Talk:3200: Chemical Formula

I'm disappointed that it wasn't scrollable. 2001:41D0:8:5062:0:0:0:1 20:20, 28 January 2026 (UTC)

+1 And funny to think that the universe contains less than a few hundred mol of Americium. --2001:16B8:CC03:E100:8552:6543:7CF4:9AE7 20:57, 28 January 2026 (UTC)

Time for a campaign to Make Americium Greater? 82.13.184.33 09:32, 29 January 2026 (UTC)

Some people don't understand sarcasm. Pleaze don't give them ideas. Gorcq (talk) 12:15, 29 January 2026 (UTC)

If anyone's interested in an accessible resource for getting more data like this, may I suggest https://ptable.com/#Properties/Abundance/Universe (which I believe derives data from IUPAC sources) Dextrous Fred (talk) 20:37, 28 January 2026 (UTC)

surprised to see so much Astatine, he himself declared, that stuff doesnt want to exist so I expected yet a few powers of ten less 2a00:6020:479f:6c00:d587:ac2a:d1e2:26a9 (talk) 21:08, 28 January 2026 (UTC) (please sign your comments with ~~~~)

This does make me curious: how would neutronium be represented in a chemical formula? Or would it be? My impression is it kind of exists 'outside' of chemistry... -Kalil 147.81.60.76 21:12, 28 January 2026 (UTC)

Neutron stars would be represented with n with various mass numbers. And there are no more than 1 mmol (6.02214076×10²⁰) of neutron stars. 2001:4C4E:1C09:EC00:7932:264E:A9E0:8ED0 21:38, 28 January 2026 (UTC)

What about adding mass numbers? For example, most of the hydrogen is ¹H, with small amounts of ²H and trace amounts of ³H. 2001:4C4E:1C09:EC00:7932:264E:A9E0:8ED0 21:38, 28 January 2026 (UTC)

Oh look, it's the 3200th comic! Yay I guess! --DollarStoreBa'al^Converse 22:46, 28 January 2026 (UTC)

An unregistered user (198.48.180.159) added a note that the chemical formula "C11H15NO2" (i.e. C₁₁H₁₅NO₂) "has 302 registered isomers". I don't know the source for that number or where those isomers are registered. (It's the formula for MDMA, which is, as noted, "not good to eat".) Would that be the CAS registry? BunsenH (talk) 23:20, 28 January 2026 (UTC)

Don't know if this works, but here's a site that does immediately return 302 compounds: https://pubchemlite.lcsb.uni.lu/compounds?query=C11H15NO2 8.17.60.225 04:19, 29 January 2026 (UTC)

10^26 atoms of americium is about 40 kg. But it looks like humans produced tons of americium: https://isis-online.org/uploads/isis-reports/documents/np_237_and_americium.pdf . If there are other civilizations in the observable Universe, then the amount of americium in the Universe is even higher. So I guess the formula counts only naturally produced elements. But even then it seems underestimated. Alexei Kopylov (talk) 23:45, 28 January 2026 (UTC)

In everything that I've checked (I expanded the "list of names" into a table), I could not discover any universal quantity of americium that was close to Randall's apparent source. Can't exclude the possibility that artificially nucleogenesis played a part in his figures (while mine are from how much was created 'naturally'), but I've just had to go along with it being a completely wrong figure (for the ultimate universal ranking). Much as boron might be given slightly mismagnituded.

However, if anyone thinks they have the same source that led to the comic's values (and can reconfirm beryllium's estimated order of magnitude, which is the only reason I decided to start on compiling this amount of extended data, which is actually for all 118 humanly known elements), then you're welcome to correct anything that I left in an incorrect state. 81.179.199.253 00:16, 29 January 2026 (UTC)

...but what if you had a mole of universes? 99.109.3.237 (talk) 00:50, 29 January 2026 (UTC) (please sign your comments with ~~~~)

In the explanation, towards the end of the formula for the universe, it says U₁₀². Would that mean that there are only about 100 uranium atoms in the whole universe? That seems way too low. Did the explainer confuse the powers of 10 with rankings (in reverse)? --208.59.176.206 03:48, 29 January 2026 (UTC)

I'm not sure where the error came from, but about half the numbers are drastically too low. Remember, a mole is 6.02*10^23. 174.94.104.215 05:34, 29 January 2026 (UTC)

Fixed. The powers were just in descending order, one by one. The current values reflect the actual amounts, give or take one or two orders of magnitude. --1234231587678 (talk) 06:04, 29 January 2026 (UTC)

In the first paragraph of the explanation it says that the number for helium would be about a third as the number for hydrogen. This seems to compare the total masses for both elements instead of the number of atoms. Hydrogen should account for aprox. 92% of the atoms while Helium is approx. 8%. 2A02:810D:9B99:7800:DECB:CADA:B418:2F1A 05:58, 29 January 2026 (UTC)

A very good point. It seems that some sources just neglect to clearly specify whether they're giving abundance in mass fractions or mole fractions (or relative mass totals/mole totals/etc), so probably where errors crept in. But by looking at H and He, if they are roughly 74% vs 24% then it's probably by mass, and the figures probably need adjusting down by the (typical) Z of that element. (So, a third of the mass should be a twelfth of the number, and 12x8%=96%; not far off being 8% vs 92%, well within the casual rounding errors we have accumulated.) If/when I've time, I'll maybe do suitably adjusted values wherever they're needed, but can't do it immediately. 82.132.239.10 15:02, 29 January 2026 (UTC)

Re "Other more complex atoms, up to atomic mass 56, formed later ... as a result of stellar nucleosynthesis". Not all of them; there is another way. Boron and Beryllium are produced by cosmic ray spallation, the splitting of heavier atoms by the impact of energetic particles. 2A12:F43:141A:9F00:A0FA:9260:7BAF:8D57 13:16, 29 January 2026 (UTC) dww-uk

How do we count the atoms that all rollled up into a singularity and otherwise vanished from the universe except to leave a big pinch in it that causes weird gravity effects. 130.76.187.47 13:37, 29 January 2026 (UTC)

I'd say that's a "hairy" problem. 82.132.239.10 15:02, 29 January 2026 (UTC)

Off topic, but didn’t Xkcd used to be daily? Commercialegg (talk) 14:50, 29 January 2026 (UTC)

Not really.

There have been 'special weeks', the latest being 822: Guest Week: Jeph Jacques (Questionable Content) to 826: Guest Week: Zach Weiner (SMBC) (with previous all-weekday seqeucnes being "The Race", "Secretary", "1337", "Choices" and "Parody Week"), and a spottier schedule back in the double-digit comics that weren't so strictly (or necessarily restricted to) the M/W/F schedule, and April Fools might come out on the relevent day (although also often on whatever day they were eventually ready!), as per other seasonal comics or ones tied to book-releases/etc.

Of course, every day is an xkcd day. As well as every day there's an xkcd (but of course its generally the same one as came out/should have come out on the prior Monday/Wednesday/Friday release scheduled), and always something to learn... ;) 81.179.199.253 18:58, 29 January 2026 (UTC)