OAT Organic Chemistry Chapter 41: Bonding

Bonding orbital

is formed when the two atomic orbitals being added together have wave functions with the same sign

Antibonding orbital

is formed when the two atomic orbitals being added together have wave functions with different signs

Sigma (σ) bond

the resulting bond when a molecular orbital is formed by head-to-head overlap*all single bonds are sigma bonds and contain 2 electrons*shorter single bonds are stronger than longer single bonds

Pi (π) bond

bonding molecular orbital that results when two p orbitals overlap in a parallel fashion*the overlap of the p orbitals involved in a pi bond prevents rotation about double and triple bonds*contain two electrons each*CANNOT EXIST INDEPENDENTLY OF A SIGMA BOND*weaker than sigma bonds

Double bond

when both a sigma bond and a pi bond exist between two atoms

Triple bond

when a sigma bond and two pi bonds exist


*if one s orbital and three p orbitals are mathematically combined, the result is four identical sp^3 hybrid orbitals that have a new shape*(ex. CH4) these four orbitals will point toward the vertices of a tetrahedron, minimizing repulsion*the hybridization is accomplished by promoting one of the 2s electrons into the 2pz orbital*this produced four valence orbitals, each with one electron, which can be mathematically mixed to create hybrids


*if one s orbital and two p orbitals are mixed, three identical sp^2 hybrid orbitals are obtained *(ex. H2C=CH2) the third p orbital of each carbon atom is left unhybridized and participates in the pi bond*the three sp^2 orbitals are 120° apart, allowing maximum separation*these orbitals participate in the formation of the C=C and C-H sigma bonds


*if two p orbitals are used to form the pi bond of a triple bond and the remaining p orbital is mixed with an s orbital, two identical sp hybrid orbitals are obtained *(ex. HC≡CH) the remaining two p orbitals of each carbon atom are left unhybridized and participate in creating two pi bonds, resulting in a triple bond *the two sp hybrid orbitals are oriented 180° apart, explaining the linear structure of molecules

Formal charge formula

N - (# of sticks) - # of balls

Order of free radical stability