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Topic: Couple Questions about Metallic Solids  (Read 1877 times)

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Offline galpinj

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Couple Questions about Metallic Solids
« on: October 01, 2016, 12:13:32 PM »
Hey everyone,

I have a few questions about metals.

I was working through a problem recently involving mercury, and one of the false statements was that "mercury tends to ionize". This got me thinking about the e- sea model. In metals, like aluminum or mercury, do the atoms actually "ionize"? By this I mean do they have to provide energy to overcome ionization energy? Would a atom like aluminum, which ionizes to Al3+, have to ionize three times? I bet the 1st, 2nd, and 3rd ionization energies would probably add up! Moreover, If they are ionizing, should we consider the Al3+ to be "cations" in a metallic solid? If not, what exactly is the Al3+ atom?

Finally, I was looking at how electricity moves in batteries and was trying to relate this with metals. In a battery,  electrons flow from the anode (which is electron dense) to the cathode until the charges are equalized. What about in a metal? I have never heard of a metal "running out of electrons". My thinking is that an external electron source is attached, and the electrons from this source "push" the electrons in the metal to the other end while simultaneously being replenished by the source.

Any help is much appreciated

Offline AWK

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Re: Couple Questions about Metallic Solids
« Reply #1 on: October 01, 2016, 02:58:28 PM »
Read about band theory in your thexbook or wikipedia.
AWK

Offline Enthalpy

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Re: Couple Questions about Metallic Solids
« Reply #2 on: October 01, 2016, 06:30:28 PM »
[...] In metals, like aluminum or mercury, do the atoms actually "ionize"? [...]

The electrons in a metal aren't far from the nuclei. The electrons get only shared among all nuclei. Did I already answer that same question in an other thread?

[...]In a battery,  electrons flow from the anode (which is electron dense) to the cathode until the charges are equalized. [...]

Huh. if you touch two parts of different metals with an ammeter, nothing happens. So the electrolyte does something. In addition, one electrode gets thinner or even punched through as you deplete the battery, so it's not only a matter of electrons. Have a look at Wiki maybe?

Offline galpinj

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Re: Couple Questions about Metallic Solids
« Reply #3 on: October 01, 2016, 11:03:29 PM »
Thank you guys for the reply,

@Enthalpy, so you are basically saying that, because the electrons aren't that far removed, they aren't actually being ionized. As such metallic solids shouldn't be connected with the concept of ionization energy.

Regarding the battery, I definitely agree that one electrode gets thinner and depletes. I am just curious why, if we run electrons through something like a metal wire, the electrons in the wire (the wire's "sea of electrons) and the wire itself doesn't deplete. Is this because the electrons are constantly being replenished by the source of electricity?

Appreciate the input!

Offline Enthalpy

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Re: Couple Questions about Metallic Solids
« Reply #4 on: October 03, 2016, 08:32:41 AM »
Whether academics want to call it "ionized", please check the definitions. But what's certain: forming a metal from lone atoms produces much heat, it doesn't need to first take electrons far from the nuclei, and the ionization enery helps little to understand nor evaluate this heat.

Electricity, at least in DC or at low frequencies like 50Hz or 400Hz, is a movement of charges along a closed loop. A source of electric power isn't a provider of electrons: it's a mover of charges that takes them at one electrode and injects them at the other. These charges transit in the wires.

Matter is essentially neutral because a tiny imbalance creates a huge electric field that prevents increasing the imbalance. To observe a usable imbalance, one has to provoque it
  • in a miniscule region: a transistor or diode acts on the charge equilibrium over 10nm to 300µm thickness;
  • in a material where the mobile charges are already scarce: a semiconductor, so the relative effect is important.

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