Draw the VESPR structures for 14.1.1

Include bond angles, names of shapes

Bonding AHL

• Describe sigma and pi bonds

• Explain hybridization in terms of sp sp2 sp3

• Explain relationship between Lewis structure, shape and hybridisation

Sigma Bonds

• Sigma bonds are all single bonds, and result from axial overlap of orbitals.

π Bonds

• Result from sideways overlap of parallel p orbitals

Basics

• A single bond is a SIGMA bond

• A double bond is ONE SIGMA ONE PI

• A triple bond is ONE SIGMA TWO PI

Hybridisation – sp3

Hybridisation – sp2

Hybridisation - sp

Homework Task

• Using the following molecules create a student help sheet to explain the bonding, the shape, the hybridisation, and number of sigma and pi bonds.

• In Carbon Dioxide, Methane and Propene.

Geometry and Hybridisation

• All you have to do is count the negative centres, and don’t forget lone pairs

• Inorganic :• 4 negative centres is sp3, e.g. NF3 ( 3bp 1nbp in this case )

• 3 negative centres is sp2, e.g. BF3 ( 3bp in this case )

• 2 negative centres if sp

• Organic : • sp3 is Td 109.5, e.g. Alkanes• sp2 is Trig Pl 120, e.g. Alkenes, Carbonyl groups• sp is lin 180, e.g. Alkynes

Starter

• Explain how sp2 hybridization arises

• Use electrons in boxes notation to explain your answer.

When electron pairs are not confined to two adjacent bonding atoms but extend over 3 or more atoms

Benzene Facts

• Planar regular hexagon

• All bond angles 120 degrees

• Bond lengths intermediate between single and double bonds

• Reluctant to undergo addition reactions.

Nitrate Ion

Nitrite Ion Resonance Structures ?

Carbonate Anion

Ozone

Ethanoate

Learning Check

• N01/420/H(2) part (a) ONLY