which the 2s combines with one p(sp). The geometry predicted for the sp hybrid is trigonal with the unused p-orbital perpendicular to the plane. Carbons which are sp must be connected to at least one additional sp? atom and organic molecules containing one or more pairs of sp carbons are called alkenes. A model for the simplest alkene, ethene (or ethylene) is shown below. As the drawing shows, the hydrogens and the second carbon are attached to the sp: carbon by 120 bond angles. The p-orbital on each of the sp carbons each contain one electron ("split"between the top and bottom lobes)and the two adjacent p-orbitals are in a position to overlap with each other to form a T-bond in which electron density is concentrated between the atoms, in a diffuse orbital above and below the plane. The combination of the single bond, formed from the sp orbitals, and the T-bond, are represented as a carbon-carbon double bond. In this representation, the valence of carbon is still four, with the double bond counting for two. The final hybrid which is common in organic chemistry is constructed from one s- and one p-orbital, termed an sp-hybrid and has linear geometry, as shown below. The two remaining p-orbitals on each sp atom each participate in T-bond formation with an adjacent sp center and form a triple bond; one sigma bond and two T-bonds. The three types of hybridization which are encountered in carbon compounds are shown below for the molecules ethane (sp, an alkane), ethene (sp, an alkene) and ethyne(sp, an alkyne) in both ball-and-stick and space-filling format. 〈,which the 2s combines with one p (sp). The geometry predicted for the sp2 hybrid is trigonal with the unused p-orbital perpendicular to the plane. Carbons which are sp2 must be connected to at least one additional sp2 atom and organic molecules containing one or more pairs of sp2 carbons are called alkenes. A model for the simplest alkene, ethene (or ethylene) is shown below. As the drawing shows, the hydrogens and the second carbon are attached to the sp2 carbon by 120o bond angles. The p-orbital on each of the sp2 carbons each contain one electron ("split" between the top and bottom lobes) and the two adjacent p-orbitals are in a position to overlap with each other to form a -bond in which electron density is concentrated between the atoms, in a diffuse orbital above and below the plane. The combination of the single bond, formed from the sp2 orbitals, and the -bond, are represented as a carbon-carbon double bond. In this representation, the valence of carbon is still four, with the double bond counting for two. The final hybrid which is common in organic chemistry is constructed from one s- and one p-orbital, termed an sp-hybrid, and has linear geometry, as shown below. The two remaining p-orbitals on each sp atom each participate in -bond formation with an adjacent sp center and form a "triple bond"; one sigma bond and two -bonds. The three types of hybridization which are encountered in carbon compounds are shown below for the molecules ethane (sp3, an alkane), ethene (sp2, an alkene) and ethyne (sp, an alkyne) in both ball-and-stick and space-filling format