Atomic volume curve, periodicity

L. Meyer drew up an atomic volume curve and a periodic table, but this laner was not published until 1895. 

Quantum mechanics has shown that periodicity is conditioned by the repetition of the configurations of outer electrons and it is natural that only those properties which are concerned with the structure of the outer electrons of the atoms should reveal periodicity. Thus it is found that ionization potentials, ionic dimensions, polarisation etc when considered as a function of atomic number give a curve similar to the atomic volume curve. Other... 

In the same paper he published the first version of his Periodic Table. One year later, Lothar Meyer supported Mendeleev s conclusions in a paper which had an essentially identical table. Meyer s paper contains the famous atomic volume curve showing maxima and minima as the atomic weight increased. 

Atomic volume, defined as the volume in cm, occupied by one gram atomic weight of an element, was shown by Lothar Meyer in 1869 to be a periodic function of the atomic weight (more correctly the atomic numbers). With reference to the atomic volume curve shown below, rationalize the following features on the basis of your knowledge of the electronic structure of atoms. 

It is thus significant that on November 30,1882, Britain s premier scientific society, the Royal Society, awarded the Davy Medal jointly to Mendeleev and Lothar Meyer, not wishing to indicate sole primacy of discovery of the periodic law. The president (mathematician William Spottiswoode) spoke of how the labors of Mendeleev and Lothar Meyer had extended our knowledge of the relations between the atomic weights of the elements and their respective chemical and physical properties, and atomic volume curves (Fig. 4.3). ... 

Mendeleev s reluctance toward reduction was not widely shared. One of the codiscoverers of the periodic system, the German Lothar Meyer, accepted the possibility of primary matter and supported Prouf s hypothesis. He was also happy to draw curves through numerical data, including his famous plot of atomic volumes that showed such remarkable periodicity that it helped in the acceptance of the periodic system. Nonetheless, prior to Thomson s discovery of the electron, no accepted model of atomic substructure existed to explain the periodic system, and the matter was still very much in dispute. 

Figure 2. Dimitri Mendeleev s discovery of the periodic system in 1869 was quickly followed by controversy over how it should be used, Mendeleev resisted reduction or explanation of the system in terms of atomic structure, and was specifically opposed to attempts to draw curves through points representing numerical data Lothar Meyer, who contributed to the discovery of the periodic system, was not so averse to reduction, however. One of his graphs, shown here in an 1870 publication, plotted atomic volume and was instrumental in the acceptance of the periodic system.

Lothar Meyer s Periodic Curve of Atomic Volumes,... 

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 ... 

FIG. 5-1. Curve of gram-atomic volume (the volume containing 1 gram-atom) of the elements as function of atomic number, illustrating periodicity of properties. 

From the dependence of atomic polarizability by the cubic atomic radii rises immediately the correspondence with the atomic volume also. Therefore, atomic polarizability states as a fully atomic related property and have to closely follow the periodicity of atomic volumes, the Lothar Meyer s periodic curve. 

Meyer plots the atomic volume (atomic weight divided by density) of each element against its atomic weight and shows that elements whose chemical properties are similar appear in similar positions on the waves of the curve. Russian chemist Dmitry Mendeleyev publishes the first periodic table for chemical elements. He writes, The properties of the elements are in periodic dependence upon their atomic weight. His table shows how the elements are related to each other and how increasing atomic weight affects their chemical reactivities. Gaps in the table indicate elements yet to be discovered and predict their properties. Mendeleyev coins the term transition element British chemist Sir William Perkin develops synthetic alizarin for manufacture from the madder plant. 

It has been a constant pursuit of chemists to classify the elements in terms of such an affinity factor, in order to predict details of their interaction. The discovery of the periodic table provided the first clue towards identification of such a chemicalbonding parameter, which later became known as electronegativity. On plotting Lothar-Meyer atomic volumes as a function of atomic number, the elements are divided into two kinds, according to the local slope of the connecting curve [35]. This observation led to the classification into electropositive and electronegative elements. 

A second powerful use of diffraction is in atomic-scale structure determination, which is especially well known for LEED [127, 163-166]. There the experimental and calculated intensity-voltage (I-V) curves are compared for various surface structures, taking multiple scattering of electrons into account (see Chapter 3.2.1 in Volume 1). However, there is a complication in performing the calculations for QCs because periodic boundary conditions cannot be applied (the same problem noted earlier for DFT). 

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