hybridization of atomic orbitals and spsp2 sp3 hybridization of carbon firstly let me
teach you that what is hybridization well the word hybridization means mixture for example
when you mix salt plus water you get a mixture when you mix sugar plus water you get a mixture
similarly consider two atomic orbitals s orbital and p orbital when these two orbitals mix
are combined together they form hybrid orbitals this noted down that hybridization is the mixture
or combination of atomic orbitals just like the mixture of salt and water are mixture of sugar
and water in this lecture for simplicity i would often use mixture of atomic orbitals
which would mean hybridization of atomic orbitals i do so so that you could easily understand
it hence we define hybridization as when different atomic orbitals of same or nearly same energy
combined together to form new hybrid orbitals is called hybridization for example the energy of s
orbital is smaller than p orbital but nearly they have the same energy so they combine together to
form hybrid orbitals here you must learn that why we need to study hybridization of atomic orbitals
well hybridization of atomic orbitals teach us two important concepts it shows us molecular geometry
or shape of the molecules secondly it shows us the bonding of atomic orbitals you will learn more
about the molecular geometry and bonding of atomic orbitals in this lecture secondly why atomic
orbitals are hybridized or why hybridization take place well there are different theories which
explain this concept but i am going to explain it very easily consider two types of atoms a atom
and b atom that a atom has two orbitals s orbital and p orbital while b atom have only one orbital
like s orbital now let a atom react with two atoms of b to form a molecule we can see that there is
ss bond between a atom and b atom while here is sp bond between a atom and b atom we can see that
ss bond is totally different from sp bond it means that a atom form two types of bonds with the same
atom of b which is impossible not understandable and hundred percent wrong thus to solve this
issue we look at the hybridization of atomic orbitals or mixture of atomic orbitals now
s orbital and p orbital would combine together to form two hybrid orbitals known as sp orbitals here
this is sp orbital and this is also sp orbital hence this sp orbital of air atom will form
covalent bond with s orbital of b atom and this sp orbital of a atom will also form covalent bond
with s orbital of this b atom so this is now ssp bond and this is also ssp bond now we can say that
a atom form ssp bond with b atom which is possible understandable and 100 percent right
also remember that hybridization of atomic orbitals does not take place in every molecule
for example no hybridization occurs in the atomic orbitals of molecules
like h2 hcl h2s etc now let me explain the hybridization of atomic orbitals of carbon
firstly learning sp3 hybridization of a carbon atom sp3 hybridization means that in this mixture
of atomic orbitals there is one s orbital and three p orbitals so there are total four orbitals
present in sp3 hybridization here is 25 percent s character and 75 percent peak character
present in the sp3 hybridization now have 1s and 3p orbitals combined together to form
sp3 hybridization for example consider a carbon atom in the ground state we know that there are
six electrons present in carbon atom and one is there are two electrons and two s there are two
electrons while n2p there is one electron in the x orbital and one electron in the y orbital now
let's consider the excited state of a carbon atom there are two electrons in the 1s orbital
while the one electron and 2s jump into z orbital of 2pe this is the excited state of a carbon atom
the 1s orbital is already complete having 2 electrons so this 2s orbital and 3 orbitals of 2p
x y z mix are combined together to form four hybrid orbitals thus i will place these unpaired
four electrons in these four hybrid orbitals remember that they must have the same spin
this is the first sp3 orbital this is the second sp3 orbital this is the third sp3 orbital and
this is the fourth sp3 orbital so we have four hybrid orbitals sp3 each having one electron
now it is sp3 hybridization that teach us the geometry of carbon and its molecule
for example carbon has this type of geometry and sp3 hybridization this is one sp3 orbital
this secant third and fourth sp3 orbitals and each orbital having single electron the bond angle in
sp3 hybridization is 109.5 degree and the ship of sp3 hybridization of carbon is tetrahedral
noted down that these four sp3 hybrid orbitals are called degenerate orbitals it means that
they all have the same energy also let me give you an example of sp3 hybridization
of a carbon and a molecule like methane ch4 now consider sp3 hybridization in this carbon atom
we know that there are four unpaired electrons present in it according to valence bond theory rvt
unpaired electrons are needed to form covalent bond so four hydrogen atoms
will share their single valence electron with the electron of hybrid orbitals of a carbon
and we get ch4 thus this is the shape and geometry of methane ch4 in which carbon has
sp3 hybridization so note down this example secondly let me teach you sp2 hybridization
sp2 hybridization means that in this mixture of atomic orbitals there is one s orbital and two
p orbitals hence there are total three orbitals present in sp2 hybridization
or there is 33 percent s character and 67 percent peak character present in sp2 hybridization
now how these orbitals 1s and 2s combine together in sp2 hybridization well again consider carbon in
a ground state we know that 1s has 2 electrons 2s has 2 electrons and in 2p there is one electron in
x orbital and one electron in y orbital while an excited state of carbon 1s has two electrons
2s has one electron and n2p there is one electron in x orbital one electron in y orbital and one
electron in z orbital now in the hybrid state there are already two electrons present in the
1s orbital we know that in sp2 hybridization 1s orbital and 2 p orbitals combined together so this
2s orbital x and y orbitals of 2p would combine together to form 3 orbitals of sp2 hybridization
thus i will put this unpaired electron in these hybrid orbitals having same spin this
is the first sp2 orbital this is the second sp2 orbital and this is the third sp2 orbital
lastly i write this z orbital of 2p here this z orbital is unhybrid orbital
it means that this c orbital do not combine with 2s 2px and 2py also it has more energy than
all these three hybrid orbitals now carbon has this type of geometry and sp2 hybridization
this is the first sp2 orbital this is the second and third sp2 orbitals while this long orbital
is the 2pz orbital which is unhybridized orbital these all orbitals have one electron each remember
that the bond angle in sp2 hybridization is 120 degree while the shape of carbon is trigonal also
let me give you an example of sp2 hybridization of carbon in a molecule like ethane let's consider
sp2 hybridization in this carbon atom and in this carbon atom firstly both the carbon
atoms will form chemical bond by sharing the unpaired electrons in these spsp orbitals
secondly they both will share the unpaired electrons and unhybrid orbitals to pz
then hydrogen will share its one electron with this sp2 orbital and with this sp2 orbital
also hydrogen will share its electron with this sp2 orbital and with this sp2 orbital
note it down that unhybrid orbitals always form pi bond for example this 2pz form pi bond
while hybrid orbitals always form sigma bond for example these sp2 orbitals form sigma bond
thus in ethane there is one pi bond and one sigma bond between carbon-carbon atoms hence this is the
shape and geometry of a molecule in which carbon has sp2 hybridization so noted down this example
finally let me teach you sp hybridization sp hybridization means that in this mixture of
atomic orbitals there is one orbital of s and one orbital of b present in it so there are total two
orbitals present in sp hybridization there is 50 percent s character and 50 percent p
character in it know how one is orbital and one p orbital combine together to form sp hybridization
well again consider carbon in ground state and an excited state we know that
in sp hybridization only 1s and 1p orbitals mix are combined together to form sp hybridization
hence in the excited state 2s orbital and only x orbital of 2p combine together
to form two sp hybrid orbitals this is the first sp orbital and this is the second sp orbital the
y and z orbitals of 2p do not take part in sp hybridization of carbon so they both are
unhybrid orbitals thus we have two hybrid orbitals and sp hybridization each having unpaired electron
now carbon has this type of geometry and sp hybridization this is the first sp orbital and
this is the second sp orbital while this long orbital is 2py and this long orbital is too pc
they both are unhybrid orbitals the bond angle of sp hybridization is 180 degree
and its ship is linear also let me give you an example of sp hybridization of carbon
and a molecule like ethane let's consider sp hybridization in this carbon and in this carbon
firstly both the carbon atoms will shear the unpaired electrons in spsp orbitals to form a
chemical bond secondly they both will share the unpaired electrons in unhybrid orbitals like 2py
and 2pz to form a chemical bond then hydrogen will share its one electron with this sp orbital
and with this sp orbital there are two unhybrid orbitals like 2py and 2pz joined between carbon
atoms so there are two pi bonds present in ethyne while there is one hybrid orbital
joined between carbon atoms so there is only one sigma bond present in ethane hence this is the
shape and geometry of a molecule and which carbon has sp hybridization just noted down this example