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8.4 Attractive Forces part 2 – cont. Weaker Forces of Attraction.
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Weaker Forces of Attraction • Weaker forces are temporary attractions that exist between neighboring particles due to temporary or permanent partial charges (+ or -) on the particles. The attractions are usually indicated in diagrams using dashed lines. ------- • Attractions also vary in strength, depending upon the identity of the substances involved, and this strength is indicated by how much energy is required to break the bond.
Weaker Forces of Attraction • Since an ion is involved in the ion-dipole interaction, these attractive forces tend to be stronger. It can take from 40-600 kJ/mol to break these bonds.
Weaker Forces of Attraction • In dipole-dipole interactions, these attractive forces are significantly weaker due to only partial charges being involved.
Weaker Forces of Attraction • They require only 5-25 kJ/mol to break these attractions between neighboring particles. • The amount depends upon the size of the partial charges.
Weaker Forces of Attraction • Hydrogen bonding is another one of the weaker forces of attraction that can exist between particles. It takes from 10-40 kJ/mol to break these bonds. Hydrogen Bonding.flv
Weaker Forces of Attraction • One of the most common substances that forms hydrogen bonds is water: molecular_dance_of_water's_hydrogen_bonds.flv
Weaker Forces of Attraction • The weakest force of attraction that can occur between particles in a substance involves induced dipoles.
Weaker Forces of Attraction • Induced dipoles can exist in atomic substances (like xenon) in addition to molecules. Larger atoms or molecules can have larger induced dipoles due to the presence of more electrons.
Weaker Forces of Attraction • The forces attracting induced dipoles are referred to as London dispersion forces, and can require between 0.05-40 kJ/mol to break.
Weaker Forces of Attraction • London dispersion forces are weaker forces because induced dipoles are temporary; they don’t exist for long, but may reform quickly.
References: • http://www.chem.purdue.edu/gchelp/liquids/character.html • http://www.chem.wisc.edu/~newtrad/CurrRef/BDGTopic/lab/Crystlab2.GIF • http://lgfl.skoool.co.uk/uploadedImages/coord11.2_covalentbonding2_v2.gif • http://www.dur.ac.uk/p.m.johnson/electric_circuits/images/dia_atom_cores.gif • http://www.chemistry.wustl.edu/~courses/genchem/Tutorials/Water/images/nacl.jpg • http://web.arc.losrios.edu/~borougt/DiamondStructure.jpg • http://www.oocities.org/rjwarren_stm/PolarityOHbond.jpg • http://www4.nau.edu/meteorite/Meteorite/Images/HydrogenBond.jpg • http://cost.georgiasouthern.edu/chemistry/general/molecule/polar.htm • http://virtual.yosemite.cc.ca.us/webbg/chem101/ch11lecture/intermolecforces.htm • http://www.grandinetti.org/resources/Teaching/Chem121/Lectures/BondPolarity/ColvanttoIonic.gif • http://www.drkstreet.com/resources/metallic-bonding-animation.swf • http://www.chem.ufl.edu/~itl/2045/matter/FG11_002.GIF • http://mysite.verizon.net/kdrews47/interactions/ldf.gif • http://www.colorado.edu/physics/2000/applets/h2ob.html • http://antoine.frostburg.edu/chem/senese/101/liquids/faq/h-bonding-vs-london-forces.shtml • http://cost.georgiasouthern.edu/chemistry/general/molecule/forces.htm • http://www.bbc.co.uk/scotland/learning/bitesize/higher/chemistry/images/bonding_fig11.gif • http://www.northland.cc.mn.us/biology/Biology1111/animations/hydrogenbonds.html • http://www.chem.purdue.edu/gchelp/liquids/ioninddp.gif • http://chemwiki.ucdavis.edu/@api/deki/files/3831/=160inducedipole.gif
References - Videos: • http://www.youtube.com/watch?v=QqjcCvzWwww • http://www.youtube.com/watch?v=LKAjTE7B2x0&NR=1 • http://www.youtube.com/watch?v=LGwyBeuVjhV • http://www.youtube.com/watch?v=cThvGD-o_90