Symbols, chemical notation

Bolton, Henry Carrington. History of chemical notation, Part I., Metallurgic astronomy and its symbols. Trans NY Acad Sci 2, no. 5 (11 Dec 1882) 53-57. 

An internationally accepted chemical notation makes use of symbols to represent elements and compounds, and advises on naming chemical compounds. In this notation, the elements are represented by one or two letters, many of which are drawn from the elements Latin or Greek names. The number of atoms of an element in a molecule is represented by a subscript written after the symbol thus Au (the first two letters of aurum, the Latin name for gold) represents an atom of gold Cu (the first two letters of cuprum, the Latin name for copper), an atom of copper and C (the first letter of carbon), an atom of carbon O represents an atom of oxygen and 02, a molecule of oxygen. The symbols listed below provide examples of the presently accepted form of chemical notation ... 

Benjamin Brodie, a professor of chemistry at Oxford University, renewed the project for algebraic reform of chemical formulas in a paper presented to the Chemical Society of London in 1867. Chemists recognized the aim of the project to be a "strictly philosophical system of chemical notation by means of actual formulae instead of mere symbols."69 But again, there was little... 

Many researchers have recognized the importance of having an unambiguous grammar for chemical notation, but they have mainly applied WLN [8] to on-line compound search [9] and structural summary (identification of common structural features) [10]. Johns and Clare point out that it is a linguistic rather than merely a symbolic notation. This means that the symbols are represented and manipulated in well defined structures. This section relies on the unambiguousness of WLN to recognize parent molecules while Section 5 relies on the WLN rules to actually manipulate symbol structures. 

Jons Jakob Berzelius (1779-1848), a Swedish chemist, is also considered one of the founders of modern chemistry. He prepared, purified, and identified more than 2,000 chemical elements and compounds. He also determined the atomic weight (mass) of several elements and replaced pictures of elements with symbols and numbers, which is the basis of our chemical notations today. 

Electrons in the outermost occupied shell of any atom may play a significant role in that atoms chemical properties, including its ability to form chemical bonds. To indicate their importance, these electrons are called valence electrons (from the Latin valentia, strength ), and the shell they occupy is called the valence shell. Valence electrons can be conveniently represented as a series of dots surrounding an atomic symbol. This notation is called an electron-dot structure or, sometimes, a Lewis dot symbol, in honor of the American chemist G. N. Lewis, who first proposed the concepts of shells and valence electrons. Figure 6.2 shows the electron-dot structures for the atoms important in our discussions of ionic and covalent bonds. (Atoms of elements in groups 3 through 12 form metallic bonds, which we ll study in Chapter 18.)... 

The above examples use the abstract element symbols Pi, Gi2, etc. Briefly let us show how this system will operate with real monomers, polymers, and multipolymer combinations, using chemical notation instead of the elements but retaining the binary operation notation. 

Information about an element s protons and neutrons is often summarized using the chemical notation shown in Figure 2.3. The letter X represents the atomic symbol for an element. (The atomic symbol is also called the element symbol.) Each element has a different atomic symbol. All chemists, throughout the world, use the same atomic symbols. Over the coming months, you will probably learn to recognize many of these symbols instantly. Appendix G, at the back of this book, lists the elements in alphabetical order, along with their symbols. You can also find the elements and their symbols in the periodic table on the inside back cover of this textbook, and in Appendix C. (You will review and extend your understanding of the periodic table, in section 2.2.)... 

Because the theory is primarily chemically oriented, we use a left-to-right notation. In mathematics the operation is written generally to the left of the symbol upon which it operates—2X and (d/dy)X. Chemical notation usually reads from left to right—HC1 -f NaOH — NaCl -f H20. Thus mP indicates the addition of a monomer followed by its polymerization. The combination pC indicates taking a previously formed polymer and crosslinking it. 

When it comes to physicochemical (biological) properties the common structural formulae obscure rather than explain the problem. One of the most convincing examples may be the anaesthetic activity of chemicals. Among general anaesthetics one can identify such diverse chemical families like hydrocarbons, alcohols, ethers, barbiturates, nitrous oxide, steroids, etc. Each one must have anaesthetic activity encoded in its structure but how is it discovered using conventional chemical symbolic The planar or three-dimensional chemical notation can be an obstacle to making a breakthrough in chemistry. 

A compilation of symbols used in chemical notation appears in Appendix B. 

Appendix B Symbols and Abbreviations Used in Chemical Notation... 

Skill 6.2 Interpreting symbols and chemical notation for elements, isotopes, ions, molecules, and compounds... 

Our journey into the center of the atom begins with a brief review. You learned in Chapter 2 that the protons and neutrons in each atom are found in a tiny, central nucleus that measures about 1/100,000 the diameter of the atom itself You also learned that the atoms of each element are not necessarily identical they can differ with respect to the number of neutrons in their nuclei. When an element has two or more species of atoms, each with the same number of protons but a different number of neutrons, the different species are called isotopes. Different isotopes of the same element have the same atomic number, but they have a different mass number, which is the sum of the numbers of protons and neutrons in the nucleus. In the context of nuclear science, protons and neutrons are called nucleons, because they reside in the nucleus. The atom s mass number is often called the nucleon number, and a particular type of nucleus, characterized by a specific atomic number and nucleon number, is called a nuclide. Nuclides are represented in chemical notation by a subscript atomic number (Z) and superscript nucleon number (A) on the left side of the element s symbol (X) ... 

Opinions of ancient philosophers, and of moderns antecedently to the epoch of Dalton, with respect to the constitution of matter Views of Dalton, and of other philosophers subsequently, with respect to the laws of combination betwixt matter, and its intimate constitution On chemical symbols and notation On the existence of atoms On the mode of combination betwixt atoms On isomorphous bodies On isomeric bodies ... 

Briefly, notation systems attempt to record full, multidimensional structural descriptions in a linear form, by the use of more comprehensive symbols than atoms and bonds (e.g. symbols for particular chains, rings, functional groups). Thus, more information is recorded implicitly, in Uie rides of the notation, and less is recorded explicitly in the notations for individual compounds. The rules can therefore be quite complicated, in order to ensure the notations are unique and unambiguous. For the Wiswesser Line Notation, the rules are given in Smith, E. G. The Wis-wesser Line-Formula Chemical Notation. New York McGraw-Hill 1968. In this notation, for example, saturated carbon chains are simply indicated by an arable numeral equal to the number of carbons in the chain, branch-... 

The free radical reactions below have been classified into three main categories those which increase the number of free radicals, those which conserve, and those which decrease the number of free radicals. A two-letter index has been given beside the descriptive term of the reaction which will be used when generating mechanisms. The meaning of the symbols +M and (+M) will be commented on in paragraph 2. The examples are presented with the NANCY linear chemical notation described in the appendix NOTATIONS at the end of the book. 

Carbon has seven known isotopes. Three of these have six, seven, and eight neutrons, respectively. Write the complete chemical notation for these three isotopes, giving mass number, atomic number, and symbol. 

The nomenclature committee of the American Society for Testing Materials (1957) proposed a nomenclature which expresses the chemical formula followed by the number of atoms per unit cell and the Bravais lattice symbol. This notation was later developed by Schubert (1964) and by Pearson (1967). This symbology may be used for classification purposes and might help to find out if a particular structure type had been determined before, but it does not contain information on the geometry of the structure. 

The Fluctuation Theory of Solutions—also known as Fluctuation Solution Theory, Kirkwood-Buff Theory, or simply Fluctuation Theory— provides an elegant approach relating solution thermodynamics to the underlying molecular distributions or particle number fluctuations. Here, we provide the background material required to develop the basic theory. More details can be found in standard texts on thermodynamics and statistical mechanics (Hill 1956 Munster 1970). Indeed, the experienced reader may skip this chapter completely, or jump to Section 1.2. A list of standard symbols is also provided in the Prolegomenon to aid the reader, and we have attempted to use the same set of symbols and notations in all subsequent chapters. Throughout this work we refer to a collection of species (1, 2, 3,...) in a systan of interest. We consider this to represent a primary solvent (1), a solute of interest (2), and a series of additional cosolutes or cosolvents (3,4,...) which may also be present in the solution. However, other notations such as A/B or u/v is also used in the various chapters. All summations appearing here refer to the set of thermodynamically independent components (n in the mixture unless stated otherwise. Derivatives of the chemical potentials with respect to composition form a central component of the theory. The primary derivative of interest here is defined as... 

Rouvray DH. The changing role of the symbol in the evolution of chemical notation. Endeavor 1977 1 23-31. 

The conventional spectrosct k notation fcx- zero-valent actinium is Ac L Similarly, the singly ionized species is Ac II, and the doubly charged, Ac ID. The chemkal notation for the latter is Ac Ac(u). I en referring to free-ion spectra we will use the spectroscopic notation. When indicating the valence state of an ionic species in a condensed phase we will use the chemical notation. We use the symbol An to represent any actinide element, Ln as the general symbol for the lanthanides. 

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