Elements of the First Period

Special name Hydrogen Deuterium Tritium HeUom 4 HeUum 31 

Special name Chemical symbol Atomic number Z Hydrogen H 1 Deuterium orD 1 Tritium H orT 1 Helium 4 He 2 Helium 3 Tm 

Elastic compliance 44 Elastic compliance su Elastic compliance s 3 Elastic stiffness cn Elastic stiffness C33 Elastic stiffness C44 Elastic stiffness C12 Elastic stiffness C13 Solubility in water aw At25K. 

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The second reason is due to the volume of the ions. If the central ion is very small, fewer negative ions than the theoretical coordination number can be arranged in such a way that they all touch it. Therefore, since complex formation occurs mainly with small positive ions of high charge, it frequently happens that complexes of elements of the first period have less than the ideal coordination number, while those of the second and third conform to the theoretical value. Thus, instead of the ideal complex ions... 

The spectra of a number of triatomic radicals with 15 valence electrons are now known for elements of the first period they are B02, N3, and NCO. In addition, the isoelectronic ions C02+ and N20+ have been investigated. The spectrum of B02 was observed by Johns41 in the flash photolysis of a mixture of BCI3 and 02, but later was found to be identical to the green bands observed in most flames and arcs containing boron.42 Isotope shifts (B1X-B10) and alternate missing lines in the spectrum immediately identify the carrier as... 

The peculiarities of classical localized coordination bonds (two-electron and two-center [1,4,5]) are displayed most clearly in MCC. Mostly, the elements of the first period of the Periodic Table (C, N, O) participate as electron donors in the formation of such bonds. In complexes of this type, the role of Ji-dative interactions is significant. These interactions are revealed in coordination compounds of ligands containing the elements of the next periods as donor centers (P, As, Sb S, Se, Te Cl, Br, I). We note that the examined complexes are the most successful objects to study the influence of ligand and metal nature on the character of the coordination bond, since, in this case, the factors which could distort this influence (chelate, macrocyclic, and other effects [117,135]) are absent. 

The elements of the first period (see Table 2-3) exhibit the largest chain link number. Within each group, the chain link number decreases with increasing period number. 

This section provides tables of the physical and physicochemical properties of the elements. Emphasis is given to properties of the elements in the condensed state. The tables are structured according to the Periodic Table of the elements. Most of the tables deal with the properties of elements of one particular group (column) of the Periodic Table. Only the elements of the first period (hydrogen and helium), the lanthanides, and the actinides are arranged according to the periods (rows) of the Periodic Table. This synoptic representation is intended to provide an immediate overview of the trends in the data for chemically related elements. 

Table 2.1-6A Elements of the first period (hydrogen and helium). Atomic, ionic, and molecular properties...

The elements of the first period (C, N, O) do not form stable transargononic compounds. This general difference in their chemical properties from their heavier congeners is clearly explained by the nonexistence of 2d orbitals. 

Formation of bridged cations is well documented in the cases when X contains a n system (e.g., X = phenyl). However, if atom X is hydrogen or a hydride of an element of the first period, the bridged stmcture includes one electron in the antibonding orbital. In such cases, the 1,2 shift has not been confirmed yet, with the exception of one observation. ... 

X-ray spectroscopy can also be employed for survey analysis of impurities and has the advantage of being nondestructive. Lower limits of detection are rarely better than 10-100 ppm, unless preconcentration is used, and the elements of the first period cannot be detected at low concentrations. 

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