Methene do not exist in nature. This is because the alkene family have the general formula C n H 2n where n is a natural number(which starts from 1). If we substitute 1 in place of n, then we get the formula CH2. CH2 has no independent existence, as the tetravalent nature of carbon is being violated.To have a double bond you need at least two atoms, so ethene is the smallest possible alkene.
