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WHy are ionic bonds intramolecular forces?

  1. Dec 31, 2013 #1
    An intramolecular force is a force that holds atoms that form compounds or moleculues together. So if we have NaCl there are a large number of Na+ and Cl- so those ionic bonds hold the ions together so they are considered intramolecular.

    But say we have a mixture of molten NaCl and CaCl2 and we let them cool together. So some parts of the NaCl and CaCl2 would be mixed together - the structure would have different parts to it like Na+Cl-Ca2+Cl-Ca2+Cl-Na+ all in a random order.

    In this case how can we consider those ionic bonds intramolecular? Because now they do not hold just the ions that form the compounds but instead they hold ions that form a mixture that does not have a specific ionic structure like in pure NaCl. So what are they considered in this case?

    Thanks in advance
  2. jcsd
  3. Dec 31, 2013 #2
    When a melt is cooled, it creates (ideally) one crystal. There are no molecules as well as in NaCl crystal there are no molecules. It's "one big molecule", which means energy states are different for every single electron (that's the only Pauli exclusion principle option for a single particle). So the bonds are still intramolecular in an ideal case.

    For distribution of electron energy states the electron clouds MUST be overlapping. For ionic compounds it's quite odd (so every ionic compound has some of covalent contribution? Or might there be an overlapping without covalent contribution?). I hope somebody will explain...
  4. Jan 9, 2014 #3
    Well, this seems well coresponding, because truly every ionic crystal has covalent contribution.
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