|The development of the Periodic Table (pre-16)|
Could the original formulation of the Periodic Table be regarded as British? Just four years before Mendeleev announced his Periodic Table, John Alexander Reina Newlands wrote in Chemical News
Surely this was a prediction of patterns in the properties of the elements and described a Periodic Table?
Newlands thought that patterns were connected with the relative weights of atoms (we would now call them relative atomic masses – they were then called atomic weights) of different elements. Fortunately, in 1860 there had been a conference in Karlsruhe (Germany) which had made a more accurate list of these atomic weights than had previously been available. Not only had some values been slightly wrong through inaccurate measurements but some were half or a third of the correct value through false reasoning. See Problems with relative atomic masses.
One difficulty was that only about 60 elements were known then (there are over 100 now), although fortunately most of the undiscovered ones were of higher relative atomic mass. Newlands listed those known in order of their atomic weight putting their position in this sequence alongside the symbol. He did not give a name to this position number. A copy of his table is shown below using the symbols Newlands used.
The pattern was perfect up to calcium then became less convincing as some metals appeared unlike the non-metals to their left. However a further seven elements later there was a greater similarity. Then Newlands was forced to sometimes put two elements in the same box so that after this similar elements would be in the same horizontal line. Di stood for didymium, which we now know is not an element at all but a mixture of two elements.
Note that Newlands did not always stick to a strict increase in number. He exchanged the positions of Zn and Y, presumably because he realised that Y resembled Bo (modern symbol B). The modern Periodic Table does not always show an increase in relative atomic masses for successive elements but it is a less common occurrence than in Newlands’ table.
On 1st March 1865, he described his ideas at a lecture at the Chemical Society (a forerunner of the Royal Society of Chemistry). The lack of spaces for undiscovered elements and the placing of two elements in one box were justifiably criticised but an unfair suggestion from Professor Foster was that he might have equally well listed the elements alphabetically. Foster was on the Publication Committee which refused to publish his paper, supposedly because it was of a purely theoretical nature. Humiliated, Newlands went back to his work as chief chemist at a sugar factory.
Four years later Mendeleev, unaware of Newlands' ideas, formulated an improved Periodic Table which gained acceptance, particularly because he left spaces for undiscovered elements, some of which were soon found with properties he predicted. As the Periodic Table became accepted, Newlands, understandably, claimed its first publication. However the Chemical Society did not back his claims. Indeed the final years of his working life were spent running a family chemical business with his brother.
The Chemical Society made some amends for discrediting him by asking him in 1884 to give a lecture on the Periodic Law. However its full recognition of his discovery waited until 1998, the centenary of his death, when the Royal Society of Chemistry oversaw the placing of a blue commemorative plaque on the wall of his birthplace. Note its inscription.
Reproduced courtesy of Gordon Woods