Atomism, Greek

The notion that matter had ultimate constituents which could not be further subdivided goes back to the Greeks (atom = Greek a-tomos, not capable of being cut). Democritus (circa 460 BC - circa 370 BC), probably leaning on the ideas of... 

The eicosanoids are a group of signaling substances that arise from the C-20 fatty acid arachidonic add and therefore usually contain 20 C atoms (Greek eicosa = 20). As mediators, they influence a large number of physiological processes (see below). Eicosanoid metabolism is therefore an important drug target. As short-lived substances, eicosanoids only act in the vicinity of their site of synthesis (paracrine effect see p.372). 

Prostaglandins Prostaglandins, and the structurally related molecules prostacyclins, thromboxanes and leukotrienes, are called eicosanoids because they contain 20 carbon atoms (Greek eikosi = 20). These hormones are relatively short-lived and hence act locally near to their site of synthesis in the body. They are derived from the common precursor arachidonate (Fig. 2). This polyunsaturated fatty... 

Democritus (c. 460-370 bc), the father of atomism, focused on the ultimate components of all substances, and his reasoning went something like this If you cut a piece of, say, copper smaller and smaller, you must eventually reach a particle of copper so small that it can no longer be cut. Therefore, matter is ultimately composed of indivisible particles, with nothing between them but empty space. He called the particles atoms (Greek atomos, uncuttable ). However, Aristotle (384-322 bc) held that it was impossible for nothing to exist, and his influence suppressed the concept of atoms for 2000 years. 

C, b.p. 156 C. The most important of the terpene hydrocarbons. It is found in most essential oils derived from the Coniferae, and is the main constituent of turpentine oil. Contains two asymmetric carbon atoms. The (- -)-form is easily obtained in a pure state by fractionation of Greek turpentine oil, of which it constitutes 95%. Pinene may be separated from turpentine oil in the form of its crystalline nitrosochloride, CioHigClNO, from which the ( + )-form may be recovered by boiling with aniline in alcoholic solution. When heated under pressure at 250-270 C, a-pinene is converted into dipentene. It can be reduced by hydrogen in the presence of a catalyst to form... 

Friction can now be probed at the atomic scale by means of atomic force microscopy (AFM) (see Section VIII-2) and the surface forces apparatus (see Section VI-4) these approaches are leading to new interpretations of friction [1,1 a,lb]. The subject of friction and its related aspects are known as tribology, the study of surfaces in relative motion, from the Greek root tribos meaning mbbing. 

Ihe one-electron orbitals are commonly called basis functions and often correspond to he atomic orbitals. We will label the basis functions with the Greek letters n, v, A and a. n the case of Equation (2.144) there are K basis functions and we should therefore xpect to derive a total of K molecular orbitals (although not all of these will necessarily 3e occupied by electrons). The smallest number of basis functions for a molecular system vill be that which can just accommodate all the electrons in the molecule. More sophisti- ated calculations use more basis functions than a minimal set. At the Hartree-Fock limit he energy of the system can be reduced no further by the addition of any more basis unctions however, it may be possible to lower the energy below the Hartree-Fock limit ay using a functional form of the wavefunction that is more extensive than the single Slater determinant. 

The lUPAC rules assign names to unbranched alkanes as shown m Table 2 2 Methane ethane propane and butane are retained for CH4 CH3CH3 CH3CH2CH3 and CH3CH2CH2CH3 respectively Thereafter the number of carbon atoms m the chain is specified by a Latin or Greek prefix preceding the suffix ane which identifies the com pound as a member of the alkane family Notice that the prefix n is not part of the lUPAC system The lUPAC name for CH3CH2CH2CH3 is butane not n butane... 

It IS convenient to use the Greek letters a p 7 and so forth to locate the carbons m a molecule m relation to the carbonyl group The carbon atom adjacent to the carbonyl carbon is the a carbon atom the next one down the chain is the p carbon and so on Butanal for example has an a carbon a p carbon and a y carbon... 

A bridging group should be indicated by adding the Greek letter p immediately before its names and separating this from the rest of the complex by a hyphen. The atom or atoms of the characteristic element to which the bridging atom is bonded, is indicated by numbers. 

The system for naming the straight-chain hydrocarbons is based on an agreed-upon method of retaining the first three or four common names, then using Greek prefixes that indicate the number of carbon atoms in the chain. For isomers, the same system is used, always using the name of the compound that is attached to the chain and the name of the chain. 

Iodine (from the Greek, iodines, meaning violet) has an atomic weight of 126.9044, atomic number 53, melting point 113.5° C, and boiling point 184.35° C. As a gas,... 

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