Molecular orbital theory based of lecture recording

Created by

Isabelle

Cards (34)

what how to describe a bond?
type of bond, shape, number of bonds
what are the 3 types of hybridisation?
sp3, sp2, sp
how many valence electrons are there in carbon?
4
what is pauling theory?
hybridisation
right these in descending order of energy: p,s, sp2, sp3, sp 
P
sp3
sp2
sp
s
what is the character of sp3?
1/4 s and 3/4 p
which p orbital always forms a sp hybrid?
Px, always on the bonding axis
what is a node?
an area of no electron density
what occurs in an antibonding orbital?
two opposite phases overlap forming a node
which way are sigma bonds symeterical?
along the x axis
why is an px not used for pi orbital?
they are used for head on overlap in sigma bond
how does antibonding form?
destructive interference
describe the bonding pi orbitals:
two areas of electron density above and below the plane
what is an antibonding orbital?
combination of an orbital in phase and one out of phase leading to a node where destructive interference means there is no electron density
why does a pi orbital have more energy?
it's less stable, due to a smaller overlap which means less efficient overlap
Pi orbitals are not cylindrical symmetrical
if both atomic orbitals have the same energy form?
homonuclear diatomic,
Purely covalent,
AOs combine equally
e- shared equally
if there is mismatch in energy of bonding orbitals what forms?
heteronuclear diatomic
In heteronuclear diatomic molecules which contributes more electrons to the molecular orbital?
In bonding orbitals: more electronegative AOs
In antibonding: more electropositive AOs
what does homo stand for?
highest occupied molecular orbital
what does lumo stand for?
Lowest Unoccupied Molecular Orbital
where does the nucleophile place the electron?
in the lumo
where is the electrophilic part of carbonal?
homo
what do you look at in a frontier molecular diagram?
the functional group bond
in a frontier mo diagram is c-h frame work shown?
no
why are pz and py pi bonds the same energy?
same energy just rotated differently
what does valence number equal?
Number of electrons in the outer shell. (group number)
why is oxygen sp2 hybridised in a double bond?
two lone pairs line in the same plane as the C-H bond, so froms a trigonal planar
what does a closer distance between MO and AO mean?
more electron density between that AO
when does conjugation occur?
when two double bonds within a organic molecule are separated by just one single bond
how does conjugation occur?
pz interact
why is the single bond in the delocalised system shorter?
some double bond character
which pi bond produces the lowest energy?
all in phase
how to count bonding interactions?
pz orbitals in the same phase next to each over