution?
sp2
103
Does a leaving group on a double bond leave?
No
104
What is another name for an alkene?
Olefin
105
What si another name for an alkyne?
Acetylene
106
Rules for naming alkenes/alkynes
a) Find longest chain with max number of double or triple bonds
b) Number from end to give first multiple bond the lowest number
c) Drop -ane and add -ene/-yne
107
Are trans and cis compounds the same molecule?
No, they are diastereomers
108
Which takes priority, a double bond or a halogen?
Double bond
109
E means same/opposite and Z means same/opposite
E means opposite and Z means same
110
What is a C5 unit called?
Isoprene
111
What is the pKa of alkenes?
~36
112
What is the pKa of alkynes?
~26
113
What are the names of isoprene containing compounds? Name the first 6.
Terpenoids or Isoprenoids
1. Hemiterpene
2. Monoterpene
3. Sesquiterpene
4. Diterpene
5. Sesterterpene
6. Triterpene
114
A reaction takes an acid from pKa 26 to pKa 36, will this work?
Yes, because reactions always go from a stronger acid (lower pKa) to a weaker acid.
