Question

1.) Using valence bond theory, describe the bonding in acetylene. Your description must include the type of each of the five bonds and the orbital each atom is using to form each of the bonds.

Answer 1

In acetylene molecule both the carbon atoms are sp hybridised.Each carbon atom has two sp hybrid orbitals. one sp hybrid orbital is used to overlap with sp hybrid orbital of adjacent carbon atom to form one sigma bond between the carbon atoms. Remaining sp hybrid orbital of each carbon overlaps with s-orbital of hydrogen atom to form sigma bond with hydrogen atom.

Each carbon atom has two unhybridized p-orbtials which lie perpendicular to the axis of molecule. They overlap with each other through side ways to form two pi-bonds