Final answer:
The first ethene Lewis structure is incorrect because it violates the octet rule. The correct Lewis structure for ethene shows a double bond between the carbon atoms, where one bond is a sigma bond and the other is a pi bond.
Step-by-step explanation:
The first ethene Lewis structure is incorrect because it contains a total of 14 electrons instead of the correct number of 12 electrons. In the incorrect structure, each carbon atom has one lone pair of electrons, which makes it exceed its octet. However, the correct Lewis structure for ethene can be drawn by eliminating the lone pairs on the carbon atoms and having the carbon atoms share two pairs of electrons, instead of only one pair.
The correct Lewis structure for ethene shows a double bond between the two carbon atoms, represented by a double dash. It is important to note that the two bonds in a double bond are different: one is a sigma bond and the other is a pi bond. The sigma bond is formed by the overlap of two hybridized orbitals, while the pi bond is formed by the overlap of two unhybridized p orbitals.
Overall, the first ethene Lewis structure is incorrect because it violates the octet rule, but it can be corrected by appropriately sharing electrons between the carbon atoms in the molecule.