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Thread: What is Hydrogen??

  1. #1 What is Hydrogen?? 
    Genius Idiot Rajnish Kaushik's Avatar
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    Is it an halogen or Alkali metal?


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  3. #2  
    Brassica oleracea Strange's Avatar
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    It is obviously not a halogen (wrong group).

    It is usually put in the same group as the alkali metals but it is not a metal (it's a gas). Because it rapidly forms stable diatomic molecules, it doesn't show the same reactivity as the alkali metals but I think monatomic hydrogen is pretty reactive.


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    Bullshit Intolerant PhDemon's Avatar
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    I can see where the question is coming from, on some versions of the periodic table it is put with the alkali metals (as it has one valence electron like Group 1), in older tables I have seen it put with the halogens (as it has one electron less than a filled valence shell - like Group 7). Although it has some similarities to both groups it's unique in that is has both one fewer electron than a filled valence shell and one electron in it's valence shell so I would class it as neither and treat it as a seperate "group" in it's own right.
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    This video might be over pedagogical, but there is some explosions. And dig that dudes hair!
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  6. #5  
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    Quote Originally Posted by Strange View Post
    It is obviously not a halogen (wrong group).

    It is usually put in the same group as the alkali metals but it is not a metal (it's a gas). Because it rapidly forms stable diatomic molecules, it doesn't show the same reactivity as the alkali metals but I think monatomic hydrogen is pretty reactive.
    In fact, to an astronomer, it is the ONLY element that is NOT a "metal". They're all mad, you know……...
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    It's theorized that at very high pressures Hydrogen has a metal phase; Metallic hydrogen - Wikipedia, the free encyclopedia
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    Quote Originally Posted by Strange View Post
    It is obviously not a halogen (wrong group).
    The term "pseudohalogen" is used to describe substances that are not halogens but bear a formal similarity to them. An example of a pseudohalogen is cyanogen with the cyanide ion being the corresponding pseudohalide. I don't know if hydrogen is classed as a pseudohalogen although the hydride ion ought to be considered a pseudohalide.
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  9. #8  
    Genius Idiot Rajnish Kaushik's Avatar
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    ok
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    i'd say it has it's own group
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  12. #11  
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    It resembles with halogens in reactivity and resembles with alkali metals in electronic configuration but unlike halogens and alkali metals hydrogen fails in many aspects,hence it is neither halogen nor alkali metal,it is an unique element
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  13. #12  
    Genius Idiot Rajnish Kaushik's Avatar
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    ok so can we make a new category for it?
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  14. #13  
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    Quote Originally Posted by chinna View Post
    It resembles with halogens in reactivity and resembles with alkali metals in electronic configuration but unlike halogens and alkali metals hydrogen fails in many aspects,hence it is neither halogen nor alkali metal,it is an unique element
    I don't think you can say hydrogen resembles halogens in reactivity. It behaves quite differently. For example halogens are strongly electronegative, forming anions very easily, while hydrogen is the opposite, electropositive, tending to lose an electron to produce the hydrogen ions which are so ubiquitous throughout chemistry. Hydride ions are rare and are highly reactive in most situations.

    Hydrogen is unique really but if were forced to put it somewhere in the Periodic Table I would do so according to its electronic configuration, i.e. above the first of the alkali metals. Classing it as a pseudo halogen makes little sense I think.
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  15. #14  
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    Re: "Making a special class for it". I'm not a chemist, but rather a literature major. But making a special class for a single element is an abuse of language. If there is but a single example of the thing you propose putting in the "class" then there is no need for a "class". It is just itself. To talk of a class of one is to unnessessarily complicate the issue.
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    Brassica oleracea Strange's Avatar
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    Never heard the phrase, "in a class of its own"?
    And what happens if you are the only passenger in the first class carriage of a train; the carriage disappears?
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  17. #16  
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    Quote Originally Posted by Rajnish Kaushik View Post
    ok so can we make a new category for it?
    Well yes, sort of. But I think it's terribly important not to overdo the understandable wish to classify every element into groups. The Periodic Table was a wonderful invention and is enormously helpful to make sense of what goes on in chemistry and to enable predictions, but in the end no two elements are really alike. Some versions of the Periodic Table show H and He in a separate box, due, I suppose, to the absence of any valence shell electrons other than s type.

    Personally I think that, if you want to think of hydrogen in terms of the classifications in the Periodc Table, then the best way to do so is to (a) position it as the first of the s block elements, i.e. above the alkali metals, but (b) also keep in mind that the dramatic fault line of the metal/non-metal diagonal runs between it and the alkali metals. So its paradoxical nature is that it is the sole member of the "alkali metals" group that is not a metal!
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    Quote Originally Posted by Sealeaf View Post
    Re: "Making a special class for it". I'm not a chemist, but rather a literature major. But making a special class for a single element is an abuse of language. If there is but a single example of the thing you propose putting in the "class" then there is no need for a "class". It is just itself. To talk of a class of one is to unnessessarily complicate the issue.
    I think that's a bit harsh. The nature of the classifications we as chemists are trying to formulate is to define classes of element such that we can predict the ways in which we expect them to resemble others and the ways in which we expect them to differ. Making a new class for one element might not be trivial if, by doing so, we can draw attention through the classification system to some predictive attributes. To take an example from zoology, it means more to say the duck-billed platypus is a monotreme than to say it is just an exception to the rules for classifying mammals.
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    Hydrogen reacts like a metal when its a salt.. However when you look at states and other properties it reacts like an alkali metal, but not an actual metal. It does seem like a nonmetal when it forms organic compounds.

    To me it seems so small to be an atom, lets just call it an enriched proton (with electron), and change the periodic table.
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  20. #19  
    Genius Idiot Rajnish Kaushik's Avatar
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    ok thnx for that
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