Please explain this diagram

Discussion in 'Chemistry' started by astrogirl15, Nov 17, 2008.

  1. astrogirl15 Registered Member

    Messages:
    10
    Here is a diagram of Histidine...

    http://upload.wikimedia.org/wikipedia/commons/1/18/Histidin_-_Histidine.svg


    I have researched each compound.

    NH3 is stable.
    CH is unstable The Carbon atom wants 3 more electrons in its 2nd shell.
    CO2 is stable.
    CH2 is unstable. The Carbon atom wants 2 more electrons in its 2nd shell.
    N is unstable. It needs 3 more electrons in its 2nd shell.
    NH is unstable. It needs 2 more electron in its 2nd shell.



    So how does it all fit together?
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. AlphaNumeric Fully ionized Registered Senior Member

    Messages:
    6,702
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. astrogirl15 Registered Member

    Messages:
    10
    If I got my point accross, then I see no problem.

    If your too stupid to get what im saying becasue I misspell a word, then I don't want your answer anyways.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. astrogirl15 Registered Member

    Messages:
    10
    If the hydrocarbon "CH" has 6 electrons and 1 electron.. so thats 5 in its 2nd shell... It shares one with the ammonia... which makes the ammonia unstabe? And it shares one with the carbon dioxide.. which makes it unstable... and shares one with the hydrocarbon to its left... this adds up to 8 electrons.. which makes it stable... but what happens to the ammonia "NH3", and the "CO2" which was already stable.. and now isnt....
     
  8. AlphaNumeric Fully ionized Registered Senior Member

    Messages:
    6,702
    My what?
    [/irony]
     
  9. Enmos Valued Senior Member

    Messages:
    43,184
    Your 'to stoop'-ID dude..
    I think she wants you to stoop or something..

    Please Register or Log in to view the hidden image!

     
  10. phlogistician Banned Banned

    Messages:
    10,342
    Do you want help, or do you want to fuck off?
     
  11. PreverseBeing Registered Member

    Messages:
    24
    Ok... threads are a lot more productive without insults and rejection...
    Astrogirl, I don't think your question in your first post is "clear" enough, personally, I don't know what your asking for exactly, and histidine is one of the 20 important amino acids, so you should be able to just research it anywhere.
     
  12. Trippy ALEA IACTA EST Staff Member

    Messages:
    10,890
    Actually Carbenes can be stable, and there's two different types of Carbene depending on the arrangement of the electrons in the radical. But that's a whole other story.

    Please Register or Log in to view the hidden image!



    It fits together, and Histidine is stable, because every Carbon has 4 bonds (and 8 electrons), every Nitrogen has three bonds (and 8 electrons), every Oxygen has two bonds (and 8 electrons) and every Hydrogen has one bond (and two electrons).
     
  13. astrogirl15 Registered Member

    Messages:
    10
    In other diagrams there is a +, and -.

    What do those mean, and why arent they here?
     
  14. Mr. Hamtastic whackawhackado! Registered Senior Member

    Messages:
    4,492
    Not a chemist, but I think those denote ionic polarity.
     
  15. draqon Banned Banned

    Messages:
    35,006
    the barbygirl becomes an astrogirl...
     
  16. astrogirl15 Registered Member

    Messages:
    10
    So the N has a + next to it becasue it HAD 8 electons in its covalance shell due to the 3 hydrogen, but then the carbon took one.. so now it has 7.. which means it has 9 electrons and 10 protons.. which gives it a positive charge...

    correct?
     
  17. Trippy ALEA IACTA EST Staff Member

    Messages:
    10,890
    No.

    The N has a positive charge because any atom with at least one pair of electrons can form a dative bond.

    Ordinarily when a Covalent bond is formed, it constitutes a pair of electrons, and one electron is donated by each atom in the bond.

    However, in a dative bond, one of the atoms donates both electrons to form a bond, usually it involves an atom with at least one lone pair of electrons, and a positively charged atom or molecule.

    In the case of Amino acids, the nitrogen in the amine group is capable of acting as a base (remember that ammonium hydroxide is a basic solution - this is why) and accepting a hydrogen atom from another molecule, specifically an acid that's capable of donating a proton.

    It just so happens that in this case, the amino acid is also capable of donating a proton as well, because as well as having the basic amine group, it also has the acidic carboxylate group.

    Carboxylate groups are, in essence, acidic because the oxygen is highly polar, and holds tightly onto the electron, making it easier to break the bond between the Oxygen and Hydrogen.

    The thing to remember about dative bonds is that they're indistinguishable from an 'ordinary' covalent bond. In this case the Nitrogen has a positive charge associated with it, because it has, in essence, lost an electron to the proton to form the bond (One way of thinking about it is that the positive charge of the hydrogen is 'transfered' to the Nitrogen).
     
  18. phlogistician Banned Banned

    Messages:
    10,342
    Hey trippy, why not let Astrobeatch do her own homework? Or you know, read the textbooks her school undoubtedly supplied?
     

Share This Page