Substance elementary

Thin films of metals, alloys and compounds of a few micrometres diickness, which play an important part in microelectronics, can be prepared by die condensation of atomic species on an inert substrate from a gaseous phase. The source of die atoms is, in die simplest circumstances, a sample of die collision-free evaporated beam originating from an elemental substance, or a number of elementary substances, which is formed in vacuum. The condensing surface is selected and held at a pre-determined temperature, so as to affect die crystallographic form of die condensate. If diis surface is at room teiiiperamre, a polycrystalline film is usually formed. As die temperature of die surface is increased die deposit crystal size increases, and can be made practically monocrystalline at elevated temperatures. The degree of crystallinity which has been achieved can be determined by electron diffraction, while odier properties such as surface morphology and dislocation sttiicmre can be established by electron microscopy. 

Elementar-analyse) /. elementary analysis, bestandteil) m. elementary constituent, -ladung) /. elementary charge, unit charge. stoff) m. elementary substance, element. Elementart) /. (Elec.) kind of element, type of cell. 

One gram-atom (or pound-atom) is the mass in grams (or pounds) of a given element that is numerically equal to its atomic weight. Thus, the number of gram-atoms of an elementary substance is m/A, where m is the mass (in grams) and A, its atomic weight. 

Avogadro s number represents the number of atoms (or molecules) present in one gram-atom (or gram-mole) of any elementary substance (or compound). It has a value of 6.02205 X 1023 [g3]... 

An element or elementary substance contains only one kind of atom. 

My interest in the periodic table has at least two aspects. Firstly, like so many people before me, I fell in love with the rational beauty of the periodic chart that appears to systematize all the kinds of elementary substances that a student of chemistry would ever encounter.1 The extent to which students are exposed to the periodic table and the stage at which this takes place seems to vary a good deal depending on geographical location and on the era in which they learn chemistry. In my own case it was in London in the 1960s where we were not initially taught the periodic table, although it was displayed on the classroom walls. 

The oxidation number of atoms in an elementary substance is zero. 

Dobereiner, J. W. (1829). An attempt to group elementary substances according to their analogies. Annalen der Physik und Chemie 15 301-307. 

For Laurent, who used metaphors of the chemical tree and the biological nucleus, the type was an ordering principle of extraordinary power. Berzelius was suspicious of this orientation because it was at odds with his theory of electrical polarities between elementary substances. 53... 

See O. Theodor Benfey, From Vital Force to Structural Formulas (Washington, D.C. American Chemical Society, 1975 1st ed., 1964) 34. As noted above, Lavoisier s 1789 tableaus include a table of "radicals" in which he surmised elementary substances stayed together as a group. 

While the use of an electrical or electrostatic theory of chemical affinity declined decade by decade in the nineteenth century, the theory began to experience a small revival on two fronts in the 1880s. One source of revival was the lecture that Helmholtz gave to a large audience at the Chemical Society of London in 1881. Helmholtz firmly associated himself with a theory of electrical "particles," namely, that the ions produced in electrolysis carry discrete and indivisible "atoms of electricity" that are independent of the elementary substance with which they combine. He further identified these atoms of electricity with indivisible units of chemical affinity "This is the modern chemical theory of quantivalence, comprising all the saturated compounds."Ill... 

The symbol 9 is called the characteristic temperamre and can be calculated from an experimental determination of the heat capacity at a low temperature. This equation has been very useful in the extrapolation of measured heat capacities [16] down to OK, particularly in connection with calculations of entropies from the third law of thermodynamics (see Chapter 11). Strictly speaking, the Debye equation was derived only for an isotropic elementary substance nevertheless, it is applicable to most compounds, particularly in the region close to absolute zero [17]. 

An element (or an elementary substance) is matter, the atoms of which are alike in having the same positive charge on the nucleus (or atomic number). 

In certain languages, a clear distinction is made between the terms element and elementary substance . In English, it is not customary to make such nice distinctions, and the word atom is sometimes also used interchangeably with element or elementary substance. Particular care should be exercised in the use and comprehension of these terms. 

Molecules can also be charged. This is not common in elementary substances, but where some molecules or atoms are positively charged (these as a class are called cations ) they must be accompanied by negative molecules or atoms (anions) to maintain electroneutrality. 

Many elements can give rise to more than one elementary substance. These may be substances containing assemblages of the same mono- or poly-atomic unit but arranged differently in the solid state (as with tin), or they may be assemblages of different polyatomic units (as with carbon, which forms diamond, graphite and the fullerenes, and with sulfur and oxygen). These different forms of the element are referred to as allotropes. Their common nomenclature is essentially trivial, but attempts have been made to develop systematic nomenclatures, especially for crystalline materials. These attempts are not wholly satisfactory. 

A name is given to each elementary substance, that is, each substance which has not been decomposed the name generally expresses some characteristic property of the substance, or tells something about its origin or the place of its discovery. The names of compounds are formed by putting together the names of the elements which combine to produce them and the relative quantities of these elements are indicated either by the use of Latin or Greek prefixes, or by variations in the terminal syllables of the names of the elements. 

The brown material, insoluble in water, examined more carefully [said he], was recognized to be the cause of the peculiar odor we mentioned above and by means of some experiments which we shall report soon, it was found that it was a combustible, elementary substance hitherto unknown, to which I have given the name selenium, derived from Selene (the moon), to recall its analogy with tellurium. According to its chemical properties, this substance belongs between sulfur and tellurium, although it has more properties in common with sulfur than with tellurium (9,17). 

First, they see it as one of the materials or principles of composition of bodies for, according to Stahls well summarized theory, the principle which chemists have called by names such as sulphur, sulphurous principle, flammable principle, flammable and coloring earth and by some other, less known names, which we will mention elsewhere, see Phlogistique, their principle, I say, is nothing else than fire itself —a pure and elementary substance, the true matter, the proper being of fire, the fire of Democritus and of some modern physicists. ... 

In an important paper entitled Experiments upon magnesia alba) quicklime, and other alcaline substances, published in 1755,1 J. Black first made clear the relations between caustic alkali and mild alkali that is, between the alkali hydroxides and alkali carbonates. These relations were not understood by the early chemists. They believed the mild alkalies and alkaline earths—that is, the carbonates of the alkalies and alkaline earths—to be elementary substances that the causticity of lime was due to the union of fire-matter or phlogiston with elemental chalk and the conversion of mild alkali into caustic alkali, with the simultaneous regeneration of chalk, by boiling the former with caustic lime, was due simply to the transfer of the phlogiston or fire-matter from the lime to the mild alkali. Otherwise expressed Quicklime=Chalk-f Fire-matter. J. Black proved this hypothesis to be untenable. H. L. Duhamel du Monceau 2 had shown nine years earlier in a memoir Diverses experiences sur la chaux, that limestone loses weight when calcined and regains it little by little on exposure to air. 

The Union of Two Elementary Substances.— The most obvious way in which to prepare a binary compound is by the union of the two constituent elements, though in many cases this is not the most practicable way. Sometimes, the elements are first prepared in pure form and are then combined in other cases, the preparation of the elements and their union is effected in one operation, as in the manufacture of calcium carbide and carborundum. In general, the more dissimilar the two elements the more likely they are to combine readily, but elements of the same general kind sometimes combine with ease, as is the case with chlorine and iodine, sulfur and phosphorus, or sodium and lead. 

The concept of a metal in the sense in which we use it—a distinct elementary substance of fixed and characteristic properties, chemical and physical—was never attained... 

The realization that substances are made up of definite masses of elementary substances, and that these might be... 

These are that matter is essentially eternal and indestructible that matter in its essential constitution consists of a few elementary substances and that from these by combinations all the varied forms of matter in the universe, as well as all organisms have been evolved that in these elementary particles or atoms, are inherent the properties which endow them with the possibilities of this development, and that this development is independent of any interference from supernatural sources, at least after the creative will has set in motion the process of development. 

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