WWU Chem 351 Chpt 1-2

Carbon typically makes how many bonds?  In regards to electrons, what else can we call Carbon?

4 bonds

 

Tetravalent

Nitrogen typically makes how many bonds?  In regards to electrons, what else can we call nitrogen?

3 bonds

 

“Trivalent”

Dipole Moment

Charge separation x bond length
Formal Charge
group # – # nonbonding electrons -1/2 shared electrons
What are the rules for resonance hybrids?

1. Valid Lewis structures

2 Only placement of electrons can shift, bond angles remain the same.

3. Number unpaired electrons remain the same.

4. Major contributor is lower energy.

5. Resonance stabilization is important when delocalizing charges over 2 atoms

Structural effects on acidity: electronegativity, size, resonance stabilization

 

EN= directly related to acid strength

Size= directly related to acid strength

Resonance Stabilization= More basic of ion has negative charge spread over less atoms.

Nucleophile

 

 

 

 

Electrophile

Electron donor

 

 

 

 

Electron Acceptor

sigma bonds
more elecron density along line connecting nuclei, more common
pi bonds
2 p-orbitals oriented perpendicular to the line connecting the nuclei, electron density above/below this line
sp hybrid

results in linear (180 deg) bond angle,

2 things attached to central atom

sp2 hybrid orbital
results in 120 deg bond angle, trigonal geometry w/ sometimes one unybridized pz perpendicular to the 3 sp2’s.
sp3 hybrid orbital
results in tetrahedral geometry, 109.5 deg bond angle, 4 bonding atoms
Rules of hybridization and geometry

1. sigma-bonding electrons and lone pairs CAN occupy hybrid

2. Use widest separatio, lone pairs want more space

3. In multiple bonding, 1st is a sigma, 2nd and 3rd are pi

Conformation
different in rotation about a single bond

Constitutional isomer

;

(structural isomer)

different in bonding sequence, increase as number of carbson increase due to carbon branching
Stereoisomers
different with how atoms are oriented in space

“cis–“

;

;

;

“trans–“

similar group on same side

;

;

;

similar group on opposite sides

Alkanes
Single bond, “–ane” suffix, undergo few rxns because have no fxnl groups.
alykyl group

alkane PORTION of a molecule with 1 hydrogen gone to allow functional group

;

“R”

Alkene

have a c-c double bond, “–ene” suffix, cis-trans isomerism common

;

if double bond switches, position denoted as a number (i.e. 1 versus 3-butanol)

Alkynes
c-c triple bond, “–yne” suffix, linear molecules

aromatic hydrocarbons

;

(arenes)

may be derivatives of benzene (“Ph”)

;

“Ar”

Alcohol

hydroxyl functional group, most polar

;

“R-OH”

Ether

2 alkyls with oxygen, polar but no H-bonding

;

R-O-R

Aldehydes and Ketones

Both have carbonyl (c=o) fxnal group, semi-sol in H2O

;

Ketone= Rc=OR’, “–one” suffix

Aldehyde= RHC=O “–al” or “–aldehyde” suffix

Carboxylic Acid
Carboxyl (–COOH) fxnal group, “—oic” suffix, polar, mostly sol in H2O
Carboxylic acid derivatives: acid chloride, ester, amide

all c=o with some other electron-hungry atom

 

acid chloride= R-COCl

Ester= R-COOR’

Amide= R-CONH2

Amine

Alkylated derivatives of NH3, basic

R-NH2

R-NH-R’

 

R-N-R

   |

   R

Amide
acid with NH3 or amine, most stable derivatives, weak bases with strong H-bonds
Nitriles
Cyano (–c3xN) fxnal group, strongly polar, semi-sol in H2O
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