3.1-Rotations around a single bond Flashcards
(35 cards)
what is different rotational arrangements called
conformation
how does conformation change energy
not all conformations are equal in energy. some have lower energy then others
what are newman projections
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
how do we draw newman projections
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
what do you do if the atoms perfectly line up with eachother (eclipse)
just slightly off set them. clockwise or counter clockwise
when examining the conformations of molecules what do we call the angles between the front Hs and the back Hs
this is called dihedral angles (or, torsion angle)
what is a strain
when molecules are forced to adopt a conformation that isnt ideal
what if molecules have a strain on them
then it raises the amount of energy associated with the molecule
what are they types of strains
angle strain
torsional strain
steric strain
what does angle strain arise form
bond angles deviasting from there ideal value
what is the most common reason for angle strain
angle strain results from unusual geometry: forces the bond angles away from the ideal
what kind of bonds dont create angle strain and what kinds of bonds do
angle strain is minimal with tetrahedral
angle strain is under tremendous stress in 3 remembered rings (so very reactive)
what does torsional strains arise from
the electron clouds from two atoms that are seperated by exactly three bonds coming together too close
why does torsional strain cost energy
because negative charges repel each other
/torsional strain is very ____ in most molecules but usually has a ____ energy cost associated with it
common, small
how do molecule like to rest
in the lowest possible energy state
how do steric strains often arise from
two non-bonded atoms being in close proximity
when are molecules considered non-bonded
if they are separated by more then three bonds (or if they are on a different molecule)
what is the name of the conformation when substituents are directly in front of each other
eclipsed
how high of a energy is an eclipsed conformation
it is the highest energy conformation because every atom in the front is experiencing torsional strain with the corresponding group i the back
what is staggered conformation
when the atoms are maximum distance form eachother
what is staggered energy conformation like
it is the lowest energy conformation because electron clouds are as far apart as possible
even though some energies are higher and some are lower then others can the go back and forth from eclipsed and staggered
yes at room temperature they easily go to different conformations
how do we usually name the conformation based on
the DA of the highest priority groups relevant to each other
