Why are pi bonds formed?

Question

Sarah Angotti · Accepted Answer

pi bonds are used to form double and triple bonds covalent bonds between atoms

There is only one s orbital in any given energy level. Sharing the S orbital creates only one bond. To make a double bond the p bonds must be used. The sharing of p orbitals creates pi bonds. For example #N2# has three bonds. The triple bond requires the sharing of the one S orbital and two P orbitals . The S orbitals overlap directly forming a covalent bond. The two sets of p orbitals overlap side by side creating the pi bonds, which are also covalent bonds

Ella Allen · Answer

π bonds are formed because the side-by-side overlap of #p# orbitals leads to a lower-energy state than if there were no overlap.

Consider the formation of ethylene, #"H"_2"C=CH"_2#.

The #"C"# atoms are #sp^2# hybridized.

The #"C-C"# σ bond is formed by the overlap of the #"C"# #sp^2# orbitals, and the #"C-H"# σ bonds are formed by the overlap of the #"H"# #1s# orbitals with the #"C"# #sp^2# orbitals.

This leaves an unhybridized p orbital containing one electron on each #"C"# atom.

When you have two #p# orbitals on adjacent #"C"# atoms, they can overlap sideways to form a region of electron density that is not directly between the two nuclear centres but which still contributes to bonding.

We call this a π bond.

It forms because the π electrons are as close as they can get to the two nuclei and are therefore in their lowest energy state.

A π bond can only form only after a σ bond has already formed. It is always part of a double or triple bond.

Zoe Alexander · Answer

undefined Pi bonds are formed due to the overlap of atomic orbitals perpendicular to the internuclear axis. This overlap occurs between p orbitals or between a p orbital and a d orbital, resulting in the formation of a pi bond. Pi bonds contribute to the stability of molecules and are typically found in double or triple bonds. They allow for the sharing of electron density between atoms, thereby facilitating the formation of strong covalent bonds.