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Atomic weight INDEX

In 1917 Harkins found that on the average elements of even atomic number (Z) are about 70 times as abundant in meteorites as those of odd Z he further noted that the first seven elements in the order of their abundance are all even-numbered and make up almost 99% of the material in meteorites. [28] Four years later he elaborated his assumption that the relative abundances of the atomic species of low atomic weight may be used as an index... of their relative stability. He now suggested several more rules, including that atoms with even A (mass number) and an odd number of electrons are extremely rare. [29] These rules were claimed to be valid for isotopes, and not merely elements. In 1931, after more data on the distribution of isotopes had been collected, he reported that even-A nuclei were much more frequent than odd-A nuclei. [30]... [Pg.165]

Analysis. There are five important methods for measuring the ratios of isotopes, making use respectively of—the spectrograph, the mass spectrograph, density measurements, atomic weight measurements and refractive index measurements. Any of these methods must be pushed to the present limits of accuracy or beyond in order to meet the requirements for tracer experiments. If, for example, an increase in concentration of C13 is effected from 1 per cent to 1.1 per cent and an accuracy of five per cent in the increase is required the determination must be accurate to one part in 20,000. [Pg.252]

Table of atomic weights 1454 Index 1455 Reference data 1511 Abbreviations 1513... [Pg.1497]

If the array is one-dimensional, only one pointer argument need be specified. Example If the reference C 2 C 102 contains the atomic weights of the elements, arranged in order of atomic niunber, then =INDEX( C 2 C 102,51) returns the atomic weight of element number 51. [Pg.403]

OD (zero-dimensional) descriptors such as molecular weight and atomic composition indexes. [Pg.765]

At.-Gew. Atomgewicht, atomic weight R.I.-Bzfg. Ring Index-Bezifferung, ring in-... [Pg.516]

The moment index based on the atomic weights m was called normalized molecular moment, M , and defined as [King and Molnar, 1997]... [Pg.554]

Chemical adjacency matrices based on relative atomic masses were used to calculate the —> atomic molecular connectivity index, Zagreb topochemical indices, and the superadjacency topochemical index, all defined in terms of the Madan chemical degree 5 ", which is the row sum of the atomic weight-weighted adjacency matrix. [Pg.896]

The row sum of this matrix is a local vertex invariant called chemical distance degree the maximum entry in each row is called chemical atom eccentricity, which is the maximum distance weighted by relative atomic weights from each atom. The chemical atom eccentricity is used in the calculation of the —> superadjacency topochemical index, while the chemical distance degree in the calculation of the Wiener topochemical index. [Pg.905]

The Wiener topochemical index was proposed as a modification of the —> Wiener index to account for heteroatoms. It is calculated as the half sum of the elements of the atomic weight-... [Pg.905]

Indium is a ductile, shiny silver-white metal that may also exist in a black powder form. Indium has an atomic weight of 114.82, an atomic number of 49, and a specific gravity of 7.31 g cm It has a boiling point of 2080 °C, a melting point of 1566°C, and is insoluble in water. The major oxidation states for indium are +1, +2 and +3 valences (Merck Index Online 2002). In aqueous solution, only In(III) is stable, but solid-state compounds with +1 and +2 valences have been isolated (Cotton and Wilkinson 1972). [Pg.801]

Pi, to O Such relationships are called additivity laws, and are fundamental in many areas of physical chemistry. An additive property is one whose value is determined by adding up the contributions from smaller units. An almost trivial example (though it wasn t a century and a half ago) is the relationship between the molecular weight of a compound and the atomic weights of its constituent atoms. Molecular weights and molecular volumes are additive melting points or refractive indexes are not. [Pg.234]

The handbook terminates with an Author Index covering all the names appearing in the individual reference lists of the chapters, followed by a comprehensive Subject Index, a List of the Elements including their atomic weight, and a Periodic Table to further facilitate orientation. [Pg.9]

In Eq. (7.1), states A and B are the two electronic states ground and excited states associated with the conical intersection, is the yth mass-weighted Cartesian coordinate of the t th atom, the index i labels the N atoms and y the Cartesians components, x, y, and z. These quantities are in principle obtainable only from a theoretical calculation. Nevertheless, as we shall discuss subsequently, they have a simple interpretation and one can often make a reasonable guess as to the nature of these two vectors using qualitative valence bond theory. [Pg.188]


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