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    i understand that Sodium oxide and magnesium oxide dissolve to form OH- ions and an alkaline solution
    But with Aluminium oxide, there is a similar electronegativity, and aluminum has a polarising effect with a high nuclear charge, so the bond is not as ionic, and is too strong to be disssolved.
    Then comes silicon dioxide which is macromolecular, so it wont dissolve, because its simply too big, and in my book it says they have similar electrinegativities so no H+ and OH- ions will be formed............so wwhy on earth are there H+ ions formed for sulphur dioxide and phosphourous oxide if electronegagtivity differences decreases across period 3?? i just dont get it.
    i would be very grateful if someone can helpxxx
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    (Original post by T.r.i.n.i.t.y)
    i understand that Sodium oxide and magnesium oxide dissolve to form OH- ions and an alkaline solution
    But with Aluminium oxide, there is a similar electronegativity, and aluminum has a polarising effect with a high nuclear charge, so the bond is not as ionic, and is too strong to be disssolved.
    Then comes silicon dioxide which is macromolecular, so it wont dissolve, because its simply too big, and in my book it says they have similar electrinegativities so no H+ and OH- ions will be formed............so wwhy on earth are there H+ ions formed for sulphur dioxide and phosphourous oxide if electronegagtivity differences decreases across period 3?? i just dont get it.
    i would be very grateful if someone can helpxxx

    Aluminium oxide is actually ionic.
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    (Original post by Ralfskini)
    Aluminium oxide is actually ionic.
    i thought it was intermediate? it has some covalent bonds as well as ionic.
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    (Original post by allisandro)
    i thought it was intermediate? it has some covalent bonds as well as ionic.

    Al2O3 does indeed have intermediate bonding. The bonding has a high degree of covalency due to the polarising nature of the small highly charged Al3+ cation, which is able to distort election density from the anion back towards the internuclear axis.
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    (Original post by mongoose)
    Al2O3 does indeed have intermediate bonding. The bonding has a high degree of covalency due to the polarising nature of the small highly charged Al3+ cation, which is able to distort election density from the anion back towards the internuclear axis.
    i learnt that it has a giant covalent structure, similar to diamond.
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    (Original post by noggin)
    i learnt that it has a giant covalent structure, similar to diamond.
    Nah it's ionic with a marked degree of covalent character.
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    (Original post by vinny2256)
    Nah it's ionic with a marked degree of covalent character.
    urgh i hate chemistry. everything always contradicts itself. and if you look something up in one textbook it says something totally different to another eg. with complex ion colours i got about 10 different versions of different ion colours.
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    (Original post by noggin)
    urgh i hate chemistry. everything always contradicts itself. and if you look something up in one textbook it says something totally different to another eg. with complex ion colours i got about 10 different versions of different ion colours.
    the only suggestion that could be made for the insolubility of aluminium oxide could be the macromolecular structure...Whatelse can it be? :confused:
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    its ionic/covalent
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    (Original post by jay9386)
    its ionic/covalent
    I know that very well but the only explanation i have seen for its insolubility thus far is the fact that its lattice structure is different than that of sodium and magnesium oxide!! Do you have any suggestions?
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    no idea sowwy
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    dunno but SiO2 is also insoluble :rolleyes:
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    Basically, just say that, delta G is positive and It has stong covalent (yes there are ionic tendancies, because of the electronegativity diff, but due to the size, and +ve charge on the Al3+, it tries to 'take back' the electrons donated to oxygen! giving the bond a shared covalent nature) bonds, which are hard to break
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    (Original post by Emma18)
    Basically, just say that, delta G is positive and It has stong covalent (yes there are ionic tendancies, because of the electronegativity diff, but due to the size, and +ve charge on the Al3+, it tries to 'take back' the electrons donated to oxygen! giving the bond a shared covalent nature) bonds, which are hard to break
    eh?
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    erm...thanks everyone, im really confused!! lolz naa. thanks for your help!!
 
 
 
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