VanderWaalsForcesfor2B - Br Br Br Br ! ! ! ! Temporary...

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Jim Hollister LSC/UCDavis Van der Waals Forces I. Ionic Interactions: strongest attractions II. Van der Waals Forces: intermolecular attractions A. Permanent dipole-dipole interactions: H C O H ! ! H C O H ! ! Permanent dipole-dipole interaction 1. H-Bonding: Special case of permanent dipole-dipole interactions: when H is bonded to the highly electronegative elements N, O, or F, H-bonding can occur. H 3 C H O C H 3 H O Hydrogen bonding ( H-bonding raises the boiling point higher than one would expect based on the molecular mass alone. See London Forces below.) B. London Forces: Instantaneous (temporary) dipole-dipole interactions.
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Unformatted text preview: Br Br Br Br ! ! ! ! Temporary attraction between molecules caused by a random electron excess at one Br which makes it a partial negative bromine. It causes one of the adjacent molecule's bromines to be partially positive because of electron repulsions. Boiling pt. London Forces number of electrons molecular mass (or Melting pt. or H of vaporization) means proportional to The higher the molecular mass, the higher the number of electrons in a molecule, the higher the London Forces, the higher the boiling pt. (or Melting pt. or H of vaporization)...
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