Periodic table gets weighty update

The atomic weights of 10 elements will be changed to ranges instead of definite numbers to more accurately reflect the way they are found in nature.

Pocket periodic table
Let me tell you, this baby comes in handy...well...almost never. Josh Lowensohn/CNET

In the biggest development to rock the popular-science world since Pluto got demoted, 10 elements will see their atomic weights changed on the periodic table.

With the news, oversize posters and textbook inserts around the world (not to mention the tiny periodic table I've been carrying around in my wallet since the ninth grade) are about to become outdated.

The reason for the change is that atomic weights are not always as concrete as most general-chemistry students are taught, according to the University of Calgary, which made the announcement, and the snappily named International Union of Pure and Applied Chemistry's Commission on Isotopic Abundances and Atomic Weights, which oversees such weighty matters.

Certain elements have more than one stable isotope, which means they can appear in nature with different weights. In its statement today, the organization gave the example of sulfur, which is typically listed as having an atomic weight of 32.065 but which can actually weigh anywhere between 32.059 and 32.076, depending on where it is found.

As a result, the Table of Standard Atomic Weights will now show a range of weights--rather than one fixed atomic weight--for hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, and thallium.

While this change will make the periodic table a more accurate reflection of how elements exist in nature, it could make teaching basic chemistry a little more complicated.

"Though this change offers significant benefits in the understanding of chemistry, one can imagine the challenge now to educators and students who will have to select a single value out of an interval when doing chemistry calculations," said Fabienne Meyers, associate director of the IUPAC.

"We hope that chemists and educators will take this challenge as a unique opportunity to encourage the interest of young people in chemistry and generate enthusiasm for the creative future of chemistry."

The man who dared to invalidate giant posters in chemistry classes around the world, Michael Wieser, a scientist from the University of Calgary who is helping to update periodic table. Riley Brandt/University of Calgary

So, other than those of us who startle at the notion of such a staunch figure in the chemistry world being changed (and the schools that now have to replace their posters), what does this announcement mean for the average Joe? Probably not much, if the frequency with which I whip out my trusty mini-periodic table is any indication.

But, as Meyers says, it could give teachers an opportunity early on to school students in the nuances of basic chemistry. As an example, in today's announcement, the University of Calgary explained how atomic weights are much more than another data point for high school chemistry students to memorize.

In fact, the ability to measure isotopes can be used to determine the purity and source of food, such as vanilla and honey; to trace pollutants in streams and groundwater; and to identify performance-enhancing testosterone in the human body.

I think I'll still hang on to my card, though--just for old time's sake.

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About the author

Jennifer Guevin is managing editor at CNET, overseeing the ever-helpful How To section, special packages, and front-page programming. As a writer, she gravitates toward science, quirky geek culture stories, robots, and food. In real life, she mostly just gravitates toward food.

 

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