omario4 - 25-8-2008 at 17:02
for negative polyatomic ions, is their overall charge due to the nonmetals in the compound? like with hydroxide or phosphates. if so why don't we just
say its the oxygen that is negative instead of the whole compound?
OH- is negative because oxygen took an extra electron from another atom right?
Klute - 25-8-2008 at 17:18
Yes, basicly. But depending on the molecule, the negative charge can be delocated according to several resonance structures. It would be meaningless
to say only one atom is negatively charged, as it is linked to all the other atoms of the molecule, which are somewhat affected by this charge
(inductive effect for example)
ScienceSquirrel - 25-8-2008 at 17:26
Only very simple anions eg F- in some compounds eg KF have a simple structure in which the anion accepts the whole of the negative charge.
Most oxy anions eg chlorate, nitrate or sulphate have a high degree of delocalisation of charge and in some cases hydration that stabilises the solid
salt.
omario4 - 25-8-2008 at 18:02
Ah ok, I think I understand. Thank you very much guys.