[tnbp]

>I was looking at the Wikipedia article on aspartame when I realized that there was a significant error on the page. The skeletal formula was correct but the ball-and-stick model was incorrect in that it had an extra hydrogen tacked onto the aspartic acid group—the NH2 was misrepresented as NH3.

I am sure you meant well, but as far as I can see, the original ball-and-stick model was indeed correct--and the current edited version is wrong. Amino acids, as well as most things made from amino acids, exist as zwitter ions in solid form as well as in aqueous solution. The carboxyl groups are comparatively strong acids, the amino groups are comparatively strong bases, so there is a proton transferred to NH2, making it NH3+. That proton is missing from the carboxyl group resulting in a carboxylate group (COO-). The positive and negative charges cancel each other and the result is a zwitter ion with two charged atoms/groups, but no charge overall. The newer version still has a carboxylate group (COO-), but no NH3+ group, making it negatively charged. That probably exists, at high pH values.

[hilbert42]

What I didn't mention was that I double-checked in case I was going crazy, so I crosschecked on ChemSpider: https://www.chemspider.com/Chemical-Structure.118630.html - see 3D model (presumably it's also incorrect).

I've yet to check Wiki as of today, so I don't know if the site has changed since last August or not. I will check momentarily.

I acknowledge what you say and I'm not necessarily disputing your points. If this is the result of another of the many nomenclature problems that plague and beset chemistry then I'm damn-well sick of it (and I'm certainly not alone).

It's about time that someone—some authoritative body, most specifically IUPAC et al, sorted this mess out.

PS: you haven't really answered why both the skeletal and ball-and-stick would be different. Moreover, the skeletal outline in the story is also the usual default (i.e.: the same as in both versions of Wiki and in ChemSpider).

[tnbp]

IUPAC has nothing to do with it--aspartame is a trivial name. It's no mess, either--chemists know that 1M sulfuric acid does not contain any H2SO4, even though H2SO4 is sulfuric acid. The skeletal and ball-and-stick structures differ precisely because they weren't created from the same source--the author of the ball-and-stick structure cites a crystallography paper as their source, and solid crystals consist of zwitter ions.

[hilbert42]

That type of problem is found throughout chemistry but usually an accepted nomenclature applies (when it doesn't is when we get into troubles).

So why did Wiki make the change when I pointed the matter out if it is incorrect?

I'd now suggest you get it corrected.

Edit: also tell Wiki that it shouldn't post inconsistent information as it only confuses (similarly ChemSpider).

Edit 2: 'aspartame is a trivial name'. Very true, but aspartame is not known to the world by its IUPAC name, even at best it still means that a nomenclature problem exists.

[tnbp]

  >That type of problem is found throughout chemistry but usually an accepted nomenclature applies (when it doesn't is when we get into troubles).

It is not. Nobody who is into chemistry is confused by it, and those who are usually learn something new when they first stumble upon it.

  >So why did Wiki make the change when I pointed the matter out if it is incorrect?

Possibly because most Wikipedians aren't chemists and assume good faith.

  >I'd now suggest you get it corrected.

That level of entitlement...

  >Very true, but aspartame is not known to the world by its IUPAC name

Please think about this statement. Thoroughly.

[hilbert42]

There's no point in me continuing this discussion with a closed mind.

No offense intended.

[tnbp]

Indeed there isn't. It isn't a discussion either--you asked a question, which I answered, while you continued to argue from ignorance.