Intro to ochem Flashcards
(170 cards)
sigma bonds
forms when the bonding pair of electrons are localized to the space directly between the two bonding atoms. it is the lowest energy strongest and most stable type of covalent bond
a pi orbital
is created by overlapping p orbitals
sigma bonds are formed
in the area where hybrid orbitals of two atoms overlap
pi bonds are formed
by the overlap of pure p orbitals
number of hybrid orbitals must equal the
number of sigma bonds plus the lone pairs
valence shell electron pair repulsion
states that electrons in an orbital seek to minimize their energy by moving as far away from other electron pairs as possible, minimizing the repulsive forces between them
sp angle
180
sp2 angle
120
sp3
109.5
sp3d
90,120
sp3d2
90,90
delocalized electrons
sometimes bonding electrons are spread out over three or more atoms
aromaticity
is the increased stability of a cyclic molecule due to electron delocalization. must follow huckel’s rule 4n+2 will be aromatic
nucleophiles are also called
lewis bases, with a partial negative charge seeking positively charged nuclei
electrophilic functional groups
have a partial positive charge and seek electrons
structural isomer
have the same molecular formula but different bond-to-bond connectivity
conformational isomers
are not true isomers. they are different spatial orientations of the same molecule
highest energy conformation and lowest
eclipsed and staggered
stereoisomers
two unique molecules with the same molecular formula and the same bond-to-bond connectivity
enantiomers
are non-superimposable mirror images of one another. they have the same molecular formula and connectivity but are not the same molecule because they differ in their configuration. they must have opposite absolute configuration at each and every chiral carbon. have the same chemical properties
chirality
a carbon is chiral when it is bonded to four different substituents
relative configuration
is not related to absolute configuration but two molecules have the same relative configuration about a chiral carbon if they differ by only one substituent and the other substituents are oriented identically about the carbon
to find how a configuration rotates light you have to find it
experimentally
if the compound rotates plane polarized light clockwise
it is designated with + for dextrorotary