Meyer, Lothar table

For nearly three centuries, a new element has been discovered every two-and-one-half years, on average. Undoubtedly, more will be found. Although their names and their discoveries will fikely involve controversies, their place at the table is already set. see also Alchemy Avogadro, Amedeo Bec-QUEREL, Antoine-Henri Bohr, Niels Cannizzaro, Stanislao Dalton, John Lavoisier, TVntoine Mendeleev, Dimitri Meyer, Lothar Pauli, Wolfgang Ramsay, William Rontgen, Wilhelm Rutherford, Ernest Seaborg, Glenn Theodore Thomson, Joseph John. 

The first striking fact here is that medal was awarded not to Mendeleev alone, but rather jointly to him and the German chemist Lothar Meyer. This already poses a problem for the predictivist thesis. Although Lothar Meyer s scheme was, as he himself pointed out, essentially identical to Mendeleev s, Meyer failed to draw attention to the existence of gaps in the periodicities displayed by the table and hence failed to predict new elements. Only Mendeleev explicitly derived the consequence that the scheme must be regarded as containing gaps and therefore only Mendeleev explicitly predicted the new elements.11... 

The closet precursor to Mendeleev s table in both chronological and philosophical toms was developed by Julius Lothar Meyer, a German chemist, in 1864. Although Meyer stressed physical rather than chemical properties, his table bears remarkable similarity to the one that Mendeleev would develop five years later. For a number of reasons, Meyer s prominence in tlte history books never matched Mendeleev s. There was an untimely delay in the publication of his most elaborate periodic table, and, perliaps more important, Meyer—unlike Mendeleev—hesitated to make predictions about unknown elements. 

Our modem periodic table was developed independently in the late 1860s by Dimitri Mendeleev (Russian) and Julius Lothar Meyer (German). At that time, about 60 elements had been discovered, but nothing was known about atomic stracture. Lothar Meyer and Mendeleev had to work with elemental molar masses and other known elemental properties. 

Mendeleev, a chemist, examined the relative numbers of the atoms of different elements that combine in chemical compounds. In MgCl2, for example, each magnesium atom combines with two chlorine atoms. When he matched combining ability against molar mass, Mendeleev found the same sort of pattern as Lothar Meyer, with Li, Na, K, Rb, and Cs all combining 1 1 with Cl. Thus, each scientist was led to propose a table in which elements are arranged in rows of increasing mass, with breaks so that these five elements fall in the same column. 

Mendeleev was bolder in his interpretation than Lothar Meyer, and for this reason we honor him as the primary discoverer of the modem periodic table. A few elements did not fit the pattern of variation in combining numbers with molar mass. Mendeleev proposed that these irregularities meant that the element s molar mass had been measured incorrectly. For example, Mendeleev predicted that the correct molar mass of indium is 113 g /mol, not 75 g /mol, the value assigned at that time on the assumption that the formula for indium oxide is InO. Later experiments showed that the correct formula is L12 O3, and indium s tme molar mass is 114.8 g/mol. 

New scientific methods (e.g. electrolysis) allowed the veteran elements to be joined stepwise by more and more unknown and unexpected substances that fulfilled the criteria for an element. In 1869, after many attempts to bring order into the growing chaos, Dimitri Mendeleev revealed a daring concept with his Periodic Table and its predictions. Each of the then known elements was assigned a place. The gaps represented elements that were not yet known. The discoveries of such elements proved that there was an order and system to the elements. This order explained much that was previously puzzling, for instance, the different atomic radii observed that same year by Julius Lothar Meyer, which seemed to follow a periodic trend. 

Very soon afterwards, however, two scientists independently produced the definitive statement on the classification of the elements - Julius Lothar Meyer (1830-95) in Germany and Dmitri Ivanovich Mendeleev (1834-1907) (also spelled Mendeleeff or Mendelejeff) in Russia. It is the latter who is now credited with the construction of the first periodic table. At the age of 35, Mendeleev was Professor of Chemistry at the University of St Petersberg, when he published his first paper (1869) on the periodic system. He was apparently unaware of the work of Newlands or Lothar Meyer, but came to the same conclusions, and was also prepared to go further, and predict that certain elements must remain to be discovered because of discrepancies in his table. Amongst other things, he concluded the following ... 

A remarkable property of the atomic weights was discovered, in the sixties, independently by Lothar Meyer and Mendeleeff. They found that the elements could be arranged in rows in the order of their atomic weights so that similar elements would be found in the same columns. A modernised form of the Periodic Table will be found on pp. 106, 107. It will be noticed, for example, that the "alkali" metals, Lithium, Sodium, Rubidium and Caesium, which... 

Another very early classification of the elements was made by Lewis Reeve Gibbes, professor of chemistry at the College of Charleston, South Carolina, who worked out the first version of his Synoptical Table of the Chemical Elements between 1870 and 1874, and in 1875 discussed an improved form of it before the Elliott Society of Charleston. The hardships of the reconstruction period, however, made prompt publication impossible. When the paper was finally published in 1886, it attracted little attention because the periodic tables of Lothar Meyer and Mendeleev were already well known (39). 

Two chemists in attendance at the Karlsruhe were Julius Lothar Meyer (1830-1895) and Dmitri Mendeleev (1834-1907). These two independently developed the periodic law and constructed their own versions of the periodic table. Meyer based his table primarily on the physical properties of the elements. Meyer plotted atomic volume against the atomic mass and noticed the periodicity in volumes of the elements. Other physical properties also showed periodic trends. Figure 6.2 shows how the melting point of the first fifty-five elements rises and falls in a roughly periodic fashion as atomic number increases. Based on his analysis, Meyer published his periodic table in 1870. 

Figure 8. Old Forest Academy building in Eberswalde, Germany, where Julius Lothar Meyer drafted his first comprehensive periodic table. (Photo Copyright J.

The atomic volumes ol the four elements lie on an ascending branch of Lothar Meyer s periodic curve,1 the positions being in accordance with the non-mctallic nature, low fusibility and ready volatility of the elements. The gradation in physical properties is indicated in i he following table ... 

Mendeleyev s periodic table became the one of the most famous diagrams in the history of science—but why After all, many other scientists had come up with their own ways of organizing the elements. In fact, a German chemist named Lothar Meyer created a periodic table just a few months before Mendeleyev wrote his table. What was it about Mendeleyevs table that made it so special ... 

Many atomic masses were determined as a direct result of Dalton s postulates and the work that they stimulated, and scientists attempted to relate the atomic masses of the elements to the elements properties. This work culminated in the development of the periodic table by Dmitri Mendeleyev (1834-1907) (Figure 3.8) and independently by Lothar Meyer (1830-1895). Because Mendeleyev did more with his periodic table, he is often given sole credit for its development. 

It can be mentioned here that another pioneer of the periodic system, the German Julius Lothar Meyer (1830-1895) did not list the rare earths in his first periodic table, because he was not convinced that the rare earths were genuine elements (van Spronsen, 1969). He also foimd that their atomic weights had not been determined with sufficient accuracy. 

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