Tuesday, December 30, 2014

Periodic Table with {wildly inaccurate} EMPHASIS

Studies show that scientists and those interested in science are susceptible to misinformation contained in memes.1 In 1976, William Sheehan published an article entitled "Periodic Table with EMPHASIS".2 This publication remained virtually undiscovered for 36 years until a series of events appears to have brought this obscure document to the forefront of chemical (mis)information. A Google investigation suggests that a Tumblr user posted a periodic table graphic with the caption "Totally in love with this image". The Radiolab Tumblr reposted the illustration, and finally io9 posted the image on its website. The unique version of the periodic table has been tweeted, retweeted, shared, +1 and liked into viral status,3 which would be quite a coup except that no one in the initial series of postings appears to have investigated or critically analyzed the veracity of the science this periodic table purports to illustrate. 

Two versions of the "Periodic Table with EMPHASIS". The version that appeared in 2012 and was subsequently went viral (top), and the original version from the article (bottom).

Take a look at the graphic (top). Anyone with sufficient background in rare elements will immediately spot problems with this periodic table (more on that later), but it's easy to see why this caught people's attention. You could get a contact high from the vintage LSD that the previously normal periodic table dropped before having its picture taken. This is probably what Salvador Dali would have produced if the periodic table commissioned him to paint its portrait. As my good friend and frequent co-author Brett mused "It looks very retro...You can smell the early 70s from the unshaven armpit between Y and Zr." After explaining on twitter for the umpteenth time that the information in this graphic was terribly wrong, I ordered the source paper through interlibrary loan.4 The original version of the picture is less striking as it lacks the color scheme (bottom), which as an aside does not correlate exactly with any normal categorization of elements.5 While it is unclear exactly who modified the original, the tie-dyed version was the one posted on Tumblr in 2012. 

To defend Sheehan, I don't believe he intended this to be anything other than a thought experiment to stimulate interest in the periodic table with children. The "paper" contains almost no information on how it was constructed. The only citations are to papers on other artistic versions of the periodic table from the educational literature. The article is 1 1/2 pages long. The bottom half of the 2nd page contains two poems 
written by high school students – one a ballad on Mendeleev and the other an ode to chemical bonds. The page also contains two separate lists of chemical puns. Not exactly the material you find in most scholarly journals, but a staple of internet science. I am unsure of what kind of publication Chemistry was, but the Sheehan "paper" has never been cited according to Scifinder. The composite evidence suggests that the article is from a magazine targeted toward a more general audience, not a peer reviewed journal.

So, what are the most egregious errors in this table? 
Tc (Technetium, element 43), At (Astatine, element 85), and Fr (Francium, element 87) are the most striking. At occurs naturally as a product of uranium and thorium radioactive decay, however, the half-life of all At isotopes are so short that less than 30 g of the element exists at any time on earth. A similar amount of Fr exists for analogous reasons. Their neighbors Po (Polonium, element 84) and Rn (Radon, element 86) exist at approximately 10-10 and 10-13 mg/kg in the earth's crust respectively. Small numbers certainly, but still 7 orders of magnitude greater than the estimates for At or Fr. The element boxes in the image are roughly the same size, not 10 million times larger.6

I discussed the table's problems with my friend Brett. His musings:
"Did I say that that table was actually impossible to display on a computer monitor correctly? I checked the math. It's amusing:

For argument's sake, let’s say that naturally occurring Tc is 10-10 the amount of U (Uranium, element 92). There are about 6 orders of magnitude less U in the earth’s crust (at least) than O (Oxygen, element 6) or Si (Silicon, element 14) the 2 most abundant elements. So there is 10-16 less Tc than O in the earth. I think this overestimates the amount of Tc, but 10-16 is bad enough.

To have a visible block for Tc requires how many pixels? If you want to read the "Tc" symbol, you need at least a 6×6 pixel square by my estimate. 36 pixels for the smallest element "block" on this hypothetical table. That means the largest block (O) would have (roughly) 3.6×1017 pixels. I don't have the motivation to figure out the exact size of all the other element blocks, but the earth's crust is dominated by just a few elements, so let's say that the total pixels required for the table would be about 2×1018 pixels (this is the worst estimate in this calculation, but it would take longer to calculate exactly and it's not off by more than an order of magnitude).

I'm typing this on a screen with 1920×1200 pixels, or about 2.3 million pixels. At the same resolution as my monitor, to be able to SEE the Tc element block, the monitor would be 8.68×1011 times larger. Yes, the screen would need to be 868 BILLION times larger.

I think there MAY be enough pixels on all the monitors in the world to do this. Especially now that there are so many smartphones around. Right? A little Googling reveals that in March 2014 Apple sold the 500 millionth iPhone. Let's be generous and assume that all iPhones to date had the large high-res screen size available at that time, 1136×640 pixels (A slightly bad assumption, but since each iPhone has outsold its predecessors, not a terrible assumption). So each iPhone has 727,040 pixels. The block for oxygen would require 495 BILLION iPhones to display. The entire table would require about 3 TRILLION iPhones to display.

Yikes. Looks like smartphones are still a growth market."

So just like every other meme and viral post, take things shared on the internet with a grain of salt until you do some research. Fortunately, Google has a better version of the periodic table by relative abundance. Not as groovy as the Sheehan table, but more accurate. Our analysis of the problems with the graphic are by no means comprehensive. I would encourage readers to highlight their pet peeves about the table in the comments, so this post can be a resource to educate people about the true natural distribution of the elements.

Update: 7:32 PM 12/31/14
Here are a couple of other representations of the periodic table showing abundances. These cartograms are both aesthetically appealing and informative. This one by geochemists is also interesting if not all that artistic.

Update: 3:47 PM 1/2/15
Here is an in memorium from the Santa Clara University website on William Sheehan that references his periodic table graphic. Further updates or a new blog will be posted if/when I can track down further information.

Update: 11:25 AM 1/3/15
EUREKA! After doing a lot more digging and coming up with very little from Santa Clara University, I found a J. Chem. Ed. paper from 1993 by Kathleen Carrado at Argonne. It's copyrighted material and behind a paywall. The article discusses using a black and white version of the Sheehan table as a coloring book exercise with elementary-aged students. The paper also references a 1978 calendar by Instruments for Research and Industry that used Sheehan's graphic. Confirmation pending, but this seems like where the colored graphic originated, and further proof that this table was not intended to be an absolute representation of relative abundance.

Update: 11:34 AM 1/4/15
Another calculation analogy from Brett:
A properly scaled table would cover an area of about 3×1012 × ((58.6/1000)*(123.8/1000)) m2, or 21764 km2 or 8403 square miles. That’s an area about 7 Rhode Islands or 80% of the size of Massachusetts. Kind of hard to carry around or print out 

1. This is an anecdotal observation made by one blogger, which seems to be sufficient evidence of validity in the internet age.
2. W. F. Sheehan. Chemistry. 197649, 17-18.
3. What counts as viral in the chemistry world anyway.
4. I would post the paper in total, but this would probably violate copyright law. How about a link to the pdf in Google drive instead?
5. Colors correspond to relative electronegativity. This has been clipped off of some of the images being circulated. Also, the colors do not accurately represent electronegativity. See here. For example, Kr and Xe have approximately the same electronegativity as their halogen neighbors. 
6.  The Sheehan graphic has the disclaimer "To accommodate all elements some distortions are necessary. For example, some elements shown do not occur naturally", but does not provide details. The transuranium elements fit the latter characterization, nevertheless 7 orders of magnitude seems like a broad interpretation of "some distortions."

Friday, October 10, 2014

Protactinium’s Discovery Redux: Kasimir Fajans and Oswald Göhring discovered element 91 in 1913

The great Periodic Table of Videos series on YouTube a few weeks ago published a video on element 91: protactinium. Protactinium is an element that is (a) obscure and rare (b) has a confusing discovery story, and (c) had linguistic issues with its name. Given our interest in discovery, isotopes and nomenclature, we found a few details in the video that should be revisited. For an element such as protactinium, which has few applications today, an element’s entire “story” concerns how it was discovered.

The Periodic Table of Videos series is exceptional, but things go slightly awry beginning around 3:00 in the protactinium video with the still frame of Frederik Soddy & John Cranston. These two British scientists, along with Lise Meitner & Otto Hahn of Germany, are credited with the discovery of protactinium. That’s incorrect: Meitner & Hahn published their successful precipitation of element 91 in 1918, but this was not the discovery of the element—it wasn’t even the first precipitation of the element. The independent work of Soddy & Cranston, also published in 1918, also was not the true discovery.

Starting around 4:00, the professor explains that the isotope 238Pa, which has a 32,760 year half-life, was discovered by Meitner & Hahn and “a few years earlier” Kasimir Fajans discovered 234Pa. 234Pa has a much shorter half-life and was named “brevium” (Fajans’ co-discoverer Oswald Göhring is not mentioned).

Shouldn’t Fajans & Göhring be the credited as the discoverers of element 91? They beat Meitner & Hahn and Soddy & Cranston by five years! In 1913, Fajans & Göhring had three separate publications on element 91 including the precipitation of 234Pa (K. Fajans & O. Göhring, Phyik. Z., 14, 877, 1913). This work is discussed explaining “[Fajans'] was the first discovery of protactinium, but it turns out that there is a custom if several different isotopes of an element are discovered, whoever discovers the longest lived isotope, wins, and they’re deemed the discoverer.” Wait, what??? That sounds like redefining the word “discovery”!

What is explained in the video is only half the story. The other half is that Kasimir Fajans pushed the idea that the elements should be given the name of the longest lived isotope (in his 1919 book Radioaktivität und die Neueste Entwicklung der Lehre von den Chemischen Elementen). In the 1910s, isotopes were a very new idea and it was still unclear whether or not they should be treated as separate elements. Meitner & Hahn’s 1918 paper clearly claims a new “element” even though they knew they knew that their “element” had the same atomic number as Fajans & Görhing’s “element” discovered 5 years earlier. Meitner & Hahn were using the definition of the word “element” as was common in 1918 when it was still unclear how to classify isotopes. When chemists say “element” today, they clearly mean all isotopes with the same atomic number. Fajans never intended to give away the credit for element 91’s discovery to Hahn & Meitner or Soddy & Cranston. In fact, one of Fajans’ last papers defends his discovery priority.

There is one other element that was renamed based on its longest-lived isotope: radon. Radon’s discoverers wanted to call the element emanation. For decades, “radon” was only the name of the longest-lived isotope of emanation. After the name was changed, history began to forget who had actually discovered radon. Just like protactinium, people preferred to give credit to the individual or group who had discovered and named the longest-lived isotope of the element. We wrote quite a bit about the linguistic twists of radon last year in Nature Chemistry. In an accompanying blog post, we explored protactinium’s naming and discovery confusion. There is also an excellent Nature: In Your Element piece that delves into the protactinium story.

Is there is a lesson here for chemists? If you get to name something, you might get credit for discovering it, even if you didn't. That can happen both inside and outside of chemistry, which might be a more than a little disconcerting.

It’s incorrect to say that “the discover of the stablest isotope gets to name the element” as a general rule, especially today. Since most superheavy elements are created as highly unstable, neutron-poor isotopes first, only later are (slightly) more stable isotopes created. No one is ceding naming or discovery priority to anyone who years later makes the most stable version element 112 for example. The Periodic Table of Videos project is great and everyone should follow their work, but examine the protactinium discovery a little more closely to get the complete story.

Brett F. Thornton with editorial assistance by Shawn

Monday, February 10, 2014

Winning the "War on Chemicals" by redefining victory

With some rudimentary photoshop skills I could appropriate one of Stephen Colbert's "War On _____" graphics as a post banner. Alas, I have none.

With clock-like regularity, some synthetic compound bearing the unnerving label "chemical" is brought to the public's attention. To make matters worse, the "chemical" also is identified by its proper name, an intimidating number of consonants and vowels jumbled together into a seemingly incomprehensible order to the untrained eye. The end result is most often a demand that the offending substance be expunged from existence because of the inherent risk in coming into contact with "chemicals." The public's irrational fear of chemicals has been dubbed chemophobia, which is also a popular hashtag for connecting discussions of the subject online.

The most recent dustup involves the use of azodicarbonamide in Subway's flour/bread. This instance has all the hallmarks of chemophobia: bad analogies, (wildly) exaggerated claims of health risks, insinuations of conspiracy. Chemists immediately took to twitter and blogs to defend chemicals and debunk claims that led Subway to decide to phase out azodicarbonamide. In the Pipeline had previously summarized why the risks of using azodicarbonamide are extremely small, and the Curious Wavefunction discussed the real danger of chemophobia. The response is typical of how we chemists have combated these controversies, and we are losing.

As people who spent an inordinate amount of time in institutions of higher learning (including as a career), the "defend and debunk" strategy comes quite naturally. We like education and educating. Being scientists also makes exploiting this tactic even more amenable because we've been trained to collect, analyze and interpret data. When we see dubious claims or "chemical-free" products, our instincts take over and we make solid arguments backed by science; however, we are not engaged in a scientific debate with paper reviewers or grant referees. As has been documented previously, facts don't matter in these situations. When presented with evidence that a belief is demonstrably wrong, people often become more entrenched in their position. In order to defend chemistry, we need to change course and redefine what constitutes winning an argument. What strategies should we employ? Here are some ideas, but there certainly need to be more.

As the Curious Wavefunction alludes to, the biggest problem is when fear subverts the solutions to problems that science has produced. Feeding the world's +7 billion (and growing) people using only organic farming is almost certainly impossible. It has even been suggested that much-maligned GMOs will be necessary to produce enough food on a planet suffering from the adverse effects of climate change. These are more global versions of the problems science and chemistry has produced to deal with problems of food production, distribution and storage that are essential to modern lifestyles. In the discussion of azodicarbonamide, I have only seen passing references to its use as a flour conditioner, but not a justification. Oxidants like azodicarbonamide are used to oxidize sulfhydryls in gluten to disulfides. This conditioning ultimately speeds up flour processing, which historically was accomplished by the oxygen in air and takes weeks. As a non-food chemist, I conclude that azodicarbonamide was developed in the 1960s as a replacement for bromate as an oxidant. Bromoate, like azodicarbonamide, is banned in the EU, but it is unclear (to me) what has been adopted instead.

In a case like this, the discussion should be about the process and whether or not it is the best one available. Clearly, multi-week air oxidation of flour is incompatible with modern demand and production limitations, but azodicarbonamide is also +50 year old technology. While the risks may be small (or non-existent), is there an equally effective (or superior) alternative that would be more appealing to the public? The advantage of the alternative need not be limited to public perception, they could easily be more effective, efficient or cost-effective. As Carmden Drahl tweets, this may best be viewed as an opportunity to develop new chemistry and employment opportunities. Instead of focusing on the fear aspect, overcoming chemophobia may be easier by emphasizing the benefits of the chemical process and engaging in conversations about the alternatives. Such discussions may better illustrate what the safest option is, as well as why chemistry is essential. This may even be more convincing ways to show that the current methods were actually chosen because they are the safest/best.

The language and tenor of debate also does not help to advance the cause. When someone calls for a "chemical free" version of something, chemists are quick to point out that everything is composed of chemicals. There is even a line of t-shirts and posters that aim to show everything, including the humble banana, is nothing more than a complicated mixture of chemicals. While this is unarguably correct, this undoubtedly comes across as condescending and put those propagating erroneous information on the defensive. As indicated above, this will only serve to further entrench these people into the "anti-chemical" camp. Chemists are not particularly renowned for PR and marketing skills, but the chemophobia problem has more parallels with politics than science. To shift public opinion, we must be able to change the perception of chemicals. A better approach may be to suggest an alternative to "chemical-free" for the specific case without the condemnation. We like to be right, but proving we're right is losing the debate.

This brings us to the central thread of this debate, chemophobia. Like "chemical-free," the objections to synthetic additives based on uninformed opinions can undoubtedly be classified as an irrational fear. "Chemophobia" is certainly an accurate moniker that quickly summarizes what is, or what we believe to be, the basis for someone's objections to a chemical like azodicarbonamide; however, even though it's a relatively new term, chemophobia has already become a pejorative. Name calling and insults seldom (never) persuade someone to a different point of view. Godwin's Law could readily be applied to chemistry where every argument ends when we call someone a chemophobe.