3.1-Rotations around a single bond

Question 1

what is different rotational arrangements called

Answer 1

conformation

Question 2

how does conformation change energy

Answer 2

not all conformations are equal in energy. some have lower energy then others

Question 3

what are newman projections

Answer 3

they are a type pf drawing where er imagine looking down a sigma bond. making it easier ti see angle between groups on each side

Question 4

how do we draw newman projections

Answer 4

the c atom closest to is drawn as a point other bonds from that atom become lines radiating from there in the directions their respective bonds point to

Question 5

what do you do if the atoms perfectly line up with eachother (eclipse)

Answer 5

just slightly off set them. clockwise or counter clockwise

Question 6

when examining the conformations of molecules what do we call the angles between the front Hs and the back Hs

Answer 6

this is called dihedral angles (or, torsion angle)

Question 7

what is a strain

Answer 7

when molecules are forced to adopt a conformation that isnt ideal

Question 8

what if molecules have a strain on them

Answer 8

then it raises the amount of energy associated with the molecule

Question 9

what are they types of strains

Answer 9

angle strain
torsional strain
steric strain

Question 10

what does angle strain arise form

Answer 10

bond angles deviasting from there ideal value

Question 11

what is the most common reason for angle strain

Answer 11

angle strain results from unusual geometry: forces the bond angles away from the ideal

Question 12

what kind of bonds dont create angle strain and what kinds of bonds do

Answer 12

angle strain is minimal with tetrahedral

angle strain is under tremendous stress in 3 remembered rings (so very reactive)

Question 13

what does torsional strains arise from

Answer 13

the electron clouds from two atoms that are seperated by exactly three bonds coming together too close

Question 14

why does torsional strain cost energy

Answer 14

because negative charges repel each other

Question 15

/torsional strain is very ____ in most molecules but usually has a ____ energy cost associated with it

Answer 15

common, small

Question 16

how do molecule like to rest

Answer 16

in the lowest possible energy state

Question 17

how do steric strains often arise from

Answer 17

two non-bonded atoms being in close proximity

Question 18

when are molecules considered non-bonded

Answer 18

if they are separated by more then three bonds (or if they are on a different molecule)

Question 19

what is the name of the conformation when substituents are directly in front of each other

Answer 19

eclipsed

Question 20

how high of a energy is an eclipsed conformation

Answer 20

it is the highest energy conformation because every atom in the front is experiencing torsional strain with the corresponding group i the back

Question 21

what is staggered conformation

Answer 21

when the atoms are maximum distance form eachother

Question 22

what is staggered energy conformation like

Answer 22

it is the lowest energy conformation because electron clouds are as far apart as possible

Question 23

even though some energies are higher and some are lower then others can the go back and forth from eclipsed and staggered

Answer 23

yes at room temperature they easily go to different conformations

Question 24

how do we usually name the conformation based on

Answer 24

the DA of the highest priority groups relevant to each other

Question 25

what is antiplainer

Answer 25

the conformation when the two large/high priority substituents are the maximum distance from eachother (180)

Question 26

what is the dihedral angle between the two high priority groups of a antiperiplainer

Answer 26

180

Question 27

what is the energy conformation of a antiperiplanar

Answer 27

it is the lowest energy conformation because there is no torsional strain and steric strain

Question 28

what is gauche conformation

Answer 28

it is staggered but the large/high priority groups are close to eachother

Question 29

what is the energy of the gauche conformation

Answer 29

it is the second lowest enegry because there is no torsional strain and only a little steric strain

Question 30

what is partially eclipsed conformation

Answer 30

partial because the largest group (CI) is eclipsed but with a smaller atom

Question 31

what is the dihedral angle between the two groups in partly eclipsed

Answer 31

120

Question 32

what is the energy of a partially eclipsed conformation

Answer 32

it is the second highest energy conformation because there is torsional strain but no steric strain

Question 33

what is fully eclipsed conformation

Answer 33

andgle between diheadral groups is 0

Question 34

what is the fully eclipsed conformation energy

Answer 34

the higest energy conformation because there is torsional strain and steric strains

Question 35

what is the energy of conformations dependent on

Answer 35

they dihedral angle of the large groups