Elements Greek system

The first chemist to perform truly quantitative experiments was Robert Boyle (1627-1691), who carefully measured the relationship between the pressure and volume of air. When Boyle published his book The Skeptical Chymist in 1661, the quantitative sciences of physics and chemistry were bom. In addition to his results on the quantitative behavior of gases, Boyle s other major contribution to chemistry consisted of his ideas about the chemical elements. Boyle held no preconceived notion about the number of elements. In his view, a substance was an element unless it could be broken down into two or more simpler substances. As Boyle s experimental definition of an element became generally accepted, the list of known elements began to grow, and the Greek system of four elements finally died. Although Boyle was an excellent scientist. 

A phase is a region of material that has uniform physical and chemical properties. Phases are often given Greek symbols, like a or fi. But when a phase consists of a solid solution of an alloying element in a host metal, a clearer symbol can be used. As an example, the phases in the lead-tin system may be symbolised as (Pb) - for the solution of tin in lead, and (Sn) - for the solution of lead in tin. 

All chemical change is subject to the law of conservation of mass, including the conservation of the chemical elements making up the species involved, which is called chemical stoichiometry (from Greek relating to measurement (-metry) of an element (stoichion)). For each element in a closed reacting system, there is a conservation equa-... 

But want of originality did not help Etienne de Clave. His idea was heretical because it contradicted the system of elements propounded by the ancient Greeks and endorsed by Aristotle, their most influential philosopher. Aristotle took this scheme from his teacher Plato, who in turn owed it to Empedocles, a philosopher who lived during Athens s Golden Age of Periclean democracy in the fifth century bc. According to Empedocles there were four elements earth, air, fire, and water. 

Modified Forms in Common Use. There are numerous situations in which the foregoing system does not meet all requirements. In the formation uf binary compounds, several elements exhibit more Ilian two states of oxidation. One method, recommended by the IUPAC, of handling these situations is the use of prefixes derived from Greek to indicate stoichiometric composition, e.g., titanium dichloride, TiCL and dinitrogen oxide (nitrous oxide) N 0. Other accepted methods ofindicating proportions of constituents are the Stock system (oxidation number) and the Ewens-Bassett (charge number) system. 

Most Phase I oxidations are performed by cytochrome P-450. "Cytochrome," derived from Greek, literally means "colored substance in the cell." The color is derived from the properties of the outer electrons of the transition element iron. "P-450" denotes a reddish pigment with the unusual property of having its major optical absorption peak (Soret maximum) at about 450 nm, when it has been reduced and combined with carbon monoxide.330 Although the name "P-450" was intended to be temporary (until more was known about the substance), the terminology has persisted for 18 yr because of the increasing complexity of this enzyme system and because of the lack of agreement on new nomenclature. 

In spite of the complexity of the system, elemental sulfur and its incurable, confused nomenclature—literally almost the whole Greek alphabet has been misused to denote mixtures of largely unknown composition —there is one very important fact in this system. It is the fact that... 

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). 

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