Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OChem > Chapter 1: Bonding And Stereochemistry > Flashcards

Chapter 1: Bonding And Stereochemistry Flashcards

1
Q

Nucleophile vs electrophile

A
  1. Nucleophile: atom or functional group that forms a bond by donating a pair of electrons from a lone pair or pi bond (Lewis base)
    1a. Means nucleus loving…therefore any negative charge (electrons)
    1b. Attack Electrophiles (arrow is from nucleophile to electrophile)
  2. Electrophile: the atom or functional group with the concentration of positive charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Index of hydrogen deficiency (IHD) / degree of unsaturation (DoU)

A
  1. IHD=((2n+2)-H-X+N) /2
    1a. N=number of carbons
    1b. H=number of hydrogens
    1c. X=halogens (only if heteroatoms)
    1d. N=nitrogen (only if heteroatoms)
  2. Oxygens don’t change the IHD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Nomenclature functional groups

A
  1. Carboxylic acid: RCOOH: -oic acid
  2. Anhydride:
  3. Ester: RCOOR’ : -oate
  4. Amide: H2NCOR
  5. Aldehyde: RCOH
  6. Ketones: RCOR’
  7. Alcohols: ROH
  8. Thiol: R-SH
  9. Amines : R-NH2
  10. Alkene, alkyne, alkane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Carbon numbers

A
  1. Meth
  2. Eth
  3. Prop
  4. But
  5. Pent
  6. Hex
  7. Hept
  8. Oct
  9. Non
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Max number of Stereoisomers on a molecule

A

=2^n where n=number of chiral centres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Types of bonds

A
  1. Types:
    1a. Sigma: formed by head on overlap of orbitals along the axis between atoms
    1b. Pi: formed by side on overlap of parallel p orbitals
  2. Every bond has 1 sigma bond, the higher the bond order=more pi bonds
    2a. High bond order=high bond strength=high energy required to break bond=high stable=low potential energy=smaller bond length
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Lewis structure

A
  1. Carbon atoms are usually central
  2. Central is usually least EN
  3. Halogens (F, CL, Br, I) are usually terminal
  4. Hydrogen is always terminal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Exceptions to the octet rule

A
  1. Incomplete valence (ex: boron and its group)
  2. Expanded valence (ex: S, P, Cl-)
  3. Odd electron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Formal charge

A
  1. FC=VE-Dots-sticks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Lewis structure of oxyacids (hydrogen-nonmetal-lots of oxygens)

A

1, hydrogen is bonded to the oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Major resonance structures have:

A
  1. Full octet
  2. Minimum number of formal charges
  3. Negative formal charge on electronegative atoms
  4. Minimum separation between opposite formal charges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the notations of molecular structures that appear on the MCAT

A
  1. Line diagram: just draw line to represent carbons
  2. Wedge dash diagram: wedge is coming to you, dash is going away from you
  3. Fisher projection: horizontal/wedge to you, vertical/dash away from you
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

VSEPR Theory: basic geometry

A
  1. Hybridization: basic geometry : angles
    1a. Sp: linear: 180
    1b. Sp2: trigonal planar : 120
    1c. Sp3: tetrahedral: 109.5
    1d. Sp3d: trigonal bypyramidal: 90, 120
    1e. Sp3d2: octahedral: 90
  2. When doing this: lone pair is one group, double bond is one group (sp2), triple bond is one group (sp) etc.
  3. When an atom has resonance: it will choose the planar configuration (ex: sp2 vs sp3…will choose sp2)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

VESPR Theory: molecular geometry

A
  1. Types
    1a. Bent: AX2E
    1b. Trigonal bypyramidal: AX3E
    1c. Bent: AX2E2
  2. The more electrons, the smaller the angles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Delocalized electrons

A
  1. Electrons that extend over multiple bonds or atoms: movement of electrons from responance structures
  2. Increases stability of aromatic compounds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is a structure aromatic?

A
  1. Planar/fully conjugated: sp2
  2. Cyclical
  3. Obeys huckels rule: 4n+2=pi electrons (n=0, 1, 2, 3)
    3a. 1 double bond=2 electrons
    3b. Only count lone pairs of electrons when an atom is not attached to a double bond!
17
Q

Chirality

A
  1. Chiral molecules don’t have a plane of symmetry: so they rotate plane polarized light
  2. Chiral/sterogenic carbons: attached to 4 different groups
18
Q

Isomers

A
  1. Conformational (Conformers) isomers: same molecular formula and connectivity but structure differs by rotation around carbon-carbon single bonds (shown in Newman projections)
    1a. Eclipsed: high energy=least stable=big groups overlap=steric hinderance
    1b. Staggered: low energy=more stable=big groups opposites (anti staggered; most stable) or big groups far apart (gauche staggered)
  2. Constitutional (structural) isomers: different atom connectivity (move around skeleton)
  3. Stereoisomers: same atomic connectivity but different arrangement in space
    2a. Enantiomers: opposite stereochem at all stereo centres, identical physical properties (only difference is they react different in chiral environment & rotate plane polarized light in opposite directions)
    2b. Diastereomers: must have at least 1 diff and 1 same stereocentre (ex: cis/trans or E/Z alkanes)
    2bi. Epimers: differ at only one chiral carbon
    2bi1. Anomers: type of epimer that is a cyclic carb that differs at only one chiral carbon (Alpha: when C1 and C6=opposites (alpha=down), Beta: when C1 and C6=same (alpha is up))
19
Q

Geometric isomers: (cis/trans , E/Z)

A
  1. Cis/trans
    1a. Cis: 2 long carbon chains on same side
    1b. Trans: 2 long carbon sides are on opposite sides (more stable)
  2. Cahn ingold prelog state
    2a. Z: 2 high priority on “zee” same side
    2b. E: enemies: on opposite sides
20
Q

Absolute configuration: R (right) vs S (left)

A
  1. Rule 1: if lowest priority is at back… number others in order of priority and count
  2. Rule 2: if lowest priority is at front… number others in order of priority, count, and switch to opposite sign
  3. Rule 3: if lowest priority is not at front or back…
    3a. Switch group to get it in back, and switch other two groups…count as rule 1
21
Q

Racemic mixture

A
  1. A mixture that is 50:50 of 2 enantiomers so there is no net rotation of plane polarized light
    1a. Can be separated if enantiomers react with another chiral molecule to produce Diastereomers salts
22
Q

Meso compounds

A
  1. Compounds that have a chiral carbon, but are not chiral (they don’t have symmetry)
    1a. Need a min of 2 stereocenters,
23
Q

Types of chromatography

A
  1. Thin layer: separate based on polarity
  2. Gas: separate based on boiling points
  3. Size exclusion: separates based on size
  4. Ion affinity: separates based on charge
  5. Affinity: separates based on affinity
24
Q

Resolution: Separation of enantiomers

A
  1. Add enantiometrically pure reagent that forms salt w mixture
  2. Reaction yields Diastereometric salts (non identical physical properties)
  3. Now can physically separate the salts
25
Q

Liquid-liquid Extraction:

A
  1. Organic solvent (non polar) has an aqueous solvent added (acidic, basic or neutral) and the phases separate …aqueous phase links bc denser
26
Q

Thin layer chromatography

A
  1. Stationary phase: species stuck to plate ….Mobile phase: solvent that travels up plate
  2. More polar compound is lower /stops earlier
  3. Retention factors: distance compound travelled/distance solvent travelled

OChem (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions