ie-Chemistry P6

in development


While ionic bonds are among the strongest holding molecules together (as a result, they require among the highest temperatures to melt), they have two Achilles heels:  they have electrically positive charged ions and electrically negative charged ions.  Molecules capable of far weaker polar forces can team up on each kind of ion and pluck them from their crystal lattice.  The result is a solution with an entourage of polar molecules surrounding each ion so freed from its ionic solid.  For example, polar molecules such as water, HOH, rotate so that positive ions are surrounded by the negative sides of the dipoles (in the case of water, the Oxygen hoards shared electrons so is a bit negative), and negative ions are surrounded by the positive side of the polar molecules (in water, the Hydrogen mostly lacking their shared electrons, is left partially positively charged).  As a result, nearly all solids held together by the very strong ionic forces can still be dissolved to form solutions in polar solvents such as water.  (These two facts can be turned around to form easy tests to identify substances with ionic bonds:  If a substance dissolves in water yet requires high temperature to melt, it is very likely an ionic substance!)





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created 24 August 2009
revised 2009
by D Trapp
Mac made