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    why are Cr and Zn hydroxides amphoteric ? as opposed to period 3 transition metals ?

    ie [cr(h20)3(oh)3]

    thank you
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    Hey, check out this link:
    https://www.boundless.com/chemistry/...ic-hydroxides/
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    (Original post by shumen9523)
    Hey, check out this link:
    https://www.boundless.com/chemistry/...ic-hydroxides/
    thank you but do you know why cr and zn specifically hve amphoteric hydroxides ?
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    (Original post by jojo1995)
    thank you but do you know why cr and zn specifically hve amphoteric hydroxides ?
    Unfortunately, I don't :/
    I'll ask some of my friends and if I find find out something new I'll post it on this thread.
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    (Original post by shumen9523)
    Unfortunately, I don't :/
    I'll ask some of my friends and if I find find out something new I'll post it on this thread.
    Aww thank you, that would be great - thank yôu for all your help
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    (Original post by jojo1995)
    Aww thank you, that would be great - thank yôu for all your help
    Hello , these hydroxides are considered amphoteric because they can react/ dissolve in both acids and bases.

    Amphoteric is something that have got acidic and basic properties - for example : Amino acids are considered amophoteric since the COOH (aka carboxylic acid group) can donate a proton and hence acting as a Bronsted Lowry acid but the NH3 (aka the amine group) can accept a proton and hence it is acting as a BL base.

    If you need equations , I can give them to you for the chromium oxide dissolving in both acid and base.
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    (Original post by laurawoods)
    Hello , these hydroxides are considered amphoteric because they can react/ dissolve in both acids and bases.

    Amphoteric is something that have got acidic and basic properties - for example : Amino acids are considered amophoteric since the COOH (aka carboxylic acid group) can donate a proton and hence acting as a Bronsted Lowry acid but the NH3 (aka the amine group) can accept a proton and hence it is acting as a BL base.

    If you need equations , I can give them to you for the chromium oxide dissolving in both acid and base.
    Thank you do you know in terms of electonic configuration what makes cr and zn able to form amphoteric hydroxides - since they are the other transition metals in the first row - period 3/4 don't form amphoteric hydroxides ?
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    (Original post by jojo1995)
    Thank you do you know in terms of electonic configuration what makes cr and zn able to form amphoteric hydroxides - since they are the other transition metals in the first row - period 3/4 don't form amphoteric hydroxides ?
    Cr and Zn certainly have unique or initially surprising electron configurations (perhaps you already know this), with an incomplete 4s shell in order to reach a half-complete (5 electrons) or complete (10 electrons) 3d shell.

    As far as I know, though, what really makes them amphoteric is, being transition metals, they have d-orbitals available for bonding and this means they can take on a lot more substituents. When the substituents are binding onto transition metals in solution, they are called ligands and the ion is a complex ion. Because transition metals such as Cr and Zn undergo this process of complex formation, taking on the ligands, they can both dissociate and associate ligands, and if the ligand were OH- (or H+) they would come to be known as amphoteric.

    Hope this helps
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    (Original post by Big-Daddy)
    Cr and Zn certainly have unique or initially surprising electron configurations (perhaps you already know this), with an incomplete 4s shell in order to reach a half-complete (5 electrons) or complete (10 electrons) 3d shell.

    As far as I know, though, what really makes them amphoteric is, being transition metals, they have d-orbitals available for bonding and this means they can take on a lot more substituents. When the substituents are binding onto transition metals in solution, they are called ligands and the ion is a complex ion. Because transition metals such as Cr and Zn undergo this process of complex formation, taking on the ligands, they can both dissociate and associate ligands, and if the ligand were OH- (or H+) they would come to be known as amphoteric.

    Hope this helps
    Thank you so much, this is brilliant !!
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    (Original post by jojo1995)
    Thank you so much, this is brilliant !!
    Oops sorry, I have to amend that!

    I wasn't looking at the periodic table when I did it so I got Zn mixed up with Cu. Zn has both 10 electrons in the 3d-shell and 2 in the 4s-shell; it has the configuration you expect. Cu has 3d10 4s1 which you wouldn't expect.

    Anyway, that doesn't change the ligand binding explanation which is the true answer for your question, but I couldn't let such a big mistake go uncorrected
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    (Original post by Big-Daddy)
    Oops sorry, I have to amend that!

    I wasn't looking at the periodic table when I did it so I got Zn mixed up with Cu. Zn has both 10 electrons in the 3d-shell and 2 in the 4s-shell; it has the configuration you expect. Cu has 3d10 4s1 which you wouldn't expect.

    Anyway, that doesn't change the ligand binding explanation which is the true answer for your question, but I couldn't let such a big mistake go uncorrected

    That's fine, thank you for telling me !!
 
 
 
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