Elements or elementary substances

Name of an element of indefinite molecular formula or structure 

A sample of an element that has an undefined formula, or is a mixture of allotropes (see Sections IR-3.4.2 to IR-3.4.5), bears the same name as the atom. 

Allotropic modifications of an element bear the name of the atom from which they are derived, together with a descriptor to specify the modification. Common descriptors are Greek letters (a, (3, y, etc.), colours and, where appropriate, mineral names (e.g. graphite and diamond for the well known forms of carbon). Such names should be regarded as provisional, to be used only until structures have been established, after which a rational system based on molecular formula (see Section IR-3.4.3) or crystal structure (see Section IR-3.4.4) is recommended. Common names will continue to be used for amorphous modifications of an element and for those which are mixtures of closely related structures in their commonly occurring forms (such as graphite) or have an ill-defined disordered structure (such as red phosphoms) (see Section IR-3.4.5). 

Systematic names are based on the number of atoms in the molecule, indicated by a multiplicative prefix from Table IV. The prefix mono is only used when the element does not normally occur in a monoatomic state. If the number is large and unknown, as in long chains or large rings, the prefix poly may be used. Where necessary, appropriate prefixes (Table V) may be used to indicate structure. When it is desired to specify a particular polymorph of an element with a defined structure (such as the a-, (3- or y-forms of Sg) the method of Section IR-3.4.4 should be used (see Examples 13-15 in Section IR-3.4.4). 

In Example 12, the name [60]fullerene is to be regarded as an acceptable non-systematic name for a particular C6o structure. For more details see Section P-27 of Ref. 6. 

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

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. 

Name of an element or elementary substance of definite motneutar formula or strut ture. These are named by adding the appropriate numerical prefix [see above] to the name of the atom to designate the number of atoms in the molecule. The prefix mono is not used except when the element does not normally exist in a monoatonuc state. 

IR-3.3.1 Isotopes of an element IR-3.3.2 Isotopes of hydrogen IR-3.4 Elements (or elementary substances)... 

Chemistry involves studying the properties and behavior of matter. Matter is the physical material of tiie universe it is anything fliat has mass and occupies space. This book, your body, the clothes you are wearing, and toe air you are breathing are all samples of matter. Not all forms of matter are so common or so familiar, but countless experiments have shown toat toe tremendous variety of matter in our world is due to combinations of only about 100 very basic or elementary substances called elements. As we proceed through this text, we will seek to relate toe properties of matter to its composition, toat is, to the particular elements it contains. 

Were there any arguments about the implications of the periodic law for the structure of matter Was the periodic law related to controversies concerning atomic theory Was it associated with other ideas about the nature of matter, such as elements vs. elementary substances, or more general theories of the universe, such as evolutionism and cosmology ... 

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. 

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. 

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). 

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. 

Plato s elements can be interconverted because of the geometric commonalities of their atoms . For Anaxagoras, all material substances are mixtures of all four elements, so one substance changes to another by virtue of the growth in proportion of one or more elements and the corresponding diminution of the others. This view of matter as intimate blends of elements is central to the antiquated elementary theories, and is one of the stark contrasts with the modern notion of an element as a fundamental substance that can be isolated and purified. 

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. 

Thus an elementary substance is composed of one element. A compound is composed of two or more elements. 

Elementary substance—a substance containing atoms of one kind oiih Compound—a substance containing two or mc )re kinds of atoms in a definite ratio. The 98 elements, their names and symbols. 

The 98 known elements include some with which everyone is familiar and many which are rare. Some of the elementary substances are metals, and some are non-metals at room temperature some are gases, some are liquids, and some are solids. They show extremely great variety in their chemical properties and in the nature of the compounds which they form. In consequence the study of chemistry is not simple or easy to obtain a reasonably broad knowledge of general chemistry it is necessary to learn a great many facts. 

The existence of an elementary substance in two forms is called allotropy (Greek alldtropia, variety, from alios, other, and tropos, direction). Ordinary oxygen and ozone are the allotropes of oxygen. Allotropy is shown by many elements it is due either to the existence of two or more kinds of molecules (containing different numbers of atoms) or to the existence of two or more different crystalline forms that is, of different arrangements of the atoms or molecules in a crystalline array. 

A symbol such as Cu is used to indicate the element topper, either in the elementary substance or in compounds. It also ipeans a definite amount of copper—one atom or onfc atomic weight (63.57) in any... 

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