CHEM 261 Exam 1

ionic bond

the bond that forms when an electron is transferred between a cation and an anion

covalent bond

the bond that forms when an electron is shared between 2 anions

polar covalent bond

a covalent bond that forms when an electron is unequally shared between two anions

nonpolar covalent bond

a covalent bond that forms when an electron is equally shared between two anions

3 types of molecular geometries used in orgo

1. linear

2. trig planar

3. tetrahedral

linear HO and angles

sp orbital

180° angles

trig planar HO and angles

sp² orbital

120° angles

tetrahedral HO and angles

sp³ orbital

109.5° angles

3 types of HO used in orgo

1. sp

2. sp²

3. sp³

formula for the # of hybrid orbitals

# of sigma bonds + # of lone pairs

formal charge formula

the # of valence electrons = [ # of non-bonding electrons - ½ (# of bonding electrons) ]

3 formal charge rules

1. the sum of all formal charges in a neutral molecule must be 0

2. the sum of all formal charges in an ion must equal the charge of the ion

3. a negative formal charge will reside on the most electronegative atom

sigma bonds

bonds that form when hybrid (s&p) or unhybridized (p&d) orbitals overlap

pi bonds

bonds that form only when unhybridized p orbitals overlap side to side

electronegativity

an atoms ability to attract electrons towards itself

electronegativity trends

increases from bottom to top

increases left to right

non-polar covalent bond electronegativity range

0 - 0.4 ΔEN

polar covalent bond electronegativity range

0.5 - 1.7 ΔEN

ionic bond electronegativity range

> 1.8ΔEN

3 rules of drawing chemical structures

1. carbon atoms arent shown

2. hydrogen atoms bonded to carbon arent shown

3. only atoms other than carbon & hydrogen are shown

acid

a substance that can donate a proton (H+) and accept an electron pair

base

a substance that can accept a proton (H+) or donate an electron pair

conjugate base (CB)

the product that forms when an acid looses a proton (H+)

conjugate acid (CA)

the product that forms when a base gains a proton (H+)

pKa acid strength trend

the stronger the acid, the smaller the pKa value

prefix for 1

meth

prefixes for 2

eth

di

prefixes for 3

prop

tri

prefixes for 4

but

tetra

prefix for 5

penta

prefix for 6

hexa

prefix for 7

hepta

prefix for 8

octa

prefix for 9

nona

prefix for 10

deca

alkane

a hydrocarbon that is composed of carbon-hydrogen single bonds

alkyl

a partial structure that forms when a H is removed from an alkane

branched alkyl

a partical branched structure that forms when a H is removed from an internal C

4 common branched alkyl groups

1. isopropyl

2. isobutyl

3. sec-butyl

4. tert-butyl

formula for naming an alkane with 1 substituent

sub location - sub name - longest chain

formula for naming an alkane with 2 of the same substituents

sub 1 location, sub 2 location - prefix - sub name - longest chain

formula for naming an alkane with 2 different substituents

sub 1 location - sub name - sub 2 location - sub name - longest chain

alkane carbon chain rule

if there are multiple long carbon chains, number the chain so that the substituents are on the lowest carbon chain number

4 types of alkyl groups

1. primary C

2. secondary C

3. tertiary C

4. quaternary C

primary carbon

a carbon atom that is bonded to one carbon and 3 hydrogens

secondary carbon

a carbon atom that is bonded to two carbons and two hydrogens

tertiary carbon (3C + H)

a carbon atom that is bonded to three other carbons and one hydrogen

quaternary carbon

a carbon atom that is bonded to four carbons and 0 hydrogens

14 orgo 1 functional groups

1. alkene

2. alkyne

3. arene

4. halide

5. alcohol

6. ether

7. amine

8. imine

9. nitrile

10. aldehyde

11. ketone

12. carboxylic acid

13. ester

14. amide

3 functional groups with carbon carbon multiple bonds

1. alkene

2. alkyne

3. arene

alkene functional group

a hydrocarbon that contains at least one carbon - carbon double bond

alkyne functional group

a hydrocarbon that contains at least one carbon - carbon triple bond

arene functional group

a hydrocarbon that is composed of 6 carbons that have alternating double and single bonds (aromatic ring)

benzene ring

a structure that is composed of 6 carbons and 6 hydrogens (3 double bonds & 3 single bonds)

4 functional groups with carbon bonded to an electronegative atom

1. halide

2. alcohol

3. ether

4. amine

halide functional group

composed of a carbon single bonded to (F, Cl, Br, or I) and single bonded to 3 R groups

alcohol functional group

composed of a carbon single bonded to OH (hydroxyl group) and 3 R groups

ether functional group

composed of an oxygen that is single bonded to two carbon groups

amine functional group

composed of a lone pair nitrogen that is single bonded to a carbon group and two R groups

imine functional group

composed of a lone pair nitrogen that is double-bonded to a carbon and single bonded one R group

nitrile

composed of a carbon that is triple-bonded to nitrogen and single-bonded to one R group

carbonyl group

a functional group that contains a carbon double bonded to an oxygen

5 functional groups that contain a carbon-oxygen double bond (carbonyl group)

1. aldehyde

2. ketone

3. carboxylic acid

4. ester

5. amide

aldehyde functional group

composed of a carbonyl group that is single-bonded to a hydrogen and an R group

ketone functional group

composed of a carbonyl group that is single-bonded to two carbon groups

carboxylic acid functional group

composed of a carbonyl group that is single bonded to an OH and one R group

ester functional group

composed of a carbonyl group that is single-bonded to an R group and single-bonded to a different oxygen

amide functional group

composed of a carbonyl group that is single bonded to an R group and single bonded to a lone pair nitrogen

conformation

an arrangement of atoms that results from bond rotation

eclipsed conformation

the unstable arrangement of atoms around a carbon-carbon single bond in which the bonds in the front line up with the bonds in the back and create torsional strain

staggered conformation

the stable arrangement of atoms around a carbon-carbon single bond in which the bonds in the front dont line up with the bonds in the back

anti-confirmation

a type staggered confirmation in which the two largest substituent groups are 180° apart

gauche confirmation

a type of staggered conformation in which the two largest substituent groups are 60° apart with steric strain

cycloalkanes

an alkane that contains a ring of carbon

3 carbon cyclohexane name

cyclopropane

4 carbon cyclohexane name

cyclobutane

5 carbon cyclohexane name

cyclopentane

6 carbon cyclohexane name

cyclohexane

7 carbon cyclohexane name

cycloheptane

8 carbon cyclohexane name

cyclooctane

stereoisomers

compounds that have the same amount of carbon and hydrogen and the same connectivity but different 3D arrangements

2 types of stereoisomer

1. cis isomers

2. trans isomers

cis isomer

a generally unstable stereoisomer that has two substituent groups on the same side

trans isomer

a generally stable stereoisomer that has two substituent groups on different sides

3 components of cyclohexane strain E

1. angle strain

2. torsional strain

3. steric strain

angle strain

a type of ring strain that occurs when the bond angles in a molecule are are forced to deviate from the ideal 109.5°

torsional strain

a type of conformational strain that occurs during eclipsing conformation when the bonds between neighboring atoms eclipse

steric strain

a type of conformational strain that occurs when two substituents groups are 60° apart

what is the most strained cycloalkane and why?

cyclopropane is the most strained because of its 60° bonds and its eclipsing C-H bonds

what is the most stable cycloalkane and why?

cyclohexane is the most stable because it adopts chair confirmation

chair confirmation

a 3D confirmation of cyclohexane that resembles the shape of a chair and has the lowest energy confirmation (staggered C-H bonds & bonds near 109.5°)

boat confirmation

a 3D confirmation of cyclohexane that resembles the shape of a boat and has steric & torsional strain but no angle strain (bonds near 109.5°)

2 substituent group positions on a cyclohexane

1. axial position

2. equatorial position

axial groups

substituents or functional groups that point straight up or down and lie parallel to the vertical ring axis

equatorial groups

substituents or functional groups that point slanted up or down and lie parallel to the horizontal ring equator

axial & equatorial positions rule

on a cyclohexane axial positions alternate up and down and equatorial positions alternate slightly up and slightly down

ring flip

a motion that converts axial up substituents into equatorial up substituents and axial down substituents into equatorial down

4 ring flip rules

1. cis isomers remain cis isomers

2. trans isomers remain trans isomers

3. axial up converts into equatorial up

4. axial down convert into equatorial down

monosubstituted cyclohexane rule

if there is only one substituent group on a cyclohexane it will be most stable in the equatorial position

1, 3 di axial interaction

the strain energy that is caused by a steric interaction between three axial groups located on carbons 1, 2,&3