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    Why the 1st ionisation energy of copper is higher than that of chromium?
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    (Original post by shafia13)
    Why the 1st ionisation energy of copper is higher than that of chromium?
    What are the similarities and differences of Cu and Cr?
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    (Original post by shafia13)
    Why the 1st ionisation energy of copper is higher than that of chromium?
    As you go across the period, the nuclear charge increases (due to more protons in the nucleus) the atomic radius decreases (as the increases nuclear charge 'pulls' the electrons slightly closer to the nucleus, similar electron shielding. All of these factors mean that the electrostatic force of attraction between the nucleus and other electron is higher in Cu than in Cr, so more energy is need to overcome the electrostatic force, so the 1st ionisation energy is higher for Cu than Cr.
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    (Original post by B_9710)
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    Giving full answers doesn't really help the person.
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    (Original post by alow)
    What are the similarities and differences of Cu and Cr?
    Similarities:Both the elements have 1 electron in 4s sub-shell.
    Differences:The 3d sub-shell of chromium is half-filled whereas the 3d sub-shell of copper is full-filled.
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    (Original post by shafia13)
    Similarities:Both the elements have 1 electron in 4s sub-shell.
    Differences:The 3d sub-shell of chromium is half-filled whereas the 3d sub-shell of copper is full-filled.
    You need to think about the nuclear charge, and what effect that will have as well.
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    (Original post by alow)
    Giving full answers doesn't really help the person.
    Apologies.
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    (Original post by alow)
    You need to think about the nuclear charge, and what effect that will have as well.
    I am still not clear.I mean,both the elements have one electron in their outermost shell(4s orbital),so wouldn`t they require the same amount of energy to remove the electron?I would`ve thought about nuclear charge but in edexcel student book(transition metals) they only discussed about the electronic configuration of the transition metals when explaining ionisation energies.
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    (Original post by shafia13)
    I am still not clear.I mean,both the elements have one electron in their outermost shell(4s orbital),so wouldn`t they require the same amount of energy to remove the electron?I would`ve thought about nuclear charge but in edexcel student book(transition metals) they only discussed about the electronic configuration of the transition metals when explaining ionisation energies.
    Electronic configuration is important, but Cu and Cr are special cases due to their electron configurations having a half filled (Cr) or fully filled (Cu) set of d orbitals, which is energetically favorable. This means the 4s electron will be the first to be liberated in both cases.

    The increased charge in the nucleus of Cu means there is a greater electrostatic force attracting the electrons to the nucleus. What this means is you get more electron density closer to the nucleus (i.e. the electrons are held closer).

    Considering Coulomb's law, what would this mean for removal of an electron?
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    (Original post by alow)
    Electronic configuration is important, but Cu and Cr are special cases due to their electron configurations having a half filled (Cr) or fully filled (Cu) set of d orbitals, which is energetically favorable. This means the 4s electron will be the first to be liberated in both cases.

    The increased charge in the nucleus of Cu means there is a greater electrostatic force attracting the electrons to the nucleus. What this means is you get more electron density closer to the nucleus (i.e. the electrons are held closer).

    Considering Coulomb's law, what would this mean for removal of an electron?
    The electrostatic force between the nucleus and the outermost electron of Cu will be higher than that of Cr and so more energy will be required to remove the electron. But there is still one question bothering meince the 3d sub-shell of Cu carries 10 electrons, there would be greater repulsion between 3d electrons and 4s electron and so 4s electron of Cu would be repelled away from nucleus to a greater distance.So shouldn`t the ionisation energy for Cu be lower?
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    (Original post by shafia13)
    The electrostatic force between the nucleus and the outermost electron of Cu will be higher than that of Cr and so more energy will be required to remove the electron. But there is still one question bothering meince the 3d sub-shell of Cu carries 10 electrons, there would be greater repulsion between 3d electrons and 4s electron and so 4s electron of Cu would be repelled away from nucleus to a greater distance.So shouldn`t the ionisation energy for Cu be lower?
    The 3d electrons orbitals are more diffuse than 4s. This means that they are not very effective at shielding 4s electrons. The electrostatic attraction with the nucleus is more important.
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    (Original post by alow)
    The 3d electrons orbitals are more diffuse than 4s. This means that they are not very effective at shielding 4s electrons. The electrostatic attraction with the nucleus is more important.
    Got it.Thank you!
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    (Original post by shafia13)
    Got it.Thank you!
    No problem
 
 
 

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