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Thread: chemical bonding

  1. #1 chemical bonding 
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    'i can understand the electron deal , the ionic and covalant!

    but the weak van der vhal and pi bonds and the hydrogen .. mess my head up...

    any one know any good net notes? or the likes :?


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  3. #2  
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    H+
    ....O-
    H+

    The above is a model of a H20 model. Now, instead of the two H models being properly distributed, they are distributed on one side.

    This means, that one side of the molecule is charged positively, the other side negatively. Of course, the pull of these negatives and positives is many times weaker than a full ionic pull.

    Simplified,

    - () +

    You have a plus and minus side to a molecule. This is especially true for soap, which has a + and a - side.

    The + and - is not as powerful as other bonds, but is still pretty powerful, and makes molecules stick together.

    Mr U


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  4. #3  
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    good, good,

    i can sorta understand, but not as much as i should!
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  5. #4  
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    covalent are between non-metals, ionic between metals and non-metals, metallic between metals. Metals give an electron, and thus have a positive charge, non-metals take the electron and have a negative charge. So, the males are metals (since they are in possesion of electons/money and must give them to their partners) while non-metals are women (who simply take the electrons that their partners so graciously donate). Covalent is between 2 women, you can remember this easier because when you put a dollar between two women, they both covet it. Covet = covalent. It helps.
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  6. #5  
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    Quote Originally Posted by hotsexyangelprincess
    covalent are between non-metals, ionic between metals and non-metals, metallic between metals. Metals give an electron, and thus have a positive charge, non-metals take the electron and have a negative charge. So, the males are metals (since they are in possesion of electons/money and must give them to their partners) while non-metals are women (who simply take the electrons that their partners so graciously donate). Covalent is between 2 women, you can remember this easier because when you put a dollar between two women, they both covet it. Covet = covalent. It helps.
    never looked at it like that!


    Your name.. it is a mouth ful to pronunce... (but as far as im concerned ,.. hot=sexy!!!)
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  7. #6  
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    Quote Originally Posted by hotsexyangelprincess
    covalent are between non-metals, ionic between metals and non-metals, metallic between metals. Metals give an electron, and thus have a positive charge, non-metals take the electron and have a negative charge.
    There can also be covalent bonds between a metal and a non-metal, or between two metal atoms. Also, there are many compounds in which non-metals "donate" electrons to a metal.
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  8. #7 Keep in mind... 
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    there is no point at which ionic becomes covalent exactlly, the important thing is to recognise that the larger the difference in electronegativity the more inonic the bond becomes. The terms covalent and ionic overlap.

    Van der waal bonding simply refers to all intermolecular bonds that exist due to dipolar interactions, they are the weakest of all forms of bonds. A dipole is a molecule with distinct positive and negative regions. They exist in a handful of forms but only permanently amongst few covalent molecules. The strongest example of this is Hydrogen bonding.

    Hydrogen bonding is one example of a van der waal bond, where a bond is formed between hydrogen and either oxygen, flourine or nitrogen which all attract the electron belonging to the hydrogen with a great deal of force. The hydrogen is then effectively souly a proton and attributes a very high density of positive charge to it's end of the molecule. In water water for example the H2O dipoles are permenent and line up such that positive meets negative, creating strong intermolecular forces. This is the reason water is a liquid under normal conditions, when given its molecular size it should be a gas.

    After van der waal bonds, ionic bonds are second weakest forms, these gradually gain stregnth accros the periodic groups until we call them covalent. Covalent bonds are themselves categorized by strength. Sigma bonds are the strongest and occur between low orbiting electrons such that the participating atoms can remain in close proximity. Pi bonds are weaker for the reason that they involve electrons from outer shells.

    Notes:
    We have this view of orbitals being discrete, but for example in metals we have a merging effect in which electrons can drift without being found in any specific orbit. This proccess known as hybridisation also occurs (and i dont fully understand this) to allow compounds such as methane to exist.

    Also note that there is form of covalent bond in which sharing is not the correct term to describe the role of electrons, simply one atom donates and the other accepts. These dative covalent bonds (coordinate covalent bonds) i supose are a sort of bordering point between the ionic and the covalent.
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  9. #8 Re: Keep in mind... 
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    Quote Originally Posted by AdmiralFloyd
    Covalent bonds are themselves categorized by strength. Sigma bonds are the strongest and occur between low orbiting electrons such that the participating atoms can remain in close proximity. Pi bonds are weaker for the reason that they involve electrons from outer shells.
    That’s not accurate. Whether a covalent bond is a sigma or pi bond depends on the geometry of the atomic orbitals that are overlapping to form the molecular orbital involved in the bond. Sigma bonds have direct “end to end” overlap, while pi bonds have “side to side” overlap. It doesn’t have anything to do with what shell the electrons are in, or how close together the atoms are. It’s true that a sigma bond will usually be stronger than a pi bond (assuming that the same orbitals are involved), but that’s only because you usually get more atomic orbital overlap with a sigma bond.
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  10. #9 ok 
    Forum Freshman AdmiralFloyd's Avatar
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    thanks for clearing that up scifor', i was unsure about it, between us i think we've answered goodgod3rd's questions
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