Question -
Answer -
C2H4 :
The electronicconfiguration of C-atom in the excited state is:
In the formation of an ethane molecule (C2H4), one sp2 hybrid orbital ofcarbon overlaps a sp2 hybridized orbitalof another carbon atom, thereby forming a C-C sigma bond.
The remaining two sp2 orbitals of eachcarbon atom form a sp2–s sigma bondwith two hydrogen atoms. The unhybridized orbital of one carbon atom undergoessidewise overlap with the orbital of a similar kind present on another carbonatom to form a weak π-bond.
C2H2 :
In the formation of C2H2 molecule, eachC–atom is sp hybridized with two 2p-orbitals in anunhybridized state.
One sp orbital of eachcarbon atom overlaps with the other along the internuclear axis forming a C–Csigma bond. The second sp orbital of each C–atom overlaps ahalf-filled 1s-orbital to form a σ bond.
The two unhybridized 2p-orbitals ofthe first carbon undergo sidewise overlap with the 2p orbital ofanother carbon atom, thereby forming two pi (π) bonds between carbon atoms.Hence, the triple bond between two carbon atoms is made up of one sigma and twoπ-bonds.
