Viewing the Story of the Development of the Periodic Table as “Getting it Less Wrong”

Tu-Anh Vu's picture

Men possess an innate need to understand things.  For this to happen, the process of categorizing and explaining relationships are use.  The “loopy scientific method” is the core procedure in which men apply to categorize things.  Using this loopy scientific method assumes that the summary of observations receive after the experiment is done, is not a final answer.  Since new observations can appear that might refute the old observations thus one can call it “getting it less wrong.” This idea of “getting it less wrong” can be applicable to the field of Chemistry, in this case the Periodic Table.  Although Chemistry can be considered as a science branch that is relatively more concrete than Biology, due to the possibility that experiments can be perform under controlled environments in a laboratory to confirm summaries of observations, it is never-the-less theories and not facts.  In this paper, I will make an argument stating that the Periodic Table is a man-made product that follows the loopy scientific method, thus can be considered as something that is “getting it less wrong” compared to earlier tables.  One can also consider it as a specific view, out of many possible views, on the relationships of elements though it is the most useful.  With this in mind, the Periodic Table is not a scientific truth but a good and useful chart of observations. 

Theories on evolution are the product of efforts from numerous scientists, but the credit is given to Darwin.  The development of the Periodic Table is similar to this, where Mendeleev is dubbed “father” of the Periodic Table.  But it is in fact the work of several scientists through trial and error that has given the Table its present form.  With the discovery of many elements, approximately sixty, scientist desired for a way to organize them. 

John Dobereiner led the way to a method to find order amongst the elements in 1829 as his hobby since theoretical scientific speculation was booming thanks to the encouragement of achievements from the Industrial Revolution.  This German chemist presented his theory of the Law of Triads.  From his observations of atomic weight of element bromine, which lies between that of chlorine and iodine (the same pattern can be found in atomic weight of strontium, which lay halfway between calcium and barium), he concludes that there is a relationship between these elements in that the middle element in the triad (the name given to the groups) consist of an atomic weight that is the average of the other two elements in that group.  Dobereiner’s Law of Triad is incomplete since his law only applied to a few elements and not the sixty, thus his law is view as a coincidence by fellow scientists.  One can see that this is the start to the loopy scientific method, because Dobereiner’s observations are not in-depth and lack support. 

Alexandre Beguyer de Chancourtois continues the path to find order within the elements.  In 1862, he propose his theory about the “telluric screw” to describe the relationship between the known elements.  This “telluric screw” consists of a cylinder on which was drawn a descending spiral line.  At intervals along the line, he would plot each element according to its atomic weight (he also mistakenly plotted some ions and compounds- these are not considered as elements).  He concluded from his observation that the properties of the elements would repeat itself when read off in vertical columns down the cylinder- after every sixteen units of atomic weight the properties of the matching elements exhibit similarities with the ones vertically above them.  This would seem like an unbiased summary of observation but from Paul’s tree of the loopy science method, the path from summary needs replacement back to summary of observations one will encounter “the crack.”  The crack in this experiment lies in Chancourtois professional background as a geologist and not as a chemist.   Instead of using chemistry terms for the elements, he instead refers to them in geological terms.  He also introduced his own version of numerology (the alchemy of mathematics, in which certain numbers have their own esoteric significance).  This can be seen as the so-called “crack” because Chancourtois analyzes his observations through the subjective eyes of a geologist, which chemist at that time did not agree with.  Chancourtois work is the first Periodic Table.  Though when his paper was published, the publisher accidentally did not include the diagram of the cylinder causing much confusion when reading the text due to geological terms instead of chemical ones. 

The next scientist to contribute to the organization of the Periodic Table is chemist John Newlands, who propose the theory of periodicity in the properties of elements (Law of Octaves).  He observes that by listing the elements in ascending order of atomic weights, in vertical lines of seven, the properties of the elements along the corresponding horizontal lines are parallel.  Intervals of eight elements lead to a correlative chemical property appearing again.  Newlands applies the theory of the octave of music to the order of the elements, this can also be consider as a “crack” because it’s an individual preference to relate chemical theories to another topic that the individual can relate too, in this case music. 

With a good foundation of summaries of observation, Mendeleev is able to add his own take on the observations and develop a Periodic Table that is considered “less wrong” than his predecessors.  A major contributing factor that aids Mendeleev in his quest for a structure in the elements is the great chemist Cannizzaro.  Scientist at this time was unable to agree upon a common system for measuring the weights of the different elements.  Atoms are too small to be weighed individually so there is a consensus that atoms weights can be determine only on a relative basis.  One school of thought favored the atomic weight method while the other favored the equivalent weight method.  The first international chemistry congress took place in Germany in 1860, where Cannizzaro made a good assumption that the equivalent weight method was based on a ruinous misapprehension. (Strathern p.273)  Hence scientist came to agree upon the atomic weight method due to Cannizzaro persuasive speech.  Here is another “crack” to consider because there are two methods for weighting atom.  Each method does agree upon the theory that the weight of atoms is relative, but with Cannizzaro’s bias for the atomic weight method and his reputation as a charismatic speaker; scientist began to adopt that method over the other one after hearing his speech in Germany. 

Cannizzaro’s speech in favor of atomic weights inspire Mendeleev, “I vividly remember the impression produced by his speeches, which admitted of no compromise and seemed to advocate truth itself… The ideas of Cannizzaro [were] the only ones which could stand criticism and which represented the atom as ‘the smallest portion of an element which enters into a molecule or its compound.’ Only such real atomic weights… could afford a basis for generalization.” (Strathern p.273)  This idea of the real atomic weights as a basis for generalization is the catalysis for the development in the structure of Mendeleev’s Periodic Table.  It was frustrating for him to find a structure that would explain the relationships between the elements. But he persevered believing that there was a key that links the elements together.  He strongly believes that elements could not have random set of properties because in his eyes, “that would be unscientific.” (Strathern p.273)  With a lot of patience, he figured out the relationships between the elements through his favorite card game, solitaire.  This happen when he began to write the names of the elements on blank cards with their atomic weights and chemical properties inscribed on the cards.  The similarity of solitaire to that of the elemental cards is that the cards have to be aligned according to their suit and in descending numerical order.  The suits in the aspects of the elemental cards is their similar properties, and the elements in each group (similar properties) would be align in the sequence of their atomic weights.  There appears to be anomalies to his Periodic Table because there were some gaps.  Mendeleev’s explanation to these gaps was that these elements are not discovered yet, so he predicted the properties and weights of the un-discovered elements.  A few years later, most of the missing elements were discovered and they resembled his prediction.

 I consider Mendeleev’s new summary of observations contains a “crack” in the loopy scientific method.  Mendeleev’s new observations refuted that of Chancourtois cylinder structure, thus the scientific method cycles back to revising the summary of observation.  With this new summary, there exist a “crack.”  In Mendeleev’s case his love for solitaire is the “crack” because it is possible to arrange the elements in another way such as on the basis of the structure of the atom. (Tomkeieff)  The “crack” can also include his favoritism for the atomic weight method since the Periodic Table is base upon that theory.  His summary of observations can be seen as bias from his background identity as someone who loves solitaire and his close-minded belief for the atomic weight method.  One can now sense that the Periodic Table is not pure “truth” but a collection of biased summaries of observations from numerous scientists. 

Moseley in 1911 made the Periodic Table “less wrong” by arranging the elements according to increasing atomic numbers and not by atomic mass (what Mendeleev did). (“History of the Periodic Table”)  This eliminated some inconsistencies that Mendeleev’s Periodic Table contains.  Subsequently, the Periodic Table we have now is base upon Moseley’s theories of atomic number.  This revision demonstrates that the bias of relying on the atomic weight method as a basis for generalization is “more wrong.”

The development of the Periodic Table is to satisfy a need to classify the numerous building blocks of the universe.  Upon closer examination of the story of the Periodic Table, it appears that the method use to develop it follows the loopy scientific method of getting it less wrong.  When another cycle appears due to new summary of observations that refutes the old one, a “crack” is inevitable.  The “crack” contains subjectivity and biasness.  In the case of the Periodic Table, the “crack” is the scientist’s professional background (geologist) and personal preference (favorite card game).  With my summary of evidence, it can be concluded that the Periodic Table is a product made by men through their individualized summary of observations, which contains subjectivity. 

            One can say that the Periodic Table is a suggestion of how to view the relationship between the elements, but it is not the only way to view it.  This is the preferred way to view it because it is the most useful and facile way to understand the chemical properties of elements and their bonding states.  This is similar to Paul’s lecture on why we view the Earth as traveling around the sun rather than vice-versa due to the usefulness of the idea to sailors who do not want to carry numerous books and perform difficult calculations to navigate the sea.  The same is with the Periodic Table.  One does not have to memorize the numerous elements individually to know their bonding states (this would make Organic chemistry harder than what it is now for college students) relative to other elements.  Just by looking at the Periodic Table will provide the information that is needed to predict the bonding states with the organization of similar bonding states in the same column.  The Periodic Table is a good summary of observations scientists have at hand, which makes it a useful theory to view the relationship between elements; never the less it is not the only way to view elements.  Because the Table is useful and there have yet been observations to refute it, most chemistry teachers consider it as a fact, but in actuality it is a product that is “less wrong.”

Sources:

Tomkeieff, Sergei Ivanovich. A New Periodic Table of the Elements Based on The Structure of the Atom. London: Chapman & Hall, 1954.

Atkins, Peter William. The Periodic Kingdom: A Journey into the Land of the Chemical Elements. New York: BasicBooks, c1995

“Science as Story and Story Revision 23 January 2007.” Paul Grobstein. January 23 2007. http://serendip.brynmawr.edu/sci_cult/evolit/s07/23jan07.html [Online: February 16, 2007]

“A Brief History of the Development of Periodic Table.” Western Oregon University. c1997. http://www.wou.edu/las/physci/ch412/perhist.htm [Online: February 16, 2007]

“History of the Periodic Table.” Wikipedia, the free encyclopedia. 27 January 2007. http://en.wikipedia.org/wiki/Periodic_law [Online: February 16, 2007]

Strathern, Paul. Mendeleyev’s Dream: The quest for the Elements. New York: Thomas Dunne Books (imprint of St. Martin’s Press), 2000

Comments

Anne Dalke's picture

periodically

2/19/07

Tu—

I am of course delighted that you decided to take up my challenge of viewing the periodic table as an exemplar/test case for “getting it less wrong”; what I like about this project is the way it brings the particularity of who you are—the only chemistry major in our section—into the conversation that is this course. You have a fine story to tell, about the social construction of this view of the relations among elements, and some of the details—the use of geology, of music, of solitaire—are just delightful to learn about (thanks for the instruction!).

My suggestions have mostly to do with the technicalities of writing a paper. Consider these as you prepare to write the next one:

--you are writing for a world-wide audience, most of whom are NOT taking a course called “The Story of Evolution/The Evolution of Stories.” So don’t assume that your audience knows what you know. Take some time @ the beginning to explain what “the loopy scientific method is,” and how “the crack” opens as a feature, not a bug, in that process. Then set your topic within that framework.

--you are describing a historical process; most of the events you trace happened in the past, and need to be described in the past tense. Some of the events you describe (like the characteristics of various elements) of course still obtain, and should be described in the present tense.

There are a few other spots where you’ll see me adding a point or two, never arguing with you (because, as I said above, I think you have a very compelling story to tell), but just trying to highlight what seem to me to be strong points. And there are a couple of spots where I wanted more information: on p. 4, for instance; why was Cannizzaro biased toward the atomic weight method? Or on p. 5: why did Mendeleev think that randomness was “unscientific”?

Anne

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