Organic Chem 1 Exam

3 Rules Used to Determine Ground State Electron Configuration

1. Aufbau procedure
2. Ponli Exclusion Principle
3. Hund’s Rule

Aufbau Procedure

building up

Ponli Exclusion principle

a max of 2 e- per orbital, but they must have opposite spin

Hund’s Rule

parallel before pairing up

Bonding Model 1: Lewis Structure and Octet Rule

atoms lose/gain/share electrons to get a noble gas configuration

lewis structure is also called

line-bond structure

Constitutional Isomers

isomers in which atoms are attached in a diff order

ex: CH3OCH3 & CH3CH2OH (BOTH C2H6O)

sigma bond

electron density concentrated along internuclear axis

\-----o------o-----

pi bond

electron density concentrated above and below internuclear axis

1 single bond =

1 sigma bond

1 double bond =

1 sigma and 1 pi bond

1 triple bond =

1 sigma and 2 pi bonds

sp3 hybridization characteristics

1. 4 equivalent sp3 hybrid orbitals available for sigma bond
2. same characteristic of C w 4 single bonds
3. tetrahedral
4. 109.5 bond angles
5. 25% s character and 75% p character

sp2 hybridization characteristics

1. 3 equal lower energy sp2 orbitals
2. trigonal planar
3. 120 bond angle
4. 1 higher energy orbital available for pi bond
5. sam characteristic of c w 3 sigma and 1 pi bond (2 single and 1 double bonds)
6. 33% s character 66% p character

sp hybridization characteristics

1. 2 equal lower energy sp orbitals
2. linear
3. 180 bond angle
4. 2 higher energy available for pi bonds
5. same characteristic of c w 2 sigma bonds and 2 pi bonds (triple bond w single bond)
6. 50% s character and 50% p character

how to determine hybridization

\#of sigma bonds + #of lone pairs

the better the overlap of orbitals,

the stronger the bond

how to tell strongest c-h bond

sp>sp2>sp3

2 types of molecular orbitals i need to know

bonding and antibonding

2 equal AOs interact to form 2 MOs:

bonding and antibonding

bonding MO is _______ in energy than AOs

lower

antibonding MO is _____ higher in energy than AOs

higher

bonding MOs designated by sigma and pi while antibonding MOs have

sigma star\* and pi star

2 equal s orbitals form

lower energy sigma bonding MO or higher energy sigma star antibonding MO

2 parallel p orbitals result in

lower energy pi bonding MO and higher energy pi star antibonding MO

order of atoms electronegativity trend

F>O>N, Cl>Br>C>H>Mg, Cu, Li, Na

inductive effect

shifting of electrons in a sigma bond in response to the electronegativity of nearby atoms

inductive effect occurs through

sigma bonds due to electronegativity

resonance effect occurs through

pi bonds and pi electrons

steric effects

occurs when atoms or groups of atoms approach each other too closely

polar molecules has unequal charge due to

bonds and shape

nonpolar if

bond dipoles are symmetrically oriental

molecule itself is nonpolar

shape is linear or tetrahedral

bond dipole refers to ___ while

dipole moment refers to

single bond

molecule as a whole

polarity of hydrocarbons

nonpolar

cis is __

while trans is __

polar

nonpolar (anticoplanar)

formal charge =

\#of valence electrons - (count every dot once and every line once)

carbon typically has ___ bonds

4

nitrogen typically has ___

3 bond and 1 lone pair

oxygen typically has ___

2 bonds and 2 lone pairs

when carbon has 3 bonds it has

a positive formal charge and is a carbocation

when nitrogen has a positive charge when

it has 4 bonds

oxygen has a positive charge when

it has 3 bonds and 1 lone pair

carbon has a negative charge when

it has 3 bonds and 1 lone pair

nitrogen has a negative charge when

it has 2 bonds and 2 lone pairs

oxygen has a negative charge when

it has 1 bon and 3 lone pairs

3 intermolecular attractive forces

1. dipole dipole
2. london dispersion
3. hydrogen bonding

characteristics of dipole dipole attractions

1. between polar molecules
2. molecules of equal size and mass, attraction increases w increasing polarity

characteristic of london dispersion forces

1. due to temporarily induced dipoles
2. in polar and nonpolar molecules

large molecules are more easily ____, so LDS _ with size

polarized, increase

substances w large atoms will have _ melting points and boiling points (if nothing else is present)

higher

branched hydrocarbons have less _ *than straight chain hydrocarbons, so they have* _ boiling points

surface area

lower

diatomic halogens in bp order

F2

hydrogen bond in an ATTRACTION between

very polarized hydrogen on 1 molecule and very electronegative atom on adjacent molecule

ex of polarized hydrogens:

H-O, H-F, H-N

ex of very e- atom

F, O, N

Characteristics of hydrogen bonding

1. higher mp and bp if comparable compounds are similar in size


1. higher solubility in substances they can bond to

if an chemical ends in -ol

alcohol with an OH

ends in -al

aldehyde with a carbon double bonded to an oxygen with a hydrogen H-C=O

…………………….|

\-one

ketone with carbon double bonded to oxygen C=O

\-ic acid

carboxylic acid; basically a carbon double bonded to an oxygen and bonded to an OH

HO-C=O

\-yl -oate

ester bond; C-CO-O-C

Carbon bonded to carbon thats doubly bonded to oxygen and that C is single bonded to another oxygen and another carbon

ether

C-O-C

\-ene

alkene

double bond with C

C=C

hybridization of carbocation

sp2 bc 3 bonds

resonance structure

any valid lewis structure for any molecule or ion; contribute to resonance hybrid

resonance hybrid

true molecule

steps to identifying resonance structures:

1. less formal charge, the better
2. better to have - charge on more e- atom
3. avoid like charges on adjacent atoms

more resonance structures, the more

stable a molecule

what moves when drawing resonance structures

only electrons

NOT ATOMS

resonance only goes through

sp2 hybridized atoms

NEVER SP3

for resonance structures, push electrons *from negative or*

away from negative or toward positive

hydrocarbon

only C and H

examples of hydrocarbons

alkanes, alkenes, alkynes, arenes

alkane

all C-C bonds are single bonds

alkene

C=C

alkyne

carbon triple bond

arenes

benzene rings

alkyl halides

C-X (X=halogen, Cl, Br, I)

Functional groups with C-O single bonds

alcohols, phenols, ethers

alcohols

R-OH

phenols

benzene ring with OH attached

ethers

C-O-C

Functional groups with C=O double bonds

aldehydes, ketones, carboxylic acids, carboxylic acid derivatives that replace OH

aldehydes

carbonyl group - H-C=O

carbon bonded to R and H and double bond to O

ketones

double bond to O and 2 other R --C=O

carboxylic acids

COOH

R-OH-C=O

ester

carboxylic acid derivative -OR

amide

carboxylic acid derivative -NR2

acid chloride

carboxylic acid derivative -Cl

acid anhydride

carboxylic acid derivative -OCOR

nitrogen containing compounds

amines, amides

amines

R-N-R-R

amide

RCO-NR2

sulfur containing compounds

thiols and sulfides

thiols

R-SH

sulfides

R-S-R

the larger the Ka, the _ *the pKa, the* _the acid

smaller, stronger

stronger an acid,

weaker its conjugate base

CH3COOH pka and C.B.

4\.75

CH3COO-

Phenol (benzene ring w OH) pka and C.B.

9\.9

Phenoxide (benzene ring w O and 3 lone pairs)