Shapes Of Molecules And Intermolecular Forces Flashcards
2 bonding clouds, 0 lone pair clouds
Linear
3 bonding clouds, 0 lone pair cloud
Trigonal planar
2 bonding clouds, 1 lone pair cloud
Bent
4 bonding clouds, 0 lone pair clouds
Tetrahedral
3 bonding clouds, 1 lone pair cloud
Pyramidal
2 bonding clouds, 2 lone pair clouds
V shaped
5 bonding clouds, 0 lone pair clouds
Trigonal bipyramidal
6 bonding clouds, 0 lone pair clouds
Octahedral
4 bonding clouds, 2 lone pair clouds
Square planar
Linear
180°
Trigonal planar
120°
Bent
Roughly 118°
Tetrahedral
109.5°
Pyramidal
Roughly 107°
V shaped
Roughly 104.5°
Trigonal bipyramidal
90°,120°,180°
Octahedral
90°
Square planar
90°
Define ionic bonding
A multi-directional electrostatic attraction between ions of opposite charge
Why do ionic compounds have high melting and boiling points
Giant ionic lattice. Electrostatic attraction between positive and negative ions are numerous and strong so lots of heat energy is required to overcome the attractions
Which ionic compounds conduct electricity and why
Solids don’t conduct because charged particles are not free to move. Molten or aqueous compounds do conduct because ions are free to move and carry the charge
What do ionic compounds dissolve in and why
Ionic compounds dissolve in water (a polar solvent) because charges in the water can attract the ions in the ionic solid causing the ions to break off and the water molecules surround the ions causing the solid to dissolve. They do not dissolve in non polar solvents because there is no attraction between the ions and the solvent molecules
Why is a giant ionic lattice formed
Oppositely charged ions that are strongly attracted in all directions
Define covalent bonding
A directional, electrostatic attraction between the 2 positive nuclei of the atoms in the bond and one or more pairs of electrons shared between them
What bonds does hydrogen form
1 single bond
What bonds do group 7 form
1 single bond
What bonds does group 6 form
2 single bonds or 1 double bond
What bonds does group 5 form
3 single bonds or 1 double and 1 single bond or 1 triple bond
What bonds does group 4 form
4 single bonds or 1 double and 2 single bonds or 2 double bonds or 1 single and 1 triple bond
How do we measure the strength of a covalent bond
Average bond enthalpy
Lone pair definition
A pair of electrons in the outer shell of an atom that is not involved in bonding
Define electronegativity
A measure of the ability of an atom in a covalent bond to attract the bonding electron density towards itself
How do you get bond polarisation
When atoms of different electronegativity are joined together
Define London forces
The attractions between temporary, flickering dipoles and induced dipoles
What does the strength of London forces depend on
The number of electrons- more electrons= stronger London forces and the symmetry/shape of molecules
Define dipole dipole attractions
The attractions between permanent dipoles in separate molecules
What is needed to form a dipole dipole attraction
Polar molecules- molecules that have a permanent dipole. To have a permanent dipole you need bond polarisation and a separation of charge
Define a hydrogen bond
An attraction between a hydrogen atom bonded to nitrogen, oxygen or fluorine in one molecule and a lone pair of electrons on an atom in an adjacent molecule
