Why NaCl does not conduct electricity in solid state?

AI Thread Summary
NaCl does not conduct electricity in its solid state because it lacks free-moving ions and electrons. The confusion arose from a student's response that implied NaCl might have electrons but not free-moving ones, leading to a misunderstanding. The teacher awarded no marks due to the phrasing, which could be interpreted as stating NaCl has no electrons at all. Clarifying that both ions and electrons need to be explicitly described as "free-moving" would improve the answer's clarity. Ultimately, effective communication in exams is crucial for conveying understanding.
adjacent
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Homework Statement


The title

Homework Equations


Nah

The Attempt at a Solution


It has no free moving ions or electrons

Then, my teacher saw the electrons and gave 0 marks to the question(It was on the test paper)

He said that if he didn't see electrons there, he would have given a mark.
Why? I don't understand.

If it does not have free moving ions but have free moving electrons, then it will conduct. My answer should not be wrong!
 
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I don't see problem with electrons being mentioned, quite the opposite - it looks quite OK to me.

That is, your wording can be slightly confusing. If what you mean is that NaCl crystal has no free moving ions nor free moving electrons, I would accept it. Delocalized, freely moving electrons in the conduction band are what makes solids conductive.

I will move the question to physics forum, as it is better suited there.
 
Borek said:
If what you mean is that NaCl crystal has no free moving ions nor free moving electrons, I would accept it.
Isn't that the same thing?
Can a native English speaker help me here?What do you think?
 
adjacent said:
Isn't that the same thing?
Can a native English speaker help me here?What do you think?

The way you wrote it it might be possible to interpret as you stating that NaCl doesn't have electrons which isn't true. I think your meaning is clear by context though.
 
dauto said:
The way you wrote it it might be possible to interpret as you stating that NaCl doesn't have electrons which isn't true. I think your meaning is clear by context though.

Yeah, I think he read the sentence separately:
[It has no free moving ions] [or electrons]

I think it's better to write:
[It has no free moving ions] nor [free moving electrons]. This makes more sense :smile:
 
When formally dissected, your answer states (among other things) "it has no electrons". Your adjective "free moving" is associated with ions. If you intend the adjective to also be associated with electrons then the adjective must be repeated, as Borek illustrated.

http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon2.gif Remember, an examination doesn't test a student's understanding, it tests a student's skill at convincing the examiner of his understanding.
 
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NascentOxygen said:
http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon2.gif Remember, an examination doesn't test a student's understanding, it tests a student's skill at convincing the examiner of his understanding.
I see, I will keep this in mind.
 
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