14.2 - Hybridisation

We're used to thinking of single bond as sigma bonds.

And we tend to think of those as overlapping s orbitals.

But this can't always be true.

Methane, CH₄, has four equal C-H bonds and the molecule's shape is ________________.

But Carbon atoms only have one s orbital in their valence shell.

For the four bonds to be equal the 2s and 2p orbitals must merge into a hybrid - an orbital that takes some of its shape and character from the s and some from the p.

Carbon has electronic configuration ____________________________

Only the electrons in shell 2 can be involved in bonding but for this to happen 4 unpaired electrons are needed.

But these orbitals are not all equal energy and the three p orbitals are at ________^o so couldn't form, a tetrahedron with a bond angle of ______^o.

So they merge to make 4 equal sp³ orbitals.

What are sp³ orbitals like?

Their character must be _____% like p orbitals, and ______% like an s orbital.

In Ethene, C₂H₄, each Carbon atom has 3 sigma bonds (1 C-C, 2 C-H) and a C-C pi bond and the molecule's shape is ________________.

The pi bond is an overlap of p-orbitals,

Carbon's electronic configuration still needs changing from

to

This time we only need to merge the s orbital with 2 of the p orbitals to allow for 3 sigma bonds

The hybrid orbitals will be called _____________

Their character must be _______% like p orbitals, and _______% like an s orbital.

Ethyne, C₂H₂, contains a Carbon-Carbon Triple bond.

So, each Carbon atom has 2 sigma bonds (1 C-C, 1 C-H) and 2 C-C pi bond and the molecule's shape is ________________.

The two pi bonds need 2 p-orbitals but this means Carbon's electronic configuration still needs changing from

to

This time we only need to merge the s orbital with 1 of the p orbitals to allow for 2 sigma bonds

The hybrid orbitals will be called _____________

Their character must be _______% like p orbitals, and _______% like an s orbital.

Work out the hybridisation in Ammonia, NH₃.

Electronic configuration of central N atom: 1s² 2s² 2p³

Number and types of bond pairs and lone pairs: 3 equal sigma bonds and 1 lone pair

Shape of molecule: Tetrahedral based but pyramidal

This means hybridisation must be __________________

Work out the hybridisation of the Oxygen atom in Ethanol, CH₃CH₂OH.

Electronic configuration of O atom: 1s² 2s² 2p⁴

Number and types of bond pairs and lone pairs: 2 sigma bonds & 2 lone pairs

Shape of molecule: Tetrahedral based but bent

This means hybridisation must be __________________

Work out the hybridisation of the Carbon atom in CO₂

Electronic configuration of C atom: 1s² 2s² 2p²

Number and types of bond pairs and lone pairs: 2 C-O sigma bonds & 2 C-O pi bonds

Shape of molecule: Linear

Number of p orbitals used in pi bonds _______________

This means hybridisation must be __________________

Work out the hybridisation of the Oxygen atom in CO₂

Electronic configuration of O atom: ____________

Number and types of bond pairs and lone pairs: __________________________

Shape of molecule: Linear

Number of p orbitals used in pi bonds ______________

This means hybridisation must be __________________

QUESTION: What is the Hybridisation of the N atom in phenylamine? What is the hybridisation of the C atoms (assume the ring to be made of alternating double and single bonds as in the diagram)