1. Finishing off Hybridization
SCH4U1
February 22nd 2011
Mr. Dvorsky

2. Sigma and Pi Bonds
Partial hybridization of the available orbitals is possible –leaving one or two p orbitals with single unpaired electrons
Let us again use carbon as an example:
Instead of mixing all four orbitals, only three are
mixed forming three sp2 hybrid orbitals and an
unhybridized p orbital

4. Sigma and Pi Bonds
In a molecule like C2H4, three hybrid orbitals are used to form single bonds between carbon and hydrogen atoms.
These single bonds are called sigma bonds
All atoms in a molecule are attached by a sigma bond

5. Sigma and Pi Bonds
The half filled p orbital on each carbon overlaps to form a pi bond
It is an area of electron density above and below the sigma bond.
Creates greater force between the two carbon atoms. Double bonds are stronger than single bonds

6. SCH4U1 February 22nd 2011 Mr. Dvorsky
VSEPR Theory
SCH4U1
February 22nd 2011
Mr. Dvorsky

7. Shapes of Molecules
Ionic bonding is nondirectional, which means that ions will attract others of opposite charge with the same force regardless of where these other ions are located around the ion in question.
Covalent bonds are directional, which means for a given central atom there is a preferred orientation for the other atoms attached to it.
Shapes of molecules are important, i.e. Enzymes in biochemical reactions

8. VSEPR Theory
VSEPR -valence shell electron pair repulsion Because electrons repel, molecules adjust their shape so that valence electron pairs are as far apart as possible to minimize repulsion. Unshared electrons take up more room than the bonding electrons. In terms of decreasing repulsion: LP – LP > LP – BP > BP – BP

9. VSEPR Theory The process of predicting shape:
Determine what the central atom is
Draw the Lewis structure for the molecule
Determine the # of bonding pairs and lone pairs around the central atom
Refer to the chart and determine the shape of the molecule

10. VSEPR Theory
Fill in chart

11. SCH4U1 February 22nd 2011 Mr. Dvorsky
Electronegativity
SCH4U1
February 22nd 2011
Mr. Dvorsky

12. Electronegativity