CHAP 9Hybridization of Orbitals

What is Hybridization?

• Mixing of native orbitals to form special bonding orbitals

• Modifies the “localized electron model” (aka Lewis Structure) to show special atomic orbitals used in forming molecules• Orbitals can overlap to form the bonds – helps with the electron sharing

• Combinations of s, p, & d orbitals• Bonding primarily involves the valance electrons, which comes from the s or p orbitals

Types of hybridization

sp3 hybridization: combination of 1-s and 3-p orbitals

4 sp3 hybrid orbitals

4 pairs e- around center atom

tetrahedral or triangular pyramid

sp2 hybridization: combination of 1-s and 2-p orbitals

3 sp2 hybrid orbitals

3 pairs e- around center atom

trigonal planar

sp hybridization: combination of 1-s and 1-p orbital

2 sp hybrid orbitals

2 pairs e- around center atom

linear

dsp3 hybridization: combination of 1-d, 1-s and 3-p orbitals

5 dsp3 hybrid orbitals

5 pairs e- around center atom

trigonal bipyramidal

d2sp3 hybridization: combination of 2-d,1-s and 3-p orbitals

6 d2sp3 hybrid orbitals

6 pairs e- around center atom

octahedral

Specific covalent bonding

• Sigma (σ) bonds – electrons occupy space directly between atoms (center line)

• Pi (π) bonds - electrons occupy space above or below center line joining atoms

• Single bonds = sigma bonds• Double bonds = 1 sigma & 1 pi bonds• Triple bonds = 1 sigma & 2 pi bonds

Photoelectron spectroscopy (PES)

• Can be used to determine the relative energies of electrons in individual atoms and molecules or ID element

• Photoelectric effect = light shined on metal causes electrons to be ejected/emitted• Higher frequency of light causes more electrons to be

emitted.• Higher frequency = higher energy• E=hν

• binding energy of electrons is determined through PES• High energy incident light (X-ray or UV) is used to eject a

single electron then measure KE of electron• Every “kind” of electron has a binding energy

• subshells

PES continued

• Binding energy = difference between incident light and KE of ejected electron

• When many atoms are hit with incident light, many electrons are emitted. A combined binding energy for the electrons then gets plotted on a photoelectron spectrum.• X-axis = binding energy (ionization energy) (decreases left

to right)• Y-axis = relative number of electrons• One peak for each “kind” of electrons• Peak height corresponds to number of electrons of that

“kind”• As effective nuclear charge increases (number of protons),

the binding energy increases

Each peak corresponds to a set number of electrons. Should correlate with the electron configuration of an element.4 peaks = 4 orbitals in the electron configuration or orbital diagram1s, 2s, 2p, 3s