Linear Combination of Atomic Orbitals Video Lecture - Class 11

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before watching the video please make
sure that you have watched part 1 2 5 7
7 let's understand the linear
combination of atomic on C as we know
that atomic orbital is nothing but a
wavefunction sigh right this is nothing
but a syringe a wave equation but this
cannot be solved for system more than
one electron it can be solved only for
systemic as one later on correct so the
molecule orbital cannot be solved rumps
or in the radiation way because it has
more than one electron so what should we
do to overcome this method this la Ola
is a combination of atomic orbital has
been adopted this is an approximation
relation is assumed as a hydrogen
molecule it has two atoms a and B and
each hydrogen atom in the ground state
has one electron in the 1s orbital so
the atomic orbital of these can be
chosen by science IP function so I am
two hydrogen atoms and the orbitals will
be 1 s 1 s 1 s 1 they gave me the MS in
bite-sized ie function because this can
sigh and say we want you y hydrogen
atoms now if I want write molecular
orbital is nothing but you either do a
plus or minus right it is a constructive
interference or destructive so they are
two possible option that is bonding with
the plus you add this two wave function
and antibonding that you subtract this
to you because it's a way anyway orbital
is nothing but a wave function right so
and you add up you have a way of example
in this case right you can either do a
constructive or do a destructive
interference correct see you see it
which is the maxima and the Langan it
reaches out to the flat thing again it
is the maximum black so as well because
it is a constructive and destructive
interference going on
does you see the molecule orbital for my
edition of atomic orbital the class one
is called morning molecular orbital and
the one formed by subtraction is gone
and D morning anti-bonding molecular
beam and this has a star mark here he is
not her star mark in Santa morning this
is morning molecule or me
so the electron density in the bonding
molecular orbital is in bonding they are
more in this is empty morning so the
electron density is a bonding molecule
orbital if you see is going to be the
nuclei so this is my two nucleus and the
electron is around us right so the
repulsion between nickel a is very less
and thus it is stable if you see 90
bonding molecular orbital there is a
node here actually there is known here
would remain most of the electron
densities away from the nucleus machines
nucleus for the electrons up away from
the nucleus and as there is a high V
position
high diversion between the decrease
right and you the reversibility is very
high and this is unstable this is
unstable this is stable correctness also
if you see the electron blaze in the
bonding orbitals tend to hold the
nucleus together and stabilize the
molecule then the bonding molecular
orbital this this one has a lower energy
then the ending bonding in fact this has
lower energy than these two example if
this guy's has energy for the first four
this may have to just the number so this
has even lower energy than the atomic
orbitals which they combine and this in
the at all the electrons in this
antibonding molecular orbital the
destabilized molecule
because we shall represent correct so
therefore the energy increase but the
net energy see for example in this case
here it was for for doing them sport
become six the net energy will remain
same because law conservation of energy
ie does fortune fortunate so assume in
that case this income is 6 this becomes
2 just a number to understand me the
number may not be correct okay so if you
see this I have my science ID 2 atomic
orbital this is my wave function when
they combine they either go for bonding
molecular orbital or the anti-bonding
molecular right the bonding has a lower
energy the antibonding has higher energy
good let us understand the condition for
the combination of atomic already so
atomic orbital this combination takes
place only Eve the first condition is
the atomic orbitals must have same or
the early safe if they don't have same
energy of example I told write s and s
newly combined upon Sigma s or Sigma
star s so the energy has to be
comparable generally the the the energy
of the atomic orbital has to be
comparable to form molecular already
right and always the atomic orbitals
which they are combining they should
have seen symmetry about the nuclear
axis but the molecular axis we should
have seen symmetry overlap should be
maximum at the motor overlap the bed
result
atomic example if you see in this case I
have 2 atoms now they come towards each
other
this is overlap here right so it can
form a molecular orbital these s and s
also can form a molecular
correct so this P this P can form a
molecule orbiting it will grow like this
this s in this SK power well a little I
like for dot this P and this P can form
a little orbital and this one I will put
the Cosmo this P and this P can also
power my load so these two will form
Sigma molecular orbital these two will
also form sigma molecular orbital
because head-on overlap these guy the
crosswalk and with the Sigma they'll
form five molecular orbital correct the
concept is almost similar to the size
Sigma and PI bond but here instead of
bonds it's called orbital this is God's
Sigma molecular orbital because it is
symmetrical across this molecular sorry
about molecular axis if you take this
bond this atomic orbital when they form
the molecular orbital that molecular
orbital is symmetrical about this axis
so they are called Sigma Sigma means
symmetrical about molecular axis and pi
they're not submitted about one for X so
in this case if you see we saw that it
can form a sigma and sigma star if i was
going to have Sigma and Sigma star this
can have PI n PI star and this can also
have high in price up mark thank you
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