FIGURE 4.23 The pattern of bonding
in ethyne (acetylene). The carbon
atoms are sp hybridized, and the two
remaining p-orbitals on each C atom
form two -bonds. (a) The resulting
pattern is very similar to that for N2
(Fig. 4.12), but C¬H groups replace
the two N atoms. (b) Although the two
-orbitals are built from p-orbitals, the
overall electron density turns out to
have cylindrical symmetry