Chemical Symbols

the abbreviated designation, by letters, of the chemical elements.

Modern chemical symbols (see Table 1.) consist of the first

letter or the first and one of the subsequent letters of the Latin name of the elements. In chemical formulas and chemical equations each chemical symbol expresses the relative weight (the atomic weight) in addition to the name of the element. The mass number is written at the upper left (sometimes upper right) of the chemical symbol to denote isobars and isotopes. The atomic number is written at the lower left. To denote the ion rather than the neutral atom, the ionic charge is written at the upper right. The number of atoms in a molecule of a given element is indicated at the lower right. For example, is a single-charged ion of a chlorine isotope (atomic number, 17; mass number, 35); is the diatomic molecule of the same isotope. The isobars of argon and calcium are denoted by and , respectively. The chemical symbols given in the table are international, but in some countries, symbols derived from the local names of the elements are used as well. For example, in France, instead of N for nitrogen, Be for beryllium, and W for tungsten, Az (azote), Gl (glucinium), and Tu (tungstene), respectively, have been adopted. In the United States, Cb (columbium) is often used in place of the symbol for niobium, Nb. The names and symbols for the elements with atomic numbers 102 and 103 (nobelium and lawrencium) have not yet been generally adopted.

Chemists of the ancient world and the Middle Ages used symbolic representations, letter abbreviations, and combinations of both (see Figure 1) to designate substances, chemical

Figure 1. Several chemical symbols of the 18th century (from J. C. P. Ehrchsleben, Nachal’nye osnovaniia khimii; translated from German to [Old] Russian by N. Sokolov, St. Petersburg, 1788, pp. 16–17). The sign for copper should be inverted (misprint in the original).

operations, and instruments. Seven metals of antiquity were represented by the astronomical signs of the seven celestial bodies: sun (gold), moon (silver), Jupiter (tin), Venus (copper), Saturn (lead), Mercury (mercury), and Mars (iron). Metals discovered between the 15th and the 18th century— bismuth, zinc, and cobalt—were designated by the first letters of their names. The symbol for ethyl alcohol (Latin, spiritus vini) consisted of the letters S and ∇. The symbols for nitric acid (Latin, aquafortis) and aqua regia (Latin, aqua regia’, a mixture of hydrochloric and nitric acids) consisted of the symbol for water V and capitals F and R, respectively. The symbol for glass (Latin, vitrum) was formed of two V’s, one inverted.

Attempts to systematize the old chemical symbols continued to the end of the 18th century. At the beginning of the 19th century the English chemist J. Dalton proposed that atoms of the chemical elements be designated by circles containing dots, dashes, the initial letters of the English names of metals, and so on. Dalton’s chemical symbols gained some acceptance in Great Britain and Western Europe, but they were soon displaced by the purely letter symbols proposed by the Swedish chemist J. J. Berzelius in 1814. The principles he advanced for formulating chemical symbols remain in effect to the present day. The first published report in Russia on Berzelius’ chemical symbols was made in 1824 by Moscow physician I. la. Zatsepin.