CHEM 14A Chapter Notes - Chapter 2F.2: Ethane
6 Dec 2020
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2f. 2 electron promotion and the hybridization of orbitals. Difficulties are encountered when applying vb theory. A carbon atom has four unpaired electrons available for bonding when an electron is promoted. Although the promoted electron enters an orbital of higher energy, it experiences less repulsion from other electrons than before it was promoted. Only a little energy is needed to promote the electron. Nitrogen cant use promotion because it has no empty p-orbitals. Where the wavefunctions are all positive or negative, the amplitudes are increased by this interference. Opposite signs -> overall amplitude is reduced and might be canceled completely. The interference between the atomic orbitals results in new patterns called hybrid orbitals. Hybridization is represented as the formation of four orbitals of equal energy. In the promoted, hybridized atom, each of the electrons in the four sp3 hybrid orbitals can pair with an electron in a hydrogen 1s-orbital. The four electron pairs around each carbon take up a tetrahedral arrangement.
