The failure of the free electron theory of metals

In summary, the free electron model of metals failed because it was unable to account for electron-electron interactions.
  • #1
ziadett
8
0
I was woundering?

why did the free electron theory of metals fail (the free electron model)?
 
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  • #2
why did the free electron theory of metals fail "the free electron of model"
my effort:
Because it was unable to answer why the mean free path of electrons reaches 20nm in a good conducting metal "like silver" in room tempereture.
 
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  • #3
any answers
 
  • #4
Who said it failed?
 
  • #5
nbo10 said:
Who said it failed?

Ashcroft and Mermin did in the whole of Chapter 3 of their book "Solid State Physics".

Zz.
 
  • #6
ziadett said:
why did the free electron theory of metals fail (the free electron model)?
The free electron model (as put forth by Drude, and modified by Sommerfeld and others) "failed" because for the most part, electrons aren't completely free. They interact with (i) the lattice, (ii) each other, and (iii) impurities. Drude incorporated (i) into his model in the form of a hard-sphere interaction, but completely neglected the other interactions. Sommerfeld made some corrections to this purely classical model, by ensuring that the electron gas obey Fermi statistics. This fixed some problems (like the overestimates of the electronic heat capacity), but still didn't cover for the missing interactions in the model.

The free electron model was understood to be an approximation, when it was proposed by Drude. The initial surprise was that it was far more successful than expected (eg: the Wiedemann-Franz Law), particularly in the case of the alkali and alkaline Earth elements.

Due to its limitations, the free electron model was unable to account for things like magnetoresistance, thermal dependence of conductivity, optical properties and the host of many body phenomena that result from electron-electron interactions being of importance.
 
  • #7
Aren't the "free-electron theory" and the "free-electron model" the same thing?

You might try looking up the "nearly-free- electron model."
 
  • #8
Look up chapter three in Ashcroft&Mermin, it just happens to be named "Failures of the Free Electron Model" and probably contains more than enough information for you.
 
  • #10
Thread merged.

ziadett : I strongly suggest you re-read the PF Guidelines that you have agreed to. There is a an explicit instruction that multiple posting is not allowed.

Zz.
 
  • #11
sorry man no more multiple posting from me any more
 

1. What is the free electron theory of metals?

The free electron theory of metals is a model used to explain the behavior of electrons in metallic substances. It proposes that the valence electrons in a metal are not bound to a specific atom, but rather move freely throughout the entire metal lattice.

2. What are some limitations of the free electron theory of metals?

One of the main limitations of the free electron theory is that it fails to account for the observed resistivity of metals at low temperatures. This is known as the "resistivity plateau" and is not predicted by the theory. Additionally, the free electron theory does not explain the existence of energy bands in metals, which is a fundamental concept in modern solid state physics.

3. What alternative theories have been proposed to replace the free electron theory of metals?

Several alternative theories have been proposed to explain the behavior of electrons in metals, including the band theory of solids, the Fermi liquid theory, and the nearly-free electron model. These theories take into account the concept of energy bands and provide a more accurate description of electron behavior in metals.

4. How does the failure of the free electron theory impact our understanding of metallic substances?

The failure of the free electron theory has led to the development of more sophisticated theories that better explain the properties of metals. It has also allowed for a deeper understanding of the electronic structure of metals and how it contributes to their physical properties. Furthermore, the failure of the free electron theory has highlighted the need for continued research and development in the field of solid state physics.

5. Are there any practical implications of the failure of the free electron theory?

Yes, the failure of the free electron theory has practical implications in the development of new materials and technologies. By understanding the limitations of the theory, scientists are able to design and engineer materials with specific electronic properties, leading to advancements in fields such as electronics, energy storage, and materials science.

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