Periodic system of element

Lowdin, P-O. 1969. Some comments on the periodic system of elements. International Journal of Quantum Chemistry. Symposium 3 331-334. 

The periodic system of elements gets its moniker because it graphs how certain properties of chemicals repeat after regular intervals. In the modem table of 117 elements, each is placed across rows in order of increasing atomic number—the number of protons in the nucleus of one atom of each element. There are seven rows, each... 

Pyykko, P. and Desdaux, J.P. (1979) Relativity and the periodic system of elements. Accounts of Chemical Research, 12, 276-281. 

Fermi, E. (1928). A statistical method for the determination of some atomic properties and the application of this method to the theory of the periodic system of elements, Z. Phys. 48, 73-79. 

For concrete estimates of the parameters of a reaction (3.1) let us turn to diatomic molecules, such as Na2, K2, Te2, which have been studied most in experiments on optical pumping of molecules via depopulation. A number of data characterizing the states and transitions in these objects under conditions typical for such experiments are given in Table 3.7. These parameters are, to a certain extent, characteristic of diatomic molecules in thermal vapors of the first, sixth and seventh group of the periodic system of elements, such as alkali diatomics, S2, Se2,12, etc. These molecules may... 

P. Gombas and T. Szondy, Solutions of the Simplified Self-Consistent Field for All Atoms of the Periodic System of Elements from Z = 2to Z = 92, Adam Hilger, London, UK, 1970. 

Fig. 1.1. Periodic system of elements with stable nuclei or long living unstable nuclei, / + 0. The marks o and distinguish between elements with nuclei difficult accesible (o) to NMR (NQR) experiments, and elements easy accesible ( ) to the NMR(NQR) experiments. This distinction depends from many parameters such as the concentration of the isotope with / + 0, the chemical bond in the lattice, the experience of the experimentator,.

Fig. 21. The periodic system of elements continued up to element 172. The chemical symbols, atomic numbers, and oxidation states are also given. The outer electrons are drawn schematically (56)...

Tn accordance with its electronic configuration and the resulting posi-tion in the periodic system of elements the actinide element americium is the heavy homolog of the rare earth element europium (14) ... 

Lowdin, Per-Olav. 1969. "Some Comments on the Periodic System of Elements." International Journal of Quantum Chemistry S3 331-334. 

It is remarkable that the Dirac theory of the relativistic electron perfectly describes this deviation, and the difference to the reference (the nonrelativistic value) is unusually well defined by the limit of a single parameter (the velocity of light) at infinity. The special difficulty encountered in measuring relativistic effects is that relativistic quantum mechanics is by no means a standard part of a chemist s education, and therefore the theory for interpreting a measurement is often not readily at hand. Still, a great many of the properties of chemical substances and materials, in particular, trends across the periodic system of elements, can be understood in terms of relativistic effects without having to consider the details of the theory. 

Excellent general survey for chemists, physicists specializing in other fields. Partial contents simplest line spectra and elements of atomic theory, building-up principle and periodic system of elements, hyperfine structure of spectral lines, some experiments and applications. Bibliography. 80 figures. Index, xii 257pp. 5 6 x 8- "Paperbound 2.00... 

It was noted before by the same workers that acrolein was formed along with saturated aldehydes in propene oxidation over metal oxides of the Vth and Vlth groups of the Periodic System of Elements (51). The kinetics of acrolein generation from propene over V206 was also studied recently, and the activation energy for this reaction was found to be 12 kcal/mole. 

Elements of the 1st and Ilnd groups of the Periodical System of Elements decrease, and those of the Vlth and VHth groups usually increase the electron work function for metals. The mechanism of variations with adsorption of atoms and molecules of various substances on metal surfaces is due to formation of a double electrical layer... 

Periodic system of elements Structure of molecules (orbital theory)... 

FIGURE 8.1 The periodic system of elements as conceived by the Frankfurt school in the late sixties. The islands of superheavy elements (Z = 114, N = 184,196 and Z = 164, N = 318) are shown as dark hatched areas. 

Mendeleev, D. I. On the Placement of Cerium in the Periodic System of Elements. Bulletin de I Academie imperiale des sciences de St.-Petersbourg 16 (1870/1871) 45. English translation by Trifonov (1970), op. cit, p. 40. (note 36) This paper was completed in November 24, 1870. Originally, Mendeleev had written one big article on the system of the elements but this was afterwards subdivided in Mendeleev (1870/1871) and Mendeleev (1871a). (note 65)... 

As Mendeleev wrote in his article On the Placement of Cerium in the Periodic System of Elements To confirm the above ideas, I undertook the problem of determining the heat capacity of the above-mentioned metals. The experimental results, obtained in the fall of 1870, were confirmed by the investigations of Bunsen and spoke in the advantage of the corrected atomic weights. 

The accommodation of cerium went smoothly as Mendeleev had correctly determined its atomic weight and oxide formulae. According to the dualism of cerium, this rare-earth element exhibited two oxidation states (+III and +IV), making its placement in the fourth group very natural. As Mendeleev reasoned in his article On the Placement of Cerium in the Periodic System of Elements ... 

Fig. 3. Periodic system of elements demonstrating the formation of the simplest binary chemical compounds [2].

Van Spronsen, J.W., 1969, The Periodic System of Elements (Elsevier, Amsterdam). 

The emission of B"-radiation creates a daughter nuclide of the same mass as the parent isotope and located immediately to the right of it in the periodic system of elements, owing to the loss of a negative charge. 

The displacement law provided for harmonious relationship between radioactive families and the periodic system of elements. After several successive alpha and beta decays the originators of the families converted into stable lead giving rise in the process to the natural radioactive elements found between uranium and bismuth in the periodic table. But then each box in the system had to accommodate several radioelements. They had identical nuclear charges but different masses, that is, they looked as varieties of a given element with identical chemical properties but different masses and radioactive characteristics. In December 1913 Soddy suggested the name isotopes for such varieties of elements (from the Greek for the common place ) because they occupy the same box in the periodic system. 

Now let us turn back to the last decades of the 19th century. When Mendeleev developed the periodic system of elements it contained many empty slots corresponding to unknown elements between bismuth and uranium. These empty slots were rapidly filled after the discovery of radioactivity. Polonium, radium, radon, actinium, and finally protactinium took their places between uranium and thorium. Only eka-iodine and eka-cesium were late. This fact, however, did not particularly trouble scientists. These unknown elements had to be radioactive since there was not even a hint of doubt that radioactivity was the common feature of elements heavier than bismuth. Therefore, sooner or later radiometric methods would demonstrate the existence of elements 85 and 87. 

Austrian scientists discovered three elements tellurium (1782), praseodymium (1885), and neodymium (1885). Danish scientists discovered aluminium (1825) and hafnium (1923) one element (ruthenium) was discovered in Russia in 18. But Russian scientists extracted many newly discovered elements from natural minerals and studied their properties (platinum metals, chromium, strontium). Though for a variety of reasons Russian chemists did not discover many new elements one should not forget that the periodic system of elements was developed by the great Russian chemist D. Mendeleev and this task was much more difficult than to discover a few new elements. 

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