Organic Structures - Organic Chemistry Concepts: An EFL Approach - page 6

FIGURE 1.4
sp 2 -hybridized carbon (trigonal, 3 σ + 1 π bonds).
FIGURE 1.5
sp -hybridized carbon (linear, 2 σ + 2 π bonds).
Because the s orbital is lower in energy and closer to the nucleus than p orbital,
hybrid orbitals with a greater percentage of s character form shorter, stronger
bonds. Also, as the s orbital content increases, both the bond length and bond
energy decrease.
Hybridization must give the same number of new hybrid atomic orbitals
as the number of original atomic orbitals that are combined.