HYBRID ATOMIC ORBITALS

pure atomic orbitals

Ø Pure orbitals are atomic orbitals that contain electrons
Ø Not hybridized orbitals
Ø Contain the electrons of the atom and undergo chemical bonding to form simple chemical compounds

s orbital

spherical; 2 maximum electrons

p orbital

dumbbell shaped; 6 electrons; 3 orbitals

d orbital

clover shaped; 10 electrons; 5 orbitals

f orbital

daisy shaped; 14 electrons; 7 orbitals

hybridizations

Ø The concept of mixing two or more Pure Atomic Orbitals (PAO) to give rise to a new type of orbitals; results to the formation of Hybrid Atomic Orbitals

equal energies

Atomic orbitals with __________ undergo hybridization

equal

The number of Hybrid Atomic Orbital (HAO) formed is _______ to the number of Pure Atomic Orbitals (PAO) that are mixed

sp3 hybridization

When one 's' orbital and 3 'p' orbitals belonging to the same shell of an atom mix together to form four new equivalent orbitals

sp3 angle

109.5 degrees

sp3 geometry

tetrahedral

sp3 character

25% s, 75% p

sp3 bond order

all single bonds

sp2 hybridization

when one s and two p orbitals of the same shell of an atom mix to form 3 equivalent orbitals

sp2 angle

120 degrees

sp2 geometry

trigonal planar

sp2 character

33% s and 67% p

sp2 bond order

all double bonds; all compounds of boron

sp hybridization

when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals

sp angle

180 degrees

sp geometry

linear

sp character

50% s, 50% p

sp bond order

all triple bonds, all compounds of beryllium

sp3d hybridization

mixing of 1s orbital, 3p orbitals and 1d orbital

sp3d angle

90 degrees vertical, 120 degrees axial

sp3d geometry

trigonal bipyramidal

sp3d character

20% s, 60% p and 20% d

sp3d example

phosphorus pentachloride (PCl5)

sp3d2 hybridization

has 1s, 3p and 2d orbitals

sp3d2 angle

90 degrees

sp3d2 geometry

octahedral

sp3d2 character

16% s, 50% p, 33.33% d

sp3d2 example

sulfur hexafluoride (SF6)

carbon sp3 hybridization

carbon is bonded to four other atoms (with no lone electron pairs)

carbon sp3 geometry

tetrahedral

carbon sp3 angle

109.5 degrees

carbon sp2 hybridization

carbon atom bound to three atoms (two single bonds, one double bond)

carbon sp2 geometry

trigonal planar

carbon sp2 angle

120 degrees

carbon sp hybridization

carbon is bound to two other atoms (two double bonds or one single + one triple bond)

carbon sp geometry

linear

carbon sp angle

180 degrees

nitrogen sp3 hybridization

nitrogen is bonded with three atoms with one lone electron pair that does not participate in the bonding

nitrogen sp3 geometry

trigonal pyramidal

nitrogen sp3 angle

120 degrees

nitrogen sp2 hybridization

two atoms bonded to the Nitrogen (one single and one double bond) and one lone electron pair

nitrogen sp2 geometry

trigonal pyramidal

nitrogen sp2 angle

120 degrees

oxygen sp3 hybridization

oxygen bonded to two atoms and two lone electron pairs

oxygen sp3 geometry

tetrahedral

oxygen sp3 angle

109.5 degrees

sulfur sp3 hybridization

sulfur bonded to two atoms

sulfur sp3 geometry

tetrahedral

sulfur sp3 angle

109.5 degrees

bond length

the average distance between the nuclei of two bonded atoms

factors affecting bond length

a. The bond length increases with increase in the size of the atoms.
b. The bond length decreases with the multiplicity of the bond.
c. The greater the s−character, shorter is the hybrid orbital and hence shorter is the bond length.
d. Polar bond length is usually shorter than the theoretical nonpolar bond length

bond angle

the angle formed by 2 bonds to the same atom; average distance between the bonded orbitals

factors affecting bond angle

a. The Repulsion between atoms or the groups attached to the central atom might increase or decrease the bond angle
b. In the hybridization as the s character of the hybrid increases, bond angle increases
c. By increasing the lone pair of electrons, the bond angle decreases approximately by 2.5%
d. If the electronegativity of central atom decreases, the bond angle decreases.

bond energy/strength

amount of energy required to break a bond

factors affecting bond energy

a. The larger size of the atom, greater is the bond length and less will be the bond dissociation energy which means less is the bond strength
b. For bond between the two similar atoms, greater is multiplicity of the bond, greater will be the bond dissociation energy
c. The greater the number of the lone pairs of electrons present on the bonded atoms, the greater will be the repulsion between the atoms and thus less is the bond energy
d. The bond energy increases as hybrid orbitals have greater % s character
e. The greater electronegativity difference, the greater is the bond polarity and thus greater will be the bond energy

bond order

the number of bonds between atoms: 1 for a single bond, 2 for a double bond, and 3 for a triple bond

resonance bond

occurs when more than one valid lewis structure can be written for a particular molecule; these bonds are shorter and stronger than single bonds but are longer and weaker then double bonds

bond polarity

Ø The polarity of a bond the extent to which it is polar is determined largely by the relative electronegativities of the bonded atoms.
Ø Bond polarity and ionic character increase with an increasing difference in electronegativity

factors affecting bond polarity

a. Nature of Bonded Atoms - the greater the electronegativity difference between 2 bonded atoms, the more polar the bond becomes
b. Type of Hybridization - the higher %s character of the hybrid, the more polar it becomes
c. Formal Charge - positively formal charge molecule is more polar than the corresponding molecule with no charge.
d. Influence of Neighboring Atom - a highly electronegative atom induces the polarity of a neighbored nonpolar covalent bond.