Roman type symbols

Symbols separated by commas represent equivalent recommendations. Symbols for physical and chemical quantities should be printed in italic type. Subscripts and superscripts which are themselves symbols for physical quantities should be italicized all others should be in Roman type. Vectors and matrices should be printed in boldface italic type, e.g., B, b. Symbols for units should be printed in Roman type and should remain unaltered in the plural, and should not be followed by a full stop except at the end of a sentence. References International Union of Pure and Applied Chemistry, Quantities, Units and Symbols in Physical Chemistry, Blackwell, Oxford, 1988 Manual of Symbols and Terminology for Physicochemical Quantities and Units, Pure Applied Chem. 31 577-638 (1972), 37 499-516 (1974), 46 71-90 (1976), 51 1-41, 1213-1218 (1979) 53 753-771 (1981), 54 1239-1250 (1982), 55 931-941 (1983) lUPAP-SUN, Symbols, Units and Nomenclature in Physics, PV ica 93A 1-60 (1978). 

SI units and their symbols have distinctive type styles. Items given in italic type are variables, quantity symbols, superscripts and subscripts if they represent variables, quantities, or running numbers. Items given in roman type are unit symbols, superscripts, and subscripts that are descriptive. The typeface used in the surrounding text of the document does not change these rules. 

Symbols for the chemical elements are not treated as abbreviations. They need not be defined, and they are typeset in roman type. (See Table 13-1 on p 270 f.)... 

Do not confuse abbreviations and mathematical symbols. An abbreviation is usually two or more letters a mathematical symbol should generally be only one letter, possibly with a subscript or superscript. An abbreviation may be used in narrative text but seldom appears in equations a mathematical symbol is preferred in equations and may also be used in text. For example, in text with no equations, PE may be used for potential energy, but in mathematical text and equations, p is preferred. Abbreviations are typeset in roman type most mathematical symbols are typeset in italic type. 

Use italic type for subscripts and superscripts that are themselves symbols for physical quantities or numbers. Use roman type for subscripts and superscripts that are abbreviations and not symbols. 

The names of chemical compounds may consist of one or more words, and they may include locants, descriptors, and syllabic portions. Locants and descriptors can be numerals, element symbols, small capital letters, Greek letters, Latin letters, italic words and letters, and combinations of these. Treat the word or syllabic portions of chemical names just like other common nouns use roman type, keep them lowercase in text, capitalize them at the beginnings of sentences and in titles, and hyphenate them only when they do not fit completely on one line. 

When element symbols are used with a type of reaction as a noun or adjective, use roman type for the symbol and hyphenate it to the word that follows it. 

Write the symbols for the chemical elements in roman type with an initial capital letter. 

Symbols for physical quantities should be single-lettered using the Latin or Greek alphabet. The letters may be capital or lower case but should be printed in italic (slanted) type. Subscripts and superscripts may be added for clarity. All subscripts and superscripts are printed in Roman type (upright) except when these are symbols for physical quantities and therefore printed in italic type. Symbols for units should always be printed in Roman type. Similarly, symbols for chemical elements, elementary particles and mathematical operators (e.g. sin, exp, In, d/dr, etc.) are also printed in Roman type (see sections 1.3 and 1.6 in [1]). 

Symbols for (physical) quantities, be they variables or constants, are given by a single character (generally Latin or Greek letters) and are printed in italics, e.g., F (force), p (pressure), p (chemical potential), k (Boltzmann constant). Further differentiation is achieved by the use of subscripts and/or superscripts these are printed in italics if it concerns the symbol of a quantity, otherwise in roman type, e.g., cp (specific heat at constant pressure), hp (Planck s constant), Ffu (surface dilational modulus). For clarity, symbols are generally separated by a (thin) space, e.g., F=ma, not ma. Some generally accepted exceptions occur, such as pH, as well as symbols (or two letter abbreviations, rather) for the dimensionless ratios frequently used in process engineering, like Re for Reynolds number and Tr for Trouton ratio (in roman type). 

Point groups, crystallographic, 261 -262 Points as type size measure, 287 Points (geometric), use of roman type, 152 Polycyclic aromatic compounds, 234 Polymer chemistry, symbols and SI units, 2761... 

Note that the symbol for a physical quantity is always printed in italics, while a symbol for a unit is printed in roman type. Luminous intensity is seldom used in physical chem try, but the other units are of importance and are considered in further detail later. 

For the most part the units, symbols, and terminology recommended by the International Union of Pure and Applied Chemistry and based on the Systeme Internationale (SI) have been used. A brief account of the SI is given in Appendix A (p. 556), Note that symbols for quantities are printed in italics, symbols for units in roman type. Non-SI units have been retained in a few cases—in particular calorie, atmosphere, and molarity—in view of the widespread use of them in chemical and biological work. 

The symbol for a physical quantity is always given in italic (sloping) type, while symbols for units are given in roman type. Column headings in tables and axis labels on graphs may conveniently be written as the physical quantity symbol divided by the unit symbol, e.g. ... 

The symbols for the unit and any prefix are both printed in roman type with no space between them. The symbol for the unit is followed by a period only if it ends a sentence and is never plural. Thus... 

Chemical species and units of physical quantities are denoted by Roman type characters, whereas physical quantities that can be expressed by numerical values are denoted by Greek or italic characters. Mathematical symbols have their usual meaning and are not listed here. The same symbol is used for an extensive property of a system and for the molar quantity of a constituent of the system. The SI system of physical units is used throughout, but some extra SI units commonly used in the physicochemical literature are also included where they simplify the notation. These include the symbols °C for centigrade temperatures (T/K-273.15), M for mol-dm , and m for mol (kg solvent)". ... 

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