Hybridization

Section 14.2

Introduction

A hybrid results from combining 2 of the same type of object and it has characteristics of both

Atomic orbitals undergo hybridization during bonding

Consider the methane molecule, CH4

The electron configuration of C is 1s22s22p2

You might expect the two unpaired p electrons to bond with other atoms and the 2s electrons to remain as a lone pair

Visual

Carbon Hybridization

This does not happen as we know carbon forms 4 bonds

Hybridization: a process in which atomic orbitals are mixed to form new, identical hybrid orbitals

Each hybrid orbital contains one electron that it can share with another atom

Carbon

One s and three p orbitals hybridize to form four sp3 orbitals

Shape

According to VSEPR, a tetrahedral shape minimizes repulsion between the orbitals

sp3 orbitals

Another Hybrid

Consider BF3

There are three total pairs of electrons with three shared pairs

VSEPR predicts a trigonal planar shape To have this shape, one s and two p orbitals on

the B must mix to form 3 identical sp2 hybrid orbitals

Note that one p orbital is unoccupied

Visual

Another Hybrid

Consider BeF2

Electron configuration of Be is 1s22s2

Be must promote one electron to the 2p orbital Results in sp hybridization and a linear shape

More Information

Lone pairs can occupy hybrid orbitals Consider water: It forms sp3 hybrid orbitals and

the two lone pairs on the oxygen atom are in two of the hybrid orbitals

Look at the total number of areas of electron density on the central atom to discover the type of hybrid orbital

4 centers: sp3, 3 centers: sp2, 2 centers: sp

Organic Molecules

Consider ethane (C2H

6), ethene (C

2H

4) and

ethyne (C2H

2)

Decide which type of hybridization each carbon has

Look on the board for drawings of these structures

Ethane: sp3, ethene: sp2, ethyne:sp

Sigma Bond (σ)

Sigma bond: occurs when the electron pair is shared in an area centered between the two atoms

The atomic orbitals (could be hybrids) overlap end to end

Electron density is at its greatest on the inter-nuclear axis (an imaginary line joining the two nuclei

Single bonds are sigma bonds

Visual of Sigma Bond

Pi Bond (π)

Pi bond: is formed when parallel orbitals overlap to share electrons

High electron density is found above and below the inter-nuclear axis (not on it)

A double bond consists of one sigma bond and one pi bond

A triple bond consists of one sigma bond and two pi bonds

Visual of Pi Bond