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Heat question

  1. Jun 17, 2011 #1
    Hii , i am new in this forum . I am in class 10th and my name is Sankalp . I have a question :

    Can you tell me why copper is better conductor of heat than iron ??
     
    Last edited by a moderator: Jun 17, 2011
  2. jcsd
  3. Jun 17, 2011 #2

    tiny-tim

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    Welcome to PF!

    Hi Sankalp! Welcome to PF! :smile:

    In an insulator, there are no free electrons, and heat is conducted only by transfer of vibrations from one molecule to another.

    In a conductor, these molecular vibrations also occur, but there is a far greater effect, of heat being conducted by movement of the electrons throughout the material (the "electron fluid").

    For the same reason, the materials which are good conductors of heat are also good conductors of electricity … for example, silver is slightly better than copper at both :approve:, and iron is a lot worse. :redface:

    See http://en.wikipedia.org/wiki/Conduction_(heat)#Overview" :wink:
     
    Last edited by a moderator: Apr 26, 2017
  4. Jun 17, 2011 #3
    I know this . The theory of electron fluid !!
    But if iron forms ions more readily than copper then iron must be better conductor of heat but its not so .

    Whyy ???
     
  5. Jun 17, 2011 #4
    The heat conduction in solids may be due to both lattice (ions) vibrations and electron conduction.
    So in general is not a simple matter to say which material is a better thermal conductor.
    For metals both electric and thermal conduction is strongly related to the free electrons and less to ions.
     
  6. Jun 17, 2011 #5
    Then what is it special in copper to make it better conductor than iron ???

    Please do add me too .
     
  7. Jun 17, 2011 #6

    tiny-tim

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    conductivity (both thermal and electrical) in metals depends on its resistance, and resistance comes mostly from the rigidity of the molecular structure (if molecules won't get out of the way of electrons, they slow down, so hard metals have higher resistance than soft metals) … see http://en.wikipedia.org/wiki/Copper#Physical" :wink:
    This is because the resistivity to electron transport in metals at room temperature mostly originates from scattering of electrons on thermal vibrations of the lattice, which are relatively weak for a soft metal.​

    the softness is caused by the weakness of the metallic bonds … in copper (and silver and gold), they are not covalent (because those elements have a complete d-shell and only one s-electron on top, see image at http://en.wikipedia.org/wiki/File:Electron_shell_029_Copper.svg" [Broken]) …
    Contrary to metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This explains the low hardness and high ductility of single crystals of copper.

    Copper, silver and gold are in group 11 of the periodic table, and they share certain attributes: they have one s-orbital electron on top of a filled d-electron shell and are characterized by high ductility and electrical conductivity. The filled d-shells in these elements do not contribute much to the interatomic interactions, which are dominated by the s-electrons through metallic bonds.​
     
    Last edited by a moderator: May 5, 2017
  8. Jun 18, 2011 #7
    ummm What are metallic bonds and how they differ from covalent or electrovalent bond ??

    Which are real s,p,d,f or k,l,m,n ?
     
    Last edited by a moderator: May 5, 2017
  9. Jun 18, 2011 #8

    tiny-tim

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    oooh, that's chemistry, i've no idea :redface:

    you'll have to look it up! :smile:
    what's k,l,m,n ? :confused:
     
  10. Jun 18, 2011 #9
    You mentioned metallic bonds in thermal conductivity :confused:
    Hey tim , you must have studied the 2n^2 rule by neils bohr .

    1st shell : K
    2nd shell : M
    and so on .


    I don't have any idea of s,p,d,f .

    Do you know any site which can teach chemistry from sheer basics to advanced level ?

    :smile:
     
    Last edited: Jun 18, 2011
  11. Jun 18, 2011 #10
    yes , you're right .
     
  12. Jun 18, 2011 #11

    tiny-tim

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    ahh, you seem to be using the special X-ray spectroscopy notation …

    for everything else, we use s p d and f

    K L M and N refer to the number of shells (the l quantum number)

    s p d and f correspond to the subscripts 1 2 3 and 4 (the n quantum number), eg L1 L2 L3

    see http://en.wikipedia.org/wiki/X-ray_notation" [Broken] for the conversion table

    (now, why couldn't you have found that? :wink:)​

    for a full explanation of s p d f, see http://en.wikipedia.org/wiki/Electron_configuration#Notation"
    see this forum's "Math & Science Learning Materials" at https://www.physicsforums.com/forumdisplay.php?f=151" :smile:
     
    Last edited by a moderator: May 5, 2017
  13. Jun 19, 2011 #12



    Are you from UK ??

    In India we study the system like this :

    The 2n^2 rule :

    For eg . There is 1st shell then no. of electrons would be given by 2n^2 :

    1. 2x1^2=2 electrons in K shell :
    2. 2x2^2=8 electrons in L shell and so on .

    Foe eg atomic number of hydrogen is 1 ie 1
    and of magnesium is 12 : ie : 2,8,2 .
     
    Last edited by a moderator: May 5, 2017
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