Why does the number of electrons surrounding the central atom in a molecule decide is shape?
-As electrons all have a negative charge, each electron pair repels the other electron pairs. - The electron pairs push one another as far apart as possible.
For a molecule with 3 electron pairs around the central atom, give an example of molecule, the bond angle and the name of the shape the molecule has.
- Bond angle of 120*
- Name of shape is trigonal planar.
Give an example of molecule, the shape of the molecule, the bond angle of the molecule. For a molecule that has 4 electron pairs around the central atom.
- Bond angle 109.5*
- Name of the shape is tetrahedral.
Give an example, the name of the shape and the bond angle for a molecule with six electron apirs around the central atom.
- Bond angle 90*
- Name of the shape of the molecule is octahedral.
Why do lone pairs repel more than bonded pairs?
They repel more than bonded pairs because they are more electron dense.
What are the relative strengths of repulsion, for the most repulsive to the least.
Lone pair/lone pair > bonded pair/lone pair > bonded pair/bonded pair
Give an example, name the shape and state the bond angle of a molecule with three electron pairs around the central atom and one lone pair.
- Ammonia molecule(see diagram page 59)
- The shape is pyramidal
- Bond angle 107*
Give an example, name of shape and bond angle of a molecule with 2 lone pairs around the central atom and 2 bonded electron pairs around the central atom.
- Bond angle 104.5*
- Shape: Bent
- Water molecule
What is the repulsion from a double bond treated as?
Treated as the repulsion you would get from a single bond.
Give an example, name of shape and the bond angle of a molecule that has an atom with 2 double bonds around it.
1) CO2(go page 59 to see shape).
2) Bond angle 180*
3) Shape linear
