1. Shapes of Molecules and Bonding

2. Writing frame for explaining the shape of a molecule:
There are ______ areas of negative charge around the central ________ atom.
These repel each other to the maximum distance to form a ________ arrangement.
There are __________ bonded atoms and _________ non bonding electron pairs.
This gives an overall __________ shape.

3. Explain why ICl5 is a square based pyramid
There are six areas of negative charge around the central iodine atom.
These repel each other to the maximum distance to form an octahedral arrangement.
There are 5 bonded atoms and 1 non bonding electron pair.
This gives an overall square based pyramid shape.

4. Symmetry of shapes New shapes – which are symmetrical? Symmetrical
Asymmetrical
Trigonal bipyramidal
T-shaped
See-saw
Octahedral
Square based pyramid
Square planar
Note: even if the shape is symmetrical, if the atoms
that are bonded to the central atom are different to
each other then the dipoles will not cancel.

5. Polarity of molecules Same as last year, but new shapes to discuss.
Things to consider:
Draw the Lewis diagram and name the shape
Electronegativity of atoms (polarity of bonds)
Symmetry of molecule
Do charges overlap? Dipoles cancel?
Determine the polarity

6. Predict and discuss the polarity of SF4
SF4 has polar bonds due to F having a higher electronegativity than S.
The see-saw shape of SF4 is asymmetrical.
Therefore, the centre of positive and negative charges do not Coincide.
Therefore the dipoles do not cancel causing SF4 to be polar.