GChemOChem

Question 1

Can sigma bonds rotate?

Answer 1

Yes, they are cylindrical single bonds that can rotate

Question 2

Can you rotate a pi bond?

Answer 2

No they cannot rotate. They are locked in

Question 3

Double bonds consist of …

Answer 3

one sigma and one pi

Question 4

Triple bonds consist of

Answer 4

one sigma and two pi bodns

Question 5

As you increase the bond order you are increasing the bond

Answer 5

bond strength

Question 6

As stability goes up, energy …

Answer 6

energy goes down

Question 7

As strength goes up the bond length goes

Answer 7

down (we are pulling the atoms closer together)

Question 8

Are pi bonds weaker than sigma bonds?

Answer 8

Yes they are. But because double bonds are pi and sigma they ar strong

Question 9

are cis or trans more stable

Answer 9

trans is usually more stable b/s molecules like to spread things out as much as possible (less steric hindrance)

Question 10

What is the hack for lewis structures. Aka what is the shorcut to knowing how many bonds the central atom wants?

Answer 10

F- 1 bond
O- 2
N- 3
C- 4
B- 3
Be- 2
H- 1

This refers to the column in the periodic table

Question 11

What are 3 elements that can have an expanded valence?

Answer 11

Phosphorous, sulfur, chlorine

Question 12

You can think of formal charge as

Answer 12

atomic suffering in absolute value

Question 13

Formal charge =

Answer 13

of valence electrons from the coloumn - # of electrons in lone pairs - # of bonds. You state the number of valence electrons in the central atom (N=5) and then count down from there. So NH3 has 5 a 0 because it has 3 bonds to hydrogen and then one lone pair (2 e-)

Question 14

Remeber this is a shortcut for Formal charge

Answer 14

just look at the coloumn number for central atom and minus

Question 15

Oxyacid

Answer 15

The acidic part - the proton that is going to leave - is not bonded to the central atom but to an oxygen ex H2SO4

Question 16

Examples of oxyacids

Answer 16

HNO3
H2CO3
H3PO4
Hydrogens are attached to the oxygen

Question 17

What bonds cannot be broken in resonance structures

Answer 17

sigma

Question 18

What are the 4 rules for determining the best response structure

Clarify the question

Answer 18

Full octet
Minimum number of Formal charges
Negative FC on electronegative atoms
Minimum separation between opposite Formal charges

Question 19

Dashed is ___

Answer 19

away (dashing away)

Question 20

Wedge is

Answer 20

toward

Question 21

Fischer projection

Answer 21

Horizional - hugs toward you

Question 22

Tetrahedral

Answer 22

109.5 degrees

Question 23

When you add the exponents you get the number of groups

Answer 23

i.e sp=2 exponents so 2 groups

Question 24

If the resonance structures have access to sp2…

Answer 24

it will be sp2 (it wants to be planar)

Question 25

If an atom has a choice between sp2 or sp3 it chooses..

Answer 25

sp2 (planar)

Question 26

molecular geometry does not consider ___

Answer 26

lone pairs. only bonds (bent)

Question 27

lone pairs take up more/less space than bonds

Answer 27

more

Question 28

arrange ammonia methane and water from largest to smallest bond angles

Answer 28

methane, ammonia, water

Question 29

Delocalized electrons

Answer 29

e- that can move

Question 30

To determine is a species is aromatic we apply ___ rule

Answer 30

Huckel's

Question 31

Huckel's rule (4)

Answer 31

1. planar 2. Cyclic 3. Fully conjugated alternating single and double bonds (all sp2) 4. Obeys Jucke's Rule (contains a total of 4n + 2pi electrons) answer needs to be a whole number

Question 32

pi electrons can be (2)

Answer 32

1. pi bonds 2. electrons that can become pi bonds

Question 33

Is pyrrole aromatic

Answer 33

yes

Question 34

Is imidazole aromatic

Answer 34

no

Question 35

a lone pair on a double bond does ___ contribute to aromaticity

Answer 35

not

Question 36

hucks rule formua

Answer 36

4n+2=6pi e-

Question 37

Chirality ____ be superimposed on its mirror image such as

Answer 37

cannot, hands

Question 38

a chiral carbon as 4 ___ groups

Answer 38

different

Question 39

an achiral carbon has two __ groups

Answer 39

identical

Question 40

when looking for chiral centres look for at least -- explicit bonds

Answer 40

3

Question 41

constitutional isomers

Answer 41

construction. structural

Question 42

conformational

Answer 42

rotation about their c-c single bonds

Question 43

is staggered or eclipsed more stable

Answer 43

staggered because the hydrogens are spaced out

Question 44

Cahn-Inglod-Prelog state rules (3)

Answer 44

The highest atomic number takes greatest priority When two atoms bound to the alkene carbon atom are the same, look to the adjacent atom until a diff is found Double bonds take a higher priority since they are theoretically bonded twise to the same atom

Question 45

E-isomer

Answer 45

opposite side (enemies)

Question 46

Z-isomer

Answer 46

same side (zame zide)

Question 47

do cis and trans always = E/Z

Answer 47

no

Question 48

enantiomers

Answer 48

mirror image that is not the same

Question 49

enantiomers (5)

Answer 49

1. opposite steroechemistry at all sterocenters 2. identical physical properties (bp.polarity) 3. React identically in most environments 4. react differently in chiral environ 5. rotate plane-polarized light oppositely

Question 50

absolute config

Answer 50

R/S

Question 51

R

Answer 51

right - clockwise

Question 52

S

Answer 52

left - counterclockwise

Question 53

Racemic

Answer 53

no net rotation of plane-polarized light - cancel out

Question 54

Diastereomers

Answer 54

some R/S flip but not all (could be RR and flip to RS)

Question 55

Meso

Answer 55

contain two chrial centres but themselves are achrial

Question 56

Do Meso compounds rotate plane polarized ligth

Answer 56

no

Question 57

Meso needs a ___ plaen

Answer 57

mirror

Question 58

To rotate plane polarized light you need to be ___ and not ___

Answer 58

chiral, meso

Question 59

Sterospecific

Answer 59

only create one kind of enantiomer

Question 60

Stereoselective

Answer 60

favor one enantiomer but makes others

Question 61

which compund travels further in TLC the polar or non-polar

Answer 61

the less polar travels further (higher)

Question 62

Retention factor

Answer 62

distance compound traveled/distance solvent traveled

Question 63

Fractional crystallization is seperated by

Answer 63

solubility

Question 64

What two things must we look for to resolve a racemic mixture of acidic enantiomers?

Answer 64

1) chiral - more than 3 unique bonds 2) basic

Question 65

Meso compunds are ____ and they contain a ___ carbon. They do not _________ light

Answer 65

achrial, chiral, rotate plae polarized lgiht

Question 66

Chiral molecules are never the same as their ____ image

Answer 66

mirror

Question 67

All chiral molecules have a mirror image which is their

Answer 67

enantiomer

Question 68

If a molecule is not the same as its mirror image, then it is ___

Answer 68

chiral

Question 69

A lewis base ___ electrsons and is ___philic

Answer 69

doantes e- and is nucelophilic

Question 70

The freezing point of fatty acids is greatest in...

Answer 70

saturated fatty acids

Question 71

are unsaturated or satured have lower melting points

Answer 71

unsaturated

Question 72

At low temp the anti conformattion is the most common (t/F)

Answer 72

T

Question 73

ic acid

Answer 73

carboxylic acid

Question 73

-oate

Answer 73

ester