What are sigma bonds?
The head to head overlap of atomic orbitals with its electron density concentrated along the internuclear axis
What are pi bonds?
The sideways overlap of p orbitals with its electron density concentrated above and below the internuclear axis
If there is a double bond how many sigma and pi bonds does it have?
1 sigma, 1 pi
If there is a triple bond how many sigma and pi bonds does it have?
1 sigma 2 pi
Draw the structure of NO3-
Draw the structure of CO32-
Draw the structure of SO42-
Draw the structure of ozone
What are resonance structures?
Structures where there is more than one place for the multiple bond
What does formal charge tell you?
- Which lewis structure is preferred when more than one is possible
- the charge that an atom would have if all the atoms had the same electronegativity
Which formal change value is the best?
The one closest to 0
Formula charge formula
FC= VE-NE-1/2 BE
VE= valence electrons NE= non bonding electrons BE= bonding electrons
What is the formula charge for ions?
It is always the overall charge on the ion
VSPER theory
- predicts the shape of the molecules ( MDG)
- electron pairs repel each other as far apart as possible
- EDG = the number of electron domains
5 electron domains ( 5 bonding domains, 0 lone)
- trigonal bipyramidal
- 90 degrees / 120
5 electron domains ( 4 bonding domains , 1 lone)
- see saw
- <90/<120
5 electron domains ( 3 bonding domains, 2 lone)
- T shaped
- < 90
5 electron domains ( 2 bonding domains , 3 lone domains )
- linear
- 180 degrees
6 electron domains ( 6 bonding domains , 0 lone)
- octahedral
- 90 degrees
6 electron domains ( 5 bonding domains, 1 lone domain)
- square pyramidal
- < 90
6 electron domains ( 4 bonding, 2 lone)
- square plannar
- 90 degrees
Equations for destruction of ozone by NO
NO. + O3 = NO2. + O2
NO2. + O3 = NO. + 2O2
Equations for the destruction of ozone for CFCs
CCl2F2 – CClF2. + Cl. ( by U.V.)
Cl. + O3 = ClO. + Cl.
ClO. + O. = Cl. + O2
Hybridisation
