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In terms of electronegativity, from what I understand electronegativity increases going across the period, so surely this should mean that zinc less readily loses its outer shell electrons than copper? Zinc has a greater nuclear charge but the outer shell electrons are in the same shell, so should the outer shell electrons in zinc not experience a stronger attraction to the nucleus? I have a feeling that this has something to do with which sub shells the electrons are removed from in copper and zinc...

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  • $\begingroup$ By reactivity, do you mean standard reduction potential? $\endgroup$ – Brinn Belyea Feb 16 '15 at 16:44
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    $\begingroup$ I am learning about half cells, so it is in this context. Zinc loses its valence electrons more readily than copper, and also when zinc is placed into copper sulfate solution it will displace the copper, so is more reactive... $\endgroup$ – Meep Feb 16 '15 at 16:46
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    $\begingroup$ For an extremely thorough discussion of the findamentals, see this paper: K. Schmidt-Rohr, "How Batteries Store and Release Energy: Explaining Basic Electrochemistry", J. Chem. Ed., 95(10 (2018) 1801-1810. The Zn and Cu Daniell cell is addressed at great length (way too long for an answer here) and the metal cohesive energy is the source of more than 75% of the energy in the Daniell cell (p. 1805.). $\endgroup$ – Ed V Jul 24 at 15:17
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You have to think about the whole process. When a metal loses electrons to make a metal ion the following happens:

  1. The metallic bonds holding the metal atoms together are broken.
  2. The metal atom loses the electrons.
  3. The resulting metal ion is hydrated.

In your analysis you are only focusing on step 2. The enthalpy and entropy of the entire process factor into the reduction potential.

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  • $\begingroup$ So why do we need to ionize two electrons? Do we need two electrons from sodium or silver? Is two electrons enough for aluminum or chromium? $\endgroup$ – Oscar Lanzi Dec 7 '17 at 17:20
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    $\begingroup$ I edited the answer to make it more general for any number pf electrons lost. $\endgroup$ – Brinn Belyea Dec 8 '17 at 0:22
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Zinc has last sub orbital as $\mathrm{4s^2}$ which it gives willingly to become electronically stable. Also, zinc's pull on its last electronic shells is much less and is hence more willing to combine. Copper has a last sub-orbital as $\mathrm{4s^1}$ which decreases its capacity to form bonds like zinc. Ideally, copper should form more bonds but due to lack of electrons in the last shell, it cannot form many bonds.

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Zinc is more reactive than copper not because the last sub orbital of zinc is $\ce{4s^2}$ while of copper is $\ce{4s^1}$ if it is than according to this magnesium should be more reactive than sodium as the last sub orbital of magnesium is $\ce{3s^2}$ while of sodium is $\ce{3s^1}$ so this is not the case why zinc is more reactive than copper, ok remember it.

Now then question arises what is the reason of being zinc more reactive than copper??

So the answer is zinc is more reactive than copper because zinc able to loose its outer electron more readily than copper and this phenomena occurs because the copper metal is able to delocalized its outer electron more readily than zinc so the metallic bond of copper is stronger than zinc so for having reaction it becomes necessary to break this bond first and breaking the metallic bond of copper require more energy than that of zinc and hence as the metallic bond of zinc breaks zinc reacts.This is the reason why zinc is more reactive than copper

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I think that copper would me more reactive than zinc because copper will more act as a ion rather than acting as a metal.

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protected by Community Jul 23 at 16:24

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