Properties of the elements

The atomic properties of the Group 13 elements (including boron) are compared in Table 7.4. All have odd atomic numbers and correspondingly few stable isotopes. The varying precision of 

Boron is a covalently bonded, refractory, non-metallic insulator of great hardness and is thus not directly comparable in its physical properties with Al, Ga, In and Tl, which are all low-melting, rather soft metals having a very low electrical 

Up to 5% Mg is added to most commercial Al to improve its mechanical properties, weldability and resistance to corrosion. 

For further details see Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn., 1995, Vol, 15, pp, 622-74. 

Metallic Sr and Ba are best prepared by high-temperature reduction of their oxides with Al in an evacuated retort or by small-scale electrolysis of fused chloride baths. They have limited use as getters, and a Ni-Ba alloy is used for sparkplug wire because of its high emissivity. Annual production of Ba metal is about 20-30 tonnes worldwide and the 1991 price about 80-140/kg depending on quality. 

Beryllium, Magnesium, Calcium, Strontium, Barium and Radium 

Be is much less than that of its congeners, again indicating its lower electropositivity. By contrast, Ca, Sr, Ba and Ra have reduction potentials which are almost identical with those of the heavier alkali metals Mg occupies an intermediate position. 

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Among the non-metals, nitrogen and chlorine, for example, are gases, but phosphorus, which resembles nitrogen chemically, is a solid, as is iodine which chemically resembles chlorine. Clearly we have to consider the physical and chemical properties of the elements and their compounds if we are to establish a meaningful classification. 

In any group of the periodic table we have already noted that the number of electrons in the outermost shell is the same for each element and the ionisation energy falls as the group is descended. This immediately predicts two likely properties of the elements in a group (a) their general similarity and (b) the trend towards metallic behaviour as the group is descended. We shall see that these predicted properties are borne out when we study the individual groups. 

The chemical properties of the elements in a given group of the Periodic Table change with increasing atomic number. 

Some of the more important physical properties of the elements are given in Table 10.1. 

The trends in chemical and physical properties of the elements described beautifully in the periodic table and the ability of early spectroscopists to fit atomic line spectra by simple mathematical formulas and to interpret atomic electronic states in terms of empirical quantum numbers provide compelling evidence that some relatively simple framework must exist for understanding the electronic structures of all atoms. The great predictive power of the concept of atomic valence further suggests that molecular electronic structure should be understandable in terms of those of the constituent atoms. 

The element was first prepared by Klemm and bonner in 1937 by reducing ytterbium trichloride with potassium. Their metal was mixed, however, with KCl. Daane, Dennison, and Spedding prepared a much purer from in 1953 from which the chemical and physical properties of the element could be determined. 

TABLE 4.1 Electronic Configuration and Properties of the Elements Continued)... 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

Chemical ingenuity in using the properties of the elements and their compounds has allowed analyses to be carried out by processes analogous to the generation of hydrides. Osmium tetroxide is very volatile and can be formed easily by oxidation of osmium compounds. Some metals form volatile acetylacetonates (acac), such as iron, zinc, cobalt, chromium, and manganese (Figure 15.4). Iodides can be oxidized easily to iodine (another volatile element in itself), and carbonates or bicarbonates can be examined as COj after reaction with acid. 

T. D. Parr, Phosphorus—Properties of the Element and S ome of its Compounds, Chemical Engineering Report No. 8, Tennessee Valley Authority, Part XI, U.S. Government Printing Office, Washington, D.C., 1950. 

T. D. Farr, Phosphorus, Properties of the Element and Some of Its Compounds, in Chemical Engineering Report, No. 8, Tennessee Valley Authority, Wilson Dam, Ala., 1950, pp. 39 and 58. 

Barium is a member of the aLkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely aUied series in which the chemical and physical properties of the elements and thek compounds vary systematically with increa sing size, the ionic and electropositive nature being greatest for barium (see Calcium AND CALCIUM ALLOYS Calcium compounds Strontium and STRONTIUM compounds). As size increases, hydration tendencies of the crystalline salts increase solubiUties of sulfates, nitrates, chlorides, etc, decrease (except duorides) solubiUties of haUdes in ethanol decrease thermal stabiUties of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

TABLE Physical Properties of the Elements and Inorganic Compounds ... 

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