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    1)why d-block metal do not give hydrogen gas when react with acid?
    2) higher oxidation states are not observed from left to right across the d-block elements, why?
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    What have you tried so far?
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    for 2. think about what is required to go to a higher oxidation state, (successive ionisation energies), and then how ionisation energies vary across the period
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    (Original post by cupsoftea)
    for 2. think about what is required to go to a higher oxidation state, (successive ionisation energies), and then how ionisation energies vary across the period
    d block elements have similar ionisation energy?
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    (Original post by tan71500)
    d block elements have similar ionisation energy?
    Think about periodic trends. The d block elements do not have the same IE. Moving across the group, lets take the 1st row transition metals, from Ti --> Zn , you are increasing the effective nuclear charge (Zeff). You are filling up the 3d orbital, d1 --> d10 electrons, as you go across the series.

    So as an example, Ni d8 has greater Zeff than Ti d2, meaning its valence electrons experiences greater attraction to the nucleus and therefore is bound more tightly by the nucleus and harder to be ionised, hence a higher IE.

    Increase in Zeff across the series = increase in IE
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    (Original post by cupsoftea)
    Think about periodic trends. The d block elements do not have the same IE. Moving across the group, lets take the 1st row transition metals, from Ti --> Zn , you are increasing the effective nuclear charge (Zeff). You are filling up the 3d orbital, d1 --> d10 electrons, as you go across the series.

    So as an example, Ni d8 has greater Zeff than Ti d2, meaning its valence electrons experiences greater attraction to the nucleus and therefore is bound more tightly by the nucleus and harder to be ionised, hence a higher IE.

    Increase in Zeff across the series = increase in IE
    oh i get it, because of higher IE, electrons are harder to remove, so the oxidation state do not increase across the period?
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    (Original post by tan71500)
    oh i get it, because of higher IE, electrons are harder to remove, so the oxidation state do not increase across the period?
    Are you a chemistry undergraduate?

    If so I imagine you need more detail, ie showing the pattern of oxidation states that are stable across the series, it is not just a straight decrease across the period, it increases first, peaking at Mn, where you get some Mn7+ species (these are highly oxidising), then decreases again, so you need to look into that - probably explained on your lectures
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    (Original post by cupsoftea)
    Are you a chemistry undergraduate?

    If so I imagine you need more detail, ie showing the pattern of oxidation states that are stable across the series, it is not just a straight decrease across the period, it increases first, peaking at Mn, where you get some Mn7+ species (these are highly oxidising), then decreases again, so you need to look into that - probably explained on your lectures
    is it because the trend decreases as the tendency for d electrons to participate in bonding decreases?
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    (Original post by alow)
    What have you tried so far?
    is it because the metals are coated with a layer of metal oxide which prevent the reaction?
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    (Original post by tan71500)
    is it because the trend decreases as the tendency for d electrons to participate in bonding decreases?
    If you are a chemistry undergrad this is quite a basic trend that underlies a lot of transition metal chemistry, and relies on knowing Zeff and electron configs, and IE's. I suggest googling 'transition metal oxidation states' and looking at a website like chemwiki, or finding a good text book on it. You need to think more specific than what you're saying, and think purely in terms of electron configuations of each metal and why each metal does or doesn't form stable high oxidation states, related to IE in particular.
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    (Original post by tan71500)
    is it because the metals are coated with a layer of metal oxide which prevent the reaction?
    Why do you think d-block metals don't produce H2 when reacted with acids?
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    (Original post by alow)
    Why do you think d-block metals don't produce H2 when reacted with acids?
    they are lower than hydrogen in the ECS?
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    (Original post by tan71500)
    they are lower than hydrogen in the ECS?
    That's for H+ at 1M. d-block metals do produce hydrogen when reacted with more conc. acids... http://www.rsc.org/learn-chemistry/r...id=CMP00005227
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    For 2) I'd suggest reading up on ligand field theory and ligand field stabilisation energies to explain this trend.
 
 
 
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