Caffeine/Talk

From Wikipedia

< Caffeine

HomePage | Recent changes | View source | Discuss this page | Page history | Log in |

Printable version | Disclaimers | Privacy policy

Pardon me for not keeping track, but what was the decision on images in wikipedia for things like molecule structures? I've just sent Larry a .png I created of the caffeine molecule, b/c the transcription on the main page looks so foreign to what I'm used to seeing--but I'm not a chemist, nor did I progress beyond CHM 2400. :-) Should we create our own images, or handle it through ASCII art? The advantage of images would be that some vandal can't come in and change, say, an "H" to a "C" and slip it through. The disadvantage is that some professor can't come in and change, say, an "H" to a "C" and have it be duly noticed. Also, the images won't display in text browsers. Opinions? --KQ


Without images, the web wouldn't be what it is; I say, go for the images.


Yay! that's the quickest turnaround on any request for a new entry that *I've* ever made! MichaelTinkler, caffeine-addict


That's because you're not the only caffeine addict here. :) -- Taw (who started Caffeine entry and is proud of it).


KQ, a professor could still come in and make a note that the depiction isn't right, and someone could just then go fix it and repost it. Right?


That's true I guess. The .png doesn't show up in IE 5.0 tho (or Opera 5.01), for some reason. It works in Photoshop, Irfanview, and NS 6.1. Any suggestions? Lee? Optimum format, preferences to toggle, etc.? --KQ

What PNG? IE 5.0 should be fine (See, for example, http://www.libpng.org/pub/png/pngsuite.html to verify your browser). If you can give me a URL for the actual file you're talking about, I'll see if it is a correctly coded image file. --LDC


The reason it doesn't show might be that there's no link in the article... --Magnus Manske


Since I can't work out (from the discusion above) whether anybody has actually made an image, I went ahead and made one for my favourite molecule. BTW I'm not really a chemist so I used the ASCII structure as a reference, somebody else should check it. -- DrBob


I have made an image, which I emailed to Larry, but I did something wrong and it doesn't work in IE 5.0. I'll send it to LDC so he can point out what I've done wrong, but right now I'm at work and the image is at home. Thanks for making an image of your own, but the diagram leaves out the individual carbon atoms, and also has a shape different from how it's usually drawn, because it's based on the ASCII art, which is limited to pipes and slashes to indicate bonds. I'll send the image to LDC tonight when I get home. --KQ


It was my impression that in schematic diagrams like this is was traditional to leave out the carbon atoms rather than clutter the diagram with what is otherwise obvious. Of course a more pictorial representation (such as a ray-traced picture with spherical atoms) has to leave them in. --LDC


Well, it's been a long time since CHM, but the only atoms I remember leaving out were the hydrogen ones. Is it customary to leave out the carbons, too? Anyone? --KQ


Well, I thought it was, which is why I left them out in the first place. I've certainly seen diagrams printed that way. But as I say, I'm not a chemist. -- DrBob


I'm seeing it half and half on a google image search. Maybe a chemist can come explain to us laypeople. :-) --KQ


There are lots of carbons in lots of compounds. We leave them out as often as possible -BUT we know what we are talking about. That may not hold for a general audience. -A chemist.


As a to-be-biochemist, it looks good to me. Definitely sufficient. --Magnus Manske


I'm not a chemist, or looking to be one, and it definitely wouldn't have been clear to me. Who is your audience, anyway?

We can't teach all of chemistry in the caffeine article, don't you agree? Those who know what the image means (at least roughly;) will welcome it, and the others should take a chemistry class! The image is additional, it is not the central part of the article. But, if you (whoever you are) would like to start a "how to learn chemistry" wiki, go ahead, I will contribute when I have some time :) --Magnus Manske

I'm not sure I agree. I know what the image means, but I wouldn't have guessed that there were Carbons at the intersection of each 4 bonds without a letter there--though, with the C listed, I could tell you that the C stood for Carbon. Is it a stylistic matter (some of the images do show the C)? --KQ

In chemistry texts, carbon atoms in rings are left out more often than not, especially aromatic rings like benzene but other rings as well, and occasionally in straight chains. The only real exceptions are when you want to point out optical activity and when you want to make it really, really plain what is happening. I think it would be better to explain the convention somewhere than to try and put carbons in everywhere - consider what will happen with chlorophyll and heme.

For a practical example when to draw carbons, see [1] for aspirin drawn with and without carbon atoms. I think the initial remark was about "images of Lewis structures are too complicated for the unwashed masses", though. Or am I mistaken? --Magnus Manske


That ring (the benzene ring) is, as they say, so common that it is usually drawn like that, but if you'll notice, the Carbons are still indicated in the attached molecule. --KQ

That's because the attachment is a straight chain, corresponding to the CH3 groups here, where carbon are shown. It is fairly rare, though not unheard of in larger molecules, for carbons to be omitted in straight chains, since it isn't quite as clear how to replace them.


Here's the image KQ sent; I don't have any particular preference, but someone might.

http://www.piclab.com/images/caf.png