Hybridization in Organic Chemistry: sp3, sp2, and sp Explained

[00:00:00]Students, this video is about a very important topic of organic chemistry called hybridization.

[00:00:05]Some students find this topic a little bit difficult, but I hope this video will help you in getting a clear idea of this topic in your mind. So, let's get started. First of all, you must know what an orbital is. Atomic orbitals are regions of space around the nucleus of an atom when an electron is likely to be found. So, orbitals, they're the regions or areas around the nucleus where an electron is present.

[00:00:27]Orbitals are also known as energy levels. These are the different types of orbitals and they have different energies and different shapes as you can see. S orbital can accommodate two electrons at maximum. P can accommodate six, D can accommodate 10 and F can accommodate 14 electrons. So these are the different orbitals and they have different shapes and energies. And orbitals they are the region around the nucleus where an electron is likely to be found. Now hybridization it's the mixing of atomic orbitals into new hybrid orbitals with different energies and shapes than the component atomic orbitals and they're suitable for pairing of electrons to form chemical bonds.

[00:01:06]By the pairing of electrons the stability is gained and a chemical bond is formed. Now student whenever the word bond comes it means that it's a force that binds atoms or ions in a molecule or a crystal. So bond it's a force that binds atoms or ions together and hybridization it's the mixing of atomic orbitals which results in the formation of hybrid orbitals and they have different shapes and energies than the original atomic orbitals. Now this is carbon and carbon is the head of the fourth group of the periodic table.

[00:01:36]Carbon, silicon, geranium, tin and lead.

[00:01:39]This is the fourth group. I keep on repeating the elements of the periodic table because learning periodic table makes chemistry concepts very easy for you.

[00:01:50]Now this is the carbon ground state electronic configuration. As carbon is in the fourth group, it has four veence electrons and it has six atomic numbers.

[00:01:58]So six electrons, six protons. The ground state has 1 s2, 2 s2 and 2p2. The 2pz orbital is empty and the carbon in the excited state electronic configuration is 1 s2 and the one of the electron from the 2s orbital it jumps from the 2s orbital into the empty 2pz orbital. Now there are four unpaired electrons in the veence shell.

[00:02:21]So this is also carbon atom. Two electrons in the inner shell and four in the outer shell that is the veence shell.

[00:02:27]Although the most stable electronic configuration of a carbon atom having two partially filled 2p orbitals requires it to be dvalent. Carbon is tetraalent in the majority of its compounds. In order to explain this apparent anomaly, it is assumed that an electron from the 2s orbital it is promoted to an empty 2pz orbital given electronic configuration of 2s1 and 2p3 in the veence shell. As you can see here the excited state configuration can explain the tetra valency of carbon. But these four valencies will not be equivalent. As you can see one is 2s orbital and the other is 2p orbital.

[00:03:06]These two have different energy levels.

[00:03:08]So orbital hybridization theory has been developed to explain the equivalent tetravalency of carbon. According to this theory, the four atomic orbitals of the carbon belonging to veence shell may be mixed in different ways to explain the bonding and shapes of molecules formed by carbon atoms.

[00:03:26]Generally there are three types of hybridization sp3, sp2 and sp.

[00:03:31]Sp3 hybridization is observed in saturated compounds and sp and sp2 this is observed in unsaturated compounds.

[00:03:39]Now the name indicates in sp3 hybridization it is the mixing of 1 s and 3 p orbitals 1 ss and 3 p orbitals and the formation of four hybrid orbitals.

[00:03:50]All the four hybrid orbitals they are degenerate that is they have same energy and same shape but they don't lie in the same plane. They have tetrahedral geometry and the bond angle between the hybrid orbitals is 109.5.

[00:04:04]So 109.5 it is the bond angle.

[00:04:09]In sp3 hybridization four sigma bonds are formed and the sigma bonds are formed by the direct overlap of the atomic orbitals and again they are observed this type of hybridization is observed in the saturated compounds having single bonds. Now this is the diagrammatical representation of sp3 hybridization. In order to explain the bonding and shapes of molecules in which carbon is attached with four atoms, all these four orbitals are mixed together to give rise to four new equivalent hybrid orbitals having same shape and energy. As you can see here, 1s and 3p orbital they mix together to form four sp3 hybrid orbitals and they degenerate having same shape and same energy.

[00:04:50]This mode of hybridization is called tetrahedral and sp3 hybridization.

[00:04:54]All these four hybrid orbitals they degenerate and are directed at an angle of 109.5 in space to give tetrahedral geometry. As you can see here, when a carbon atom forms single bonds with other atoms, the hybrid orbitals overlap with the orbitals of these atoms to form four sigma bonds 1 2 3 4. Four sigma bonds. This type of hybridization explains the bonding and shapes of all those compounds in which carbon atom is saturated.

[00:05:24]In this tetrahedral geometry, one of the carbon is above the plane and the other is below the plane. It is not co-planer.

[00:05:33]The example is of methane which is CH4.

[00:05:35]You can see here the carbon is tetrahedral. The hydrogen's four hydrogen's are approaching towards the sp3 hybrid carbon and four CH bonds are formed.

[00:05:48]So the four hybrid atomic orbitals of carbon overlap separately with four 1s orbital of the hydrogen to form four equivalent CH bonds. As you can see here the shape of methane is tetrahedral and all the four hydrogen atoms they do not lie in the same plane. One is above the plane and one is below the plane. So this is the methane molecule.

[00:06:14]Now this is ethane. There are two carbon atoms. Etha means two carbon atoms.

[00:06:19]C2H6.

[00:06:20]So again each carbon is making four sigma bonds. One is with the one carbon other carbon and the rest of the three bonds they are formed with the three hydrogens. Same is the case with this carbon four sigma bonds.

[00:06:36]So in ethanes the two tetrahedrons of each carbon they are joined together and further addition of a carbon atom with ethane will mean the attachment of another tetrahedron.

[00:06:49]So two tetrahedrons they join together to form ethane.

[00:06:55]Now the question arises from where does the energy come to excite the carbon atom? The answer to this question is very simple. Before excitation the carbon should make two coalent bonds releasing an adequate amount of energy.

[00:07:08]But after excitation however it will form four coalent bonds releasing almost double the amount of energy. This excess energy is more than the needed to excite the carbon atoms. So a tetraalent carbon atom is more stable or is expected to be more stable than a dalent carbon atom.

[00:07:26]The energy released by formation of two additional bonds more than compensates for the excitation energy required.

[00:07:35]Now let's see what sp2 hybridization is.

[00:07:37]It is observed in unsaturated compounds and it is the mixing of 1 s and 2p orbitals. So as a result there is a formation of three hybrid orbitals and the geometry observed in this case is trional and the angle between the hybrid orbital is 120° and this type of hybridization there is a co-planer geometry co-planer they are on the same plane the hybrid orbitals they are on the same plane there's a formation of three sigma bonds and one pi bond sigma bonds are formed by the direct overlap of the atomic orbitals and pi bonds are formed by the parallel overlap of the atomic orbitals the 2pz orbital it is unhybridized and it remains perpendicular to the triangle. Again it is observed in the unsaturated compounds. Now diagrammatically as you can see here there is a mixing of 1 s orbital and 2 p orbital and one of the orbital it remains unchanged and unhybridized. So there is the formation of three hybrid orbitals.

[00:08:34]So in order to explain the bonding and unsaturated compounds there are two more modes that is sp and sp2. The structure of alkenes can be explained by sp2 hybridization. Alkenes ens double bonds.

[00:08:47]In this type 1 2 and 2p orbitals they are mixed together to give three equivalent and co-planer sp2 hybridized orbitals.

[00:09:00]Each sp2 hybrid orbital is it is directed from the center of an equilateral triangle to its three corners. As you can see here, these are the three corners. So this is the trional geometry. The bond angle between any two sp2 hybrid orbital is 120° and the unhybridized 2pz orbital will remain perpendicular to the triangle thus formed. The triangle thus formed the 2pz orbital. It is perpendicular to the triangle. As you can see here the example of sp2 hybridization is ethine ethine C2H4. So there is a double bond and as you can see here three sp2 orbitals of each carbon atom overlap separately with sp2 orbital of another carbon atom and 1s orbitals of two hydrogen atoms to form three sigma bonds as you can see here 1 2 3. So three sigma bonds are formed and with the other carbon again 1 2 3 three sigma bonds are formed.

[00:10:09]The unhybridized orbital of each carbon atom will then overlap in a parallel fashion to form a pi bond. These are the unhybridized orbitals and they are overlapping in a parallel fashion to form pi bonds. So this double bond is the pi bond and the rest of the single bonds are the sigma bonds. So this is the ethine molecule.

[00:10:30]Now let's see the sp hybridization.

[00:10:33]Again it is observed in the unsaturated compounds and it is the mixing up of 1 S and 1 P orbital and there's the formation of two hybrid orbitals. The geometry is linear that is straight and the angle between them is 180°.

[00:10:50]There's the formation of two sigma bonds and two pi bonds. Again two sigma bonds and two pi bonds. the two unhybridized orbitals that is the 2pz and 2py orbital they remain perpendicular to the sp hybridized orbitals.

[00:11:06]Now this is the diagrammatical representation of sp hybridization.

[00:11:11]The structure of alkyes ions that is the triple bonds they can be explained by yet another mode of hybridization called sp hybridization.

[00:11:19]In this type 1 2 S and one 2p orbital of the carbon atom mixed together to give rise to two degenerate sp hybridized atoms or atomic orbitals and these orbitals have linear shape with bond angle of 180°. As you can see here they are linear and they have an bond angle of 180°.

[00:11:41]Now this is the example acetylene or ethine. As you can see two carbons and there is a triple bond.

[00:11:50]This is the ground state. This is the excited state and two 1 s and one p that is the two orbital they join together or they mix together to give rise to two hybrid orbitals and the two remain unhybridized.

[00:12:05]These are the sp hybrid orbital and these are the unhybridized orbital and then the pairing occurs. So there is a formation of two sigma bonds and two pi bonds. So these are the two pi bonds and one of the sigma bond is with carbon and the other is with the hydrogen.

[00:12:23]As here it is clearly explained this is the ethine molecule that is the alkine.

[00:12:30]This is the ethine that is the triple bond.

[00:12:34]Now in this case the ethine molecule is formed when two sp hybridized carbon atoms join together to form a sigma bond by sp overlap. Here you can see that there is a sigma bond and there is an sp overlap and the other sp orbital is utilized to form sigma bond with the 1s orbital of hydrogen atom. This is the hydrogen atom and this is a sigma bond with the sp hybrid orbital and this is the sp overlap direct overlap and this is also a sigma bond. So this is the carbon carbon sigma bond and this is the carbon hydrogen sigma bond. Same is the case with this carbon.

[00:13:16]On the other hand these p orbitals they are overlapping in a parallel fashion. So they are making two pi bonds. This is 2py and this is 2pz.

[00:13:27]Again this is 2p 2pz. are unhybridized.

[00:13:30]They are perpendicular to the hybrid sp orbitals and they are making pi bonds.

[00:13:37]So there are two pi bonds and two sigma bonds of each carbon atom. So this is the example of ethine.

[00:13:50]This is a summary of hybridization.

[00:13:53]If the number of electron domains that is the orbitals are two this is sp hybridization. If the number of electron domains is three, this is sp2 hybridization. And if the number of domains electron domains is four, this is sp3 hybridization. Now you can see here this is the linear geometry. This is the trional geometry and this is the tetrahedral geometry. These are the drawings of hybrid orbitals.

[00:14:18]And students, you must keep it in mind that in the case of SP, the presence of a sigma and two pi bonds between two carbon atoms is responsible for the shortening of bond distance. So bond distance is shortened in this case. This is the sp hybrid orbital. This is the sp2 and this is the sp3 linear trional and tetrahedral.

[00:14:43]180° bond angle, 120° bond angle, and 109.5° bond angle. I hope this video was helpful. If you like this video, please like, share, comment, and subscribe.

[00:14:54]Thanks for watching. Wish you all the best.