Monday, August 31, 2009

Say Hi to the Molecule

molecule, pentacene, atoms
That is the very first ever picture of a molecule- pentacene, to be exact. The hexagonal shapes are the carbon rings, and the blurry white bits above them are the hydrogen atoms. For perspective, the space between the carbon rings is 1,000,000 times smaller than the diameter of a grain of sand.

Very, very cool.

9 comments:

  1. That has to be the coolest thing I have seen in a long time.

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  2. Hello Mr. Molecule. Now can we destroy it or use it to destroy people not like us?

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  3. Does anyone know the answer to this question:

    Reading the article, I see the picture of the molecule. Super cool. I also see the text book diagram of what this molecule looks like. I am amazed by of alike they look. So, my question: Did we know before that a picture of the molecule would look like the textbook diagram? Is this a huge confirmation of our understanding of how atoms and molecules work, by now actually having this picture? Or, did the process required to take the picture somehow force the molecule into this shape?

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  4. I think we just understood through other avenues what molecules would look like. we've seen this before in science, the prediction of something's attributes before actually seeing them.

    although, heisenberg's uncertainty principle . . . fucks everything up.

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  5. I'll try and answer my co-named's question.

    Pentacene is an organic aromatic molecule made from five benzene rings connected linearly. Any molecule containing a benzene ringis aromatic by definition. What's so special about a benzene ring? Well, it's formula is C6H6. It's carbon atoms are arranged in a hexagonal ring. Now, number the covalent bonds in the ring (is the sides of the hexagon) clockwise from one to six. Looking at the periodic table will reveal that carbon has a combining capacity of +4. This means that it can share four of its electrons in covalent bonds with other non-metals. Each carbon atom in benzene is bonded to one hydrogen atom, and since the carbon atoms are in a ring, these account for three of the shareable electrons. What happens to the fourth? In order for each carbon atom to share four electrons, single and double bonds must alternate through the ring. This implies that there are two choices on where to put the double bonds; at the odd numbered sides of the hexagon (1, 3, and 5), or at the even numbered sides (2, 4, and 6).

    Using spectroscopes, chemists have determined that double covalent bonds are shorter than single covalent bonds. Doing the same with benzene reveals that the bonds are the same length? What does this mean? It means that the excess shared electrons are not in any particular bond. Instead, they are delocalized and in all of the hexagon's sides simultaneously. Benzene can hence be thought of as having a bond and a half between each carbon atom.

    Since there is a band and a half between each carbon, this allows us to remove the hydrogen from two adjacent carbon atoms. If we do this with another ring, this allows us to put the two rings together and make a new molecule. Repeating this process (possibly using another molecule that already has two bensene rings) allows up to put an arbitrary number of benzene rings together to make pentacene. (The reaction just described is actually an abbreviation of a series of reactions that produce excess "junk" on the benzene ring; further steps removes this junk and lets us put benzene rings together).

    In short, we know pentacene is this way because we know it is made of benzene rings. We know that the benzene rings have not been destroyed since there are no "missing" hydrogen atoms that would have to be accounted for if the benzene rings were destroyed. We do that through measurements of amount of substance.

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  6. Heisenberg makes me want to run around, waving my arms above my and laughing like a joyous maniac, while simultaneously rocking in the corner in a tight fetal position. I *heart* him.

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  7. @ Rob F,

    Oh, right, magic. Got it! :)

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