UNIT 3.1 INTERMOLECULAR FORCES
Chemistry is the study of matter and interactions. Chemistry overlaps with many other sciences.
Below is the contents for this sub unit.
INTERMOLECULAR FORCES REVIEW
HYDROGEN BONDING
Hydrogen bonding is the strongest of the intermolecular forces. It is not actually a bond but a strong attractive force between a positive H atom of a polar bond and nitrogen, oxygen, or fluorine atom which produce a negative atom in a bond due to electronegativity. Be sure to review the presentation from Chem 1.
The N, O, or F can be on the same molecule or a different molecule.
DIPOLE-DIPOLE AND ION-DIPOLE FORCES
A dipole is when one side of the molecule has a slight + and another has a negative. This can lead to dipole-dipole attraction between molecules.
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Ions have a charge by nature and can be attracted to a dipole of the opposite charge. This is called an ion-dipole intermolecular force. This force tends to be stronger than a dipole-dipole.
LONDON DISPERSION FORCE
When a molecule or atom is non-polar, then it can still have a temporary polar force called London Dispersion. This happens when the electrons are unbalanced on the atom or molecule but as they move, this is temporary. However a polar molecule or ion can induce this in non-polar substances.
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It is more likely to happen (and be stronger) when the molecule is larger and has more electrons. This is the most common force in large molecules.