'You have already read that the pi (π) bond is a weaker bond due to poor sideways overlapping between the two 2p orbitals."

1 pie bond is actually 2 bonds as it need 2 p orbitals

1 hour ago, HbWhi5F said:

'You have already read that the pi (π) bond is a weaker bond due to poor sideways overlapping between the two 2p orbitals."

1 pie bond is actually 2 bonds as it need 2 p orbitals

OK, it's not "pie", it is "pi", the English for the Greek letter π.

The π bond involves one, repeat one, orbital on each carbon atom, and contains one pair of electrons. It is not regarded as two bonds. A double bond consists of one σ bond and one π bond. However the π bond does have 2 lobes of electron density, one above and one below the axis of the σ bond. That is because it formed by the sideways overlap of a dumbell-shaped orbital on each atom, like this: 8-8.

@exchemist thanks

Double bond use 2p orbitals per C atom in C-C double bond and also in triple bond how ?

Book also says " Each carbon has two unhybridized p orbitals which are perpendicular to each other as well as to the plane of the C-C sigma bond." which means p orbital has 2 lobes ?

@exchemist

Edited October 27Oct 27 by HbWhi5F

26 minutes ago, HbWhi5F said:

Double bond use 2p orbitals per C atom in C-C double bond and also in triple bond how ?

Book also says " Each carbon has two unhybridized p orbitals which are perpendicular to each other as well as to the plane of the C-C sigma bond." which means p orbital has 2 lobes ?

@exchemist

Because it is sp hybridised instead of sp2. That means s and pz are hybridised (if we take the z axis as being along the line of the bond), leaving both the px and py to overlap sideways on, 8-8 style, as I explained before, but at right angles to one another. This is actually shown in the diagram.

what does having x2 sp hybridized orbital mean ?

In C-C triple bond x2 sp hybridized orbitals are formed,

but in questions earlier it has taught that 1 sigma bond = s, 2 = sp, 3 = sp2

Edited October 27Oct 27 by HbWhi5F

5 minutes ago, HbWhi5F said:

what does having x2 sp hybridized orbital mean ?

In C-C triple bond x2 sp hybridized orbitals are formed,

but in questions earlier it has taught that 1 sigma bond = s, 2 = sp, 3 = sp2

No. The px and py orbitals are unhybridised in a triple bond. It is the unhybridised p orbitals that form π-bonds.

In the carbon atoms on acetylene, H-C≡C-H, each has two σ-bonds at 180 degrees to each other, formed by the sp hybridised orbitals. One of these is to the H atom at the end of the molecule, and the other is between the 2 carbon atoms. That leaves 2 unhybridised p orbitals to overlap sideways on in 8-8 formation, making 2 π-bonds. In summary:

sp hybridisation of a carbon atom gives 2 σ-bonds at 180 deg to one another, in a (1D) line. That leaves 2 unhybridised p orbitals to form 2 π-bonds.

sp2 gives 3 σ-bonds at 120 deg to one another, in a 2D plane. That leaves 1 unhybridised p orbital to form a π-bond.

sp3 gives 4 σ-bonds at 109.5 deg to one another, in a 3D tetrahedron. That leaves no p orbital unhybridised, so no π-bonds.