Hybridization Ethene and Alkenes

Three sp2 bonding orbitals are formed from one 2s and two 2p orbitals, The remaining p orbital on each carbon of ethene is used to form the n bond. 

The it bond of alkenes reacts with electrophiles, e.g. bromine. 

The presence of the k bond confers properties on an alkene that mark it out as different from an alkane. In particular, the n bond, by the nature of its sideways overlap of the constituent p orbitals, is weaker than a a bond. Moreover, the electrons of the n bond are relatively exposed, above and below the plane of the alkene. These electrons are the source of reactivity of the alkene toward electrophiles, as in, say, electrophilic addition of bromine (Chapter 4). The n bond in ethene (and other alkenes) is, however, sufficiently strong that it prevents rotation around the carbon-carbon a bond, which is a well-documented property of the carbon-carbon bond in ethane (Section 1.6). The bonding between sp2 

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