Intermolecular Forces Prince Steven Courtney David Shavonte London Dispersion Forces Attraction from when the electrons in 2 adjacent atoms occupy areas that form temporary dipoles Strength: Weak strength unless around a lot of surface area Effect: Condenses liquids to solid form in cold temperatures. Ex: Liquid Methane Ion-Dipole Forces Results from the electrostatic attraction between an ion and a neutral molecule that has a dipole Strength: Weak compared to intramolecular forces Effect: Cation attracts the partially negative end and Anion attracts the partially positive end Ex: Na+ with Cl- Hydrogen Bonding Electromagnetic attractive interaction of a polar hydrogen atom in a molecule and an electronegative atom Strength: Relatively strong but varies. 5x as strong as dipole Effect: Causes water to become polar and “universal solvent” Ex: Water, Alcohol, DNA Dipole-Dipole Forces Attractive forces between the positive end of one polar molecule and the negative end of another Strength: Weaker than ionic and covalent bonding Effect: Electron density builds up Ex: HCl http://www.chem.purdue.edu/gchelp/liquids/hbond.html http://www.chem.purdue.edu/gchelp/liquids/dipdip.html http://www.chem.purdue.edu/gchelp/liquids/iondip.html http://www.chem.purdue.edu/gchelp/liquids/disperse.html