Element gaseous

A gaseous element, oxygen forms 21 % of the atmosphere by volume and is obtained by liquefaction and fractional distillation. The atmosphere of Mars contains about 0.15% oxygen. The element and its compounds make up 49.2%, by weight, of the earth s crust. About two thirds of the human body and nine tenths of water is oxygen. 

Gr. neos, new) Discovered by Ramsay and Travers in 1898. Neon is a rare gaseous element present in the atmosphere to the extent of 1 part in 65,000 of air. It is obtained by liquefaction of air and separated from the other gases by fractional dishhation. 

Radon is the heaviest of the hehum-group elements and the heaviest of the normal gaseous elements. It is strongly radioactive. The most common isotope, Rn, has a half-life of 3.825 days (49). Radon s scarcity and radioactivity have severely limited the examination of its physical properties, and the values given ki Table 3 are much more uncertain than are the values Hsted for the other elements. 

The superb reduciag power of potassium metal is clearly demoastrated by its facile displacemeat of protoas ia the weakly acidic hydrocarboas (qv), amines, and alcohols (Table 2). Reactions with inorganics and gaseous elements are summarized ia Table 3. 

W. Ramsay (University College, London) discovery of the inert gaseous elements in air and their place in the periodic system. 

Very light gases, notably hydrogen and helium, tend to escape from the earths atmosphere. The hydrogen you generate in the laboratory today is well on its way into outer space tomorrow. A similar situation holds with helium, which is found in very limited quantities mixed with natural gas in wells below the earths surface. If helium is allowed to escape, it is gone forevei and our supply of this very usefiil gaseous element is depleted. 

Aris obtained from the direct combination of the gaseous elements under the standard state condition. 

Abstract Molecular spectroscopy is one of the most important means to characterize the various species in solid, hquid and gaseous elemental sulfur. In this chapter the vibrational, UV-Vis and mass spectra of sulfur molecules with between 2 and 20 atoms are critically reviewed together with the spectra of liquid sulfur and of solid allotropes including polymeric and high-pressure phases. In particular, low temperature Raman spectroscopy is a suitable technique to identify single species in mixtures. In mass spectra cluster cations with up to 56 atoms have been observed but fragmentation processes cause serious difficulties. The UV-Vis spectra of S4 are reassigned. The modern XANES spectroscopy has just started to be applied to sulfur allotropes and other sulfur compounds. 

Room-temperature fluorescence (RTF) has been used to determine the emission characteristics of a wide variety of materials relative to the wavelengths of several Fraunhofer lines. Fraunhofer lines are bands of reduced intensity in the solar spectrum caused by the selective absorption of light by gaseous elements in the solar atmosphere. RTF studies have recently included the search for the causes of the luminescence of materials and a compilation of information that will lead to "luminescence signatures" for these materials. For this purpose, excitation-emission matrix (EEM) data are now being collected. 

Determination of Gaseous Elements in Metals. Edited by Lynn L. Lewis, Laben M. Melnick, and Ben D. Holt... 

Oxygen A gaseous element essential to human life comprises about 20% of the air... 

Schematic representation of an apparatus that measures the absorption spectrum of a gaseous element. The gas in the tube absorbs light at specific wavelengths, called lines, so the intensity of transmitted light is low at these particular wavelengths.

A multielectron atom can lose more than one electron, but ionization becomes more difficult as cationic charge increases. The first three ionization energies for a magnesium atom in the gas phase provide an illustration. (Ionization energies are measured on gaseous elements to ensure that the atoms are isolated from one another.)... 

Forces of attraction between molecules are responsible for the existence of liquids and solids. In the absence of these intermolecular forces, all molecules would move independently, and all substances would be gases. The natural phases of the elements indicate the importance of intermolecular forces. At room temperature and pressure, only 11 elements are gases. Mercuiy and bromine are liquids, and all the rest of the elements are solids. For all but the 11 gaseous elements, intermolecular forces are too large to ignore under normal conditions. 

C16-0118. A chemist claims to have discovered a new gaseous element, effluvium (Ef), which reacts with... 

Weiss-Penzias P, Jaffe DA, McClintick A, Prestbo EM, Landis MS. 2003. Gaseous elemental mercury in the marine boundary layer evidence for rapid removal in anthropogenic pollution. Environ Sci Technol 37 3755-3763. 

In the case of liquid and gaseous elements boiling point (italics)... 

Nitrogen. Nitrogen, a colorless, odorless, and tasteless gaseous element, is the main component of the atmosphere, which makes up about 78% of its volume since it is also an important constituent of living organisms,... 

The gaseous elements hydrogen, nitrogen, and fluorine exist as diatomic molecules when they are not combined with other elements. Draw an electron dot structure for each molecule. 

If the KrF bond enthalpy is 50 kj mol-1 and the F—F bond enthalpy is 159 kj mol-1, what would be the heat of formation of gaseous KrF2 from the gaseous elements ... 

The lattice enthalpy, Aiatt//m, is the molar enthalpy change accompanying the formation of a gas of ions from the solid. Since the reaction involves lattice disruption the lattice enthalpy is always large and positive. Aatom//m and Adiss//m are the enthalpies of atomization (or sublimation) of the solid, M(s), and the enthalpy of dissociation (or atomization) of the gaseous element, X2(g). The enthalpy of ionization is termed electron gain enthalpy, Aeg//m, for the anion and ionization enthalpy, Ajon//m, for the cation. 

Both models apply the same chemical scheme of mercury transformations. It is assumed that mercury occurs in the atmosphere in two gaseous forms—gaseous elemental HgO, gaseous oxidized Hg(II) particulate oxidized Hgpart, and four aqueous forms—elemental dissolved HgO dis, mercury ion Hg2+, sulphite complex Hg(S03)2, and aggregate chloride complexes HgnClm. Physical and chemical transformations include dissolution of HgO in cloud droplets, gas-phase and aqueous-phase oxidation by ozone and chlorine, aqueous-phase formation of chloride complexes, reactions of Hg2+ reduction through the decomposition of sulphite complex, and adsorption by soot particles in droplet water. 

To remove any possible confusion, we further refine the definition of ionization energy, and say that 7 is the minimum energy required to ionize 1 mol of a gaseous element. The ionization energy 7 relates to process (2) process (1) is additional. 

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