Periodic Table History

UPDATE: June 2011 – debate is raging as to what format the Periodic Table should ultimately take and indeed whether there is an ultimate, fundamental structure or whether it is merely a convenience. Check out the periodic table debate here.

Periodic Table History

Here’s a book no chemist, or indeed no scientist, should miss – The Periodic Table: Its Story and Its Significance, by UCLA chemical philosopher Eric Scerri. Older readers will recall my Alchemist interview with Eric Scerri.

The book has already had some excellent advance reviews, one in particular from my good friend John Emsley, of Cambridge U says: “Written to a high standard of scholarship, ‘The Periodic Table’ is the only book of its kind currently on the market, giving both an historical and philosophical perspective to the development of this key to the elements. The philosophical discussion Scerri weaves through its pages is rarely found in chemistry books, giving it a special quality that will appeal to the scientific community at large. In years to come it will be seen as essential reading for all who aspire to lecture and write on the subject.”

Peter Atkins, who I have never met admittedly, had this to say: “Few concepts are more important in chemistry than the periodic table, and Eric Scerri’s book offers a wonderfully thorough, lucid, and provocative introduction for both chemists and the scientifically literate to this major cultural contribution. Anyone interested in the foundations of chemistry will take delight, inspiration, and information from this highly approachable book.”

You can place an advance order via amazon, the book hits the shelves September 15 at $35 hardcover.

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7 thoughts on “Periodic Table History

  1. Well, what I’d like is for someone to summarise the whole comment thread on this post for me in 500-600 words or fewer and then post it to sibling site http://www.sciscoop.com which takes guest posts…unfortunately, I don’t have the clarity of thought to pull all those threads together sensibly.

  2. Not sure what you mean Roy…I’m sure there will be more follow-up comments. I have no plans to write a new post myself on this subject, it’s far too controversial ;-)

  3. In 1862, a year before John Alexander Reina Newlands published his classification of the elements, de Chancourtois created a fully-functioning and unique system of organizing the chemical elements. His proposed classification of elements was based on the newest values of atomic weights obtained by Stanislao Cannizzaro in 1858. De Chancourtois devised a spiral graph that was arranged on a cylinder, which he called vis tellurique, or telluric helix because tellurium was the element in the middle of the graph. De Chancourtois ordered the elements by increasing atomic weight and with similar elements lined up vertically.

    De Chancourtois plotted the atomic weights on the surface of the cylinder with a circumference of 16 units, the approximate atomic weight of oxygen, the first Periodic Table. The resulting helical curve brought similar elements onto corresponding points above or below one another (as on the modern periodic tables) on the cylinder. He was the first scientist to see the periodicity of elements when they were arranged in order of their atomic weights. He saw that the similar elements occurred at regular atomic weight intervals. Publication of his work, difficult to understand without even the diagram of the helix included, attracted little attention from chemists around the world. It was not until 1869 that Dmitri Mendeleev’s periodic table attracted attention and gained widespread scientific acceptance.

    Before this, however, the quest for a systematic arrangement of the elements started with the discovery of individual elements. By 1860 about 60 elements were known and a method was needed for organization. The development of periodic relationships was advanced by German chemist Johann Dobereiner who grouped elements based on similarities; that calcium strontium and barium possess similar chemical properties, that the atomic weight of strontium fell midway between the weights of calcium and barium, and that there was the same pattern for the alkali metal triad (Li/Na/K) and the halogen triad (Cl/Br/I).

    In 1829 Dobereiner proposed the Law of Triads, in which the middle element in a vertical triad had an atomic weight that was the average of the other two members. Soon other scientists found chemical relationships which extended beyond triads. Fluorine was added to Cl/Br/I group; sulfur, oxygen, selenium and tellurium were grouped into a family; nitrogen, phosphorus, arsenic, antimony, and bismuth were classified as another group. Following de Chancourtois’ “telluric screw”, English chemist John Newlands, having arranged the 62 known elements in order of increasing atomic weights, noted that after an interval of eight elements, similar physical/chemical properties reappeared. In 1863 he wrote a paper proposing the Law of Octaves proclaiming this. Because the use of a musical analogy in a chemical theory sounded like a regression to Pythagorean mysticism, the theory was ridiculed. It was not until Mendeléev published his periodic table that Newlands’ law was shown to have a great deal of truth to it.

    In the Journal of the Chemical Society (1889), Mendeleev quoted the premise of his 1869 exposure of his periodic table, saying;” Without entering into details, I will give the conclusions I then arrived at, in the very words I used:– “1. The elements, if arranged according to their atomic weights, exhibit an evident periodicity of properties.” He then recognized the additions and advances that had occurred in the interim.

    When he originally organized the table into rows, a pattern became apparent – but only if he left blanks in the table. Mendeleev was bold enough to suggest that new elements not yet discovered would be found to fill the blank places, going so far as to predict the properties of the missing elements. Although many scientists greeted Mendeleev’s first table with skepticism, its predictive value soon became clear. The discovery of gallium in 1875, of scandium in 1879, and of germanium in 1886 supported the idea underlying Mendeleev’s table. Each of the new elements displayed properties that accorded with those Mendeleev had predicted, based on conclusions he shared with de Chancourtois and Newlands; that elements in the same column have similar chemical properties.
    A visual difference between Mendeleev’s layout and that of modern tables, is his initial arrangement the element groups horizontally, so that periods of elements appear in vertical columns instead of the current horizontal rows, and more importantly, the elements are now arranged by number rather than by weight.

    In 1871 Mendeleev revised the 17-group table with eight vertical column groups (the eighth group consisted of what were then considered transition elements). This table exhibited similarities not only in small units such as the triads, but showed similarities in an entire network of vertical, horizontal, and diagonal relationships. The table contained gaps, but Mendeleev predicted the discovery of new elements to fill them.

    Lord Rayleigh and William Ramsey greatly enhanced the periodic table by discovering the “inert gases.” In 1895 Rayleigh reported the discovery of a new gaseous element named argon, and did not fit any of the known periodic groups. Ramsey followed by discovering the remainder of the inert gases and positioning them in the periodic table. This is the 8th column, now called the noble gases, and the transition elements moved elsewhere. So by 1900, the periodic table was taking a familiar shape with elements arranged by atomic weight.

    Soon after Rutherford’s landmark experiment of discovering the nucleus in 1911, Henry Moseley subjected known elements to X-rays. He was able to derive the relationship between X-ray frequency and number of protons. When Moseley arranged the elements according to increasing atomic numbers and not atomic masses, some of the inconsistencies associated with Mendeleev’s table were eliminated. The modern periodic table is based on atomic numbers, and divided into periods, columns, groups, and blocks. There is no universal agreement upon all of these, least of all the blocks, which appears to be strong on dogma and weak on science.

    The last major changes to the periodic table resulted from Glenn Seaborg’s work in the middle of the 20th century, moving the Rare earths to below the rest of the table. Then, 20 years later, Roy Alexander found a way that was agreeable to Dr. Seaborg ( http://www.allperiodictables.com/aptpages/gridlink/grid17_seaborg.htm ) to move them back to their correct position by employing Alexander’s patented 3D form of the table, the Alexander Arrangement of Elements,.

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