Ethene belongs to class of unsaturated hydrocarbons called as Alkenes. Alkene contains a double bond between two carbon atoms. And the general formula for alkene is,
CnH2n
Whereas in Ethene, n = 2, so
C₂H₄
Therefore, in ethene there are two carbon atoms doubly bonded to each other via one sigma and one pi bond. Also each carbon atom is further covalently bonded to two hydrogen atoms via sigma bond as shown below,