Ch 12 - Intermolecular forces

1) draw a lewis-dot structure, 2) consider whether the molecules is polar or not, 3) determine what intermolecular forces will exist btw molecules

Steps to determining the intermolecular forces present in a certain compound:

Van der Waals forces

• weakest of the Intermolecular forces

• caused by charged asymmetry bc of the movement of electrons

• exist between all molecules

• also known as London dispersion forces

Dipole attractions

• in all polar molecules

• positive (+) region of 1 molecule will be attracted to the negative (-) region of other molecules

Hydrogen bonding

• strongest Intermolecular force

• occurs when a Hydrogen atom that is bonded to a N, O, or F atom is attracted to the unshared electron pairs of a N, O, or F atoms in an adjacent molecule

polar bonds

• Identify _____ bonds between atoms by the electron difference between the two atoms

• if an atom has a higher electronegativity than the other:

  • higher electronegativity atom —> S^-

  • lower electronegativity atom —> S^+

polar

• identify a molecule as ____ IF the polar bonds within it are distributed Asymmetrically

  • if the polar bonds within it are distributed symmetrically then they cancel each other out, making it a non-polar molecule

• _____ molecules are defined by symmetry of polar bonds