Part 1 Flashcards
Formal charge formula
FC = valence e- - bonding e-
Formal charge:
| 1. - C - | \+ 2. - C - |
0 and 1
Difference between isomers and resonance structure
Isomers - different arrangement of atoms and electrons
Resonance structure - differ in arrangement of electrons
The only accurate representation of resonance stabilized compounds, due to delocalized e- density
Resonance hybrid
Trend for bond length in periodic table
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Which is stronger?
Sigma bond or pi bond
Sigma
Label each as Ionic or covalent
A. NaI B. BrCl C. HCl D. CH3NH2 E. NaOCH3
A. Ionic B. Covalent C. Covalent D. Covalent E. Ionic
The ____ the pKa, the stronger the acid
Lower
Acidity in periodic table
—->
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Arrange in increasing bond length
C-H
O-H
N-H
BCA
Arrange in decreasing bond length
HF
HCL
HBR
HBR>HCL>HF
Steps in drawing Lewis structure
- Count valence e-
- Count e- if there are no bonds (octet)
- Count bonded e- (bond e- = 1/2(step 2 - step 1)
Lewis acid
e- pair acceptor
Lewis base
e- pair donor
Bronsted-Lowry base
Proton acceptor
The stronger the acid, the _____ the conjugate base
Weaker
In proton transfer reactions, equilibrium favors the _____ acid and _____ base
Weaker, weaker
Factors that determine acidity (4)
- Element effects
- Inductive effects
- Resonance effect
- Hybridization effects
In hybridization effect in acidy, the acidity of HA increases as the percent s character of A _____.
Increases
Arrange in increasing acidity
sp
sp2
sp3
sp3 sp2 sp
What is the conjugate acid of each base
- H20
- NH2
- HCO3
- H20 - H30
- NH2 - NH3
- HCO3 - H2CO3
Rank in order of increasing acidity
NH3, H2O, HF
NH3 H2O HF
Rank the ff in order of increasing acidity
HBr, HCl, HF
HF < HCl < HBr
Acidity increases down a column
Difference between lewis acid and bronsted-lowry acid
A lewis acid is an electron pair acceptor and usually contains a proton of an unfilled valence shell of electrons. A bronsted lowry acid is a proton donor and must contain a hydrogen atom.
(All BL acids are lewis acids, though the reverse may not be true)
Classify each species as a lewis acid, bronsted-lowry or neither
H3O+
Cl3C+
BCl3
BF4-
H3O+ both
Cl3C+ lewis acid
BCl3 lewis acid
BF4- neither
Types of intermolecular forces of attraction (4)
- Van der Waals (LDF)
- Dipole-dipole
- Hydrogen bonding
- Ion-ion
Cause of dipole-dipole and give examples
It is due to the interaction of permanent dipoles
Ex. (CH3)2C=O, H2O
This is due to the electrostatic interaction if an H atom in an OH, NH, HF bond with another N, O or F atoms
H-bonding
Give example of ion-ion IMFA
NaCl, LiF
Van der waals or LDF is due to
Due to the interaction of temporary dipoles
Ex. All inorganic compounds
Arrange IMFA in increasingr strength
VDW-Dipole dipole-Hydrogen bonding-Ion Ion
Relation: Boiling Point and IMFA
3
- Stronger the forces the higher the BP
- for similar functional groups, the larger the area, higher BP
- more polarizable atoms, the higher the BP
Relation: Melting point and IMFA
- for compounds comaparable in MW, the stronger the forces the higher the MP (same as BP)
- with compounds with similar functional group, the more SYMMETRIC, the higher MP
Rank in increasing strength of IMFA
A. CH3NH2
B. CH3CH3
C. CH3Cl
BCA
Rank the compounds in order of increasing strength of IMFA
A. CH3Br
B. CH3I
C. CH3Cl
CAB
Rank the compounds in order of increasing strength of IMFA
A. NaCl
B. CH3OH
C. CH3Cl
CBA
Rank in increasing boiling point
A. CH3(CH2)4I
B. CH3(CH2)5I
C. CH3(CH2)6I
As is (high SA,high BP)
Rank the compounds in order of increasing melting point
A. (CH3)2CHOH
B. (CH3)3CH
C. (CH3)2C=O
BCA
Rank the compounds in order of increasing melting point
A. CH3F
B. CH3Cl
C. CH3I
ABC
Explain why benzene has a lower boiling point but much higher melting point than toluene
BP is solely determined by the strength of IMFA. Since bezene has a smaller size, it has less SA and weaker VDW interactions and therefore a lower boiling point than toluene. The increased MP for benzene can be explained by symmetry
Rank the compounds in order of increasing water solubility
A. (CH3)3CH
B. CH3OCH2CH3
C. CH3CH2CH2CH3
D. CH3CH2CH2OH
CABD
(For A: this nonpolar, hydrophobic molecule is mole compact making it more H20 soluble than its straight chain isomer
Molecular formula for alkanes
CnH2n+2
*cycloalkanes CnH2n
Alkane conformations can be classified as ____, ____, ____ or ____ depending on the relative orientation of the groups on adjacent carbons
staggered, eclipsed, anti or gauche
Staggered dihedral angle
60 degrees
Two reperesentation of conformers
Sawhorse and newman
Two types of isomers and its definitions
Constitutional isomer - isomers that differ in the way the atoms are connected to each other
Stereoisomer - isomers that differ only in the way atoms are oriented in space
of carbons gas, liquid, solid phase
Gas C1-C4
Liquids C5-C17
Solids >C18
Fuel for get engine
Kerosene (C9-C16)
Aka asphalt
Bitumen
Bromination - alkane
3* most stable
Two types of stereoisomers and its definition
Enantiomer - stereoisomer that are nonsuperimposable mirror images of each other
Diastereoisomers - stereoisomer that are not mirror images of each other
Difference of chiral and achiral
Chiral- must have 4 different groups attached
*chirality - with no plane of symmetry
Achiral - plane of symmetry
Ability of a compound to rotate plane-polarized light
Optical activity
A mixture having equal mixture of two enantiomers
Racemic mixture
Meso compunds are
Achiral with plane of symmetry
Diastereoisomers are
not mirror images, chiral
Number of stereoisomer (formula)
2^(n)
Arrange from highest to least priority
A. -F
B. -OH
C. NH2
D. CH3
ABCD
Arrange from highest to least priority
A. -Cl
B. -SH
C. -OH
D. -CH3
ABCD
State at room temp of covalent bond and ionic bond
Covalent bond - gaseous or liquid
Ionic bond - solid