polarisation and intermolecular forces
- Created by: Margaret Hobart
- Created on: 02-05-21 11:38
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- polarisation and intermolecular forces
- electronegativity
- electronegativity depends on...
- atomic radius
- nuclear charge
- shielding
- electronegativity depends on...
- permanent dipole-dipole forces
- polar bond
- stronger than VDWs
- weak electrostatic forces of attraction
- dipole is the difference in charge between two atoms caused by a shift in e- density in the bond
- covalent bond between two atoms of the same element are non-polar
- atoms with similar electronegativities are essentially non-polar
- not all molecules that have polar bonds are polar
- if polar bonds are symmetrical then the charges cancel out
- intermolecular forces are weaker than covalent, ionic and metallic bonds
- they affect the physical properties of a compound
- induced dipole-dipole (vander waals) forces
- e- in charge clouds are always moving
- dipoles are constantly being created and destroyed
- weakest
- straight molecules can lie closer together than beached ones and so have stronger VDWs
- higher boiling point
- larger molecules have larger e- clouds so stronger VDWs
- higher boiling point
- larger molecules have larger e- clouds so stronger VDWs
- evidence
- halogens are non-polar and diatomic
- as their Mr increases so does their bp/mp
- halogens are non-polar and diatomic
- e- in charge clouds are always moving
- hydrogen bonding
- strongest
- occur between H and either F, O or N
- FON=very electrogenagtive
- ice floats because as the water cools to form ice, the molecules make more H bonds and arrange themselves in a lattice
- H2O molecules are further apart in ice and so ice is less dense
- electronegativity
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