Inorganic - 6.1 - Shapes And Molecules Flashcards
(38 cards)
Linear bonding
- 180
- 2/0
Non - linear
- 104.5
- 2/2
Pyramidal
- 107
- 3/1
Trigonal planar
- 120
-3/0
Tetrahedral
- 109.5
- 4/0
Octahedral
- 90
- 6/0
Examples of shapes
- linear = CO2
- nonlinear = H2O
- trigonal planar = BF3
- pyramidal = NH3
- tetrahedral = CH4
- octahedral = SF6
How to make structure of poly atomic ions
Always start with double bonds and see where dative bonding could take place
Nitrate ion shape
Trigonal planar
Sulphate ion shape
Tetrahedral
Carbonate ion shape
Trigonal planar
Phosphate ion shape
Tetrahedral
Ammonium ion shape
Tetrahedral using DATIVE bonding
What is a dipole
The separation of charges between atoms due to differences in electronegativity causing polarity
How do London forces work
- all polar and non-polar molecules can have as the movement of electrons in the bonding chnages
- this creates a temporary/ instantaneous dipole
- due to its polarity and charge, it will induce a dipole on a neighbouring molecule
- this process continues
Why are London forces weak
Due to their temporary nature, London forces do not last long and with a large magnitude
How can London forces become stronger
The larger the number of electrons (nuclear charges), the stronger the forces induced, this will require a larger amount of energy to overcome and so results in a larger mp/bp
What are permanent dipole-dipole interactions
- only a polar molecule can have this
- when a polar molecule like HCl is around another polar molecule, it will have a force of attraction
- as it is stronger, it requires a larger amount of energy to overcome and so larger mp/bp
What are simple molecules
E.g. H2O, CO2, H2, N2, O2
Bonding in simple molecules
Simple molecules have weak intermolecular forces between molecules and strong covalent bonds between atoms
Properties of simple molecules
Due to weak intermolecular, these are easily overcome with less energy and broken however when changing state only these change. The covalent bonds are much stronger and require a lot of energy to overcome and so usually do not break.
How does non-polar dissolve in non- polar
- the interactions weaken the intermolecular forces (LF) in both and the compound dissolves, forming the LF with each other, so that the energy is conserved
Non polar with polar substances
- the interactions once again break the LF in both, however the permanent dipole-dipole interactions in the polar solvent, are too strong to be broken and so will not allow for solute to dissolve and will not form bonds with each other, making it not conserved
Polar with polar solvents
Both the LF and perm break and once again bonded tog so energy conserved however not always the case