Hybridization Summary PDF

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What you need to understand: Hybridization of atomic orbitals The formation of a set of hybrid orbitals with favourable directional characteristics by mixing together two or more valence orbitals of the same atom (page 179, 641) e.g. sp3 hybrids

Why do we need “hybrid” orbitals? It is clear that molecules have particular 3dimensional shapes in space. These shapes cannot be simply described by just overlapping the basic s, p (and d) orbitals as the angles which result are not those observed experimentally. So, we need to consider another way to explain the experimental observation – we use (construct mathematically) hybrid orbitals.

A really good web site for explaining hybridization is : http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/hybrv18.swf but a “google” search will turn up many sites (of varying quality) covering the topic of hybridization.

Other important concepts:-

The sigma (σ) bond. A bond formed by end-on overlap of atomic orbitals, giving electron density that is concentrated along the bond axis (page 157) The pi (π) bond. A bond formed by the sideways overlap of two parallel p orbitals. Pi bonds result from the concentration of electron density above and below the bond axis and exhibit binodal planar symmetry.

A pi bond is a region of space in which you can find the two electrons which make up the bond. Those two electrons can live anywhere within that space. It would be quite misleading to think of one living in the top and the other in the bottom.

Describe the structure of N2 using the appropriate hybrid orbitals. Lewis Structure of N2 – triple bond

N2 2XN 1s

2s

2px

2py

2pz

Remove valence electrons N2 is a linear molecule which requires 2 sp hybridised orbitals:

2s

2px

2py

2pz

Hybridise orbitals

sp

sp

2py 2pz Replace electrons

2py

2pz

ONE OF YOUR sp HYBRID ORBITALS CONTAINS A LONE PAIR OF ELECTRONS

hybrid picture of N2

2pz

2py

2pz

2py

1 σ and 2 π bonds = a triple bond What you need to be able to do: Given a molecule you need to be able to construct the Lewis structure and determine the formal charges on each atom. Given this, you need then to be able to decide which is the most probable Lewis Structure. In addition, you need to be able to draw a Lewis structure for a molecule, decide if resonance structures are possible and draw all possible resonance structures. You need then to be able to, using VSEPR, decide on the most likely (stable) 3dimensional shape for the molecule. Given all this information, you should be able to decide what type of hybrid orbitals are most appropriate, how many double bonds are present in the molecule, and then be able to construct the hybrid picture of the molecule....