Chem Stnds 8d: Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.
Forces that attract molecules to other molecules, these include:
.hydrogen bonding
.dipole-dipole attraction
.London dispersion forces
The types of bonding forces vary in their strength as measured by average bond energy.
(STRONGEST)
Covalent Bonds (400kcal)
Hydrogen Bonding(12-16kcal)
DipoledipoleRXNS(2-0.5kcal)
Lndon Forces(less than 1kcal)
(WEAKEST)
Hydrogen Bonding
Bonding b/t hydrogen and more electronegative neighboring atoms such as oxygen and nitrogen.
Polarity
A molecule, such as HF, that has a center of positive charge and a center of negative charge is said to be polar, or to have a dipole moment.
Dipole-dipole Attraction
Attraction between oppositely charged regions of neighboring molecules.
London-dispersion forces
The weakest of intermolecular forces, these forces are proportional to the mass of the molecule. These are the only forces of attraction between completely nonpolar molecules.
Links:
http://www.sciencegeek.net/Chemistry/Presentations/IntermolecularForces/
http://en.wikipedia.org/wiki/Liquid
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