chemical formula

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 [for´mu-lah] (pl. formulas, for´mulae) (L.)
1. an expression, using numbers or symbols, giving the directions for preparing a compound (such as a medicine) or giving a procedure to follow to obtain a desired result.
2. a mixture for feeding an infant, usually with cow's milk as a base, supplemented with vitamins and minerals. Various formulas are available, differing in protein, fat, and carbohydrate content in order to meet the nutritional requirements or restrictions of individual infants.
chemical formula a combination of symbols used to express the chemical components of a substance.
empirical formula a chemical formula that expresses the proportions of the elements present in a substance.
molecular formula a chemical formula expressing the number of each element present in a substance, without indicating how they are linked.
spatial formula (stereochemical formula) a chemical formula giving the numbers of atoms of each element present in a molecule of a substance, which atom is linked to which, the types of linkages involved, and the relative positions of the atoms in space.
structural formula a chemical formula showing the spatial arrangement of the atoms and the linkage of every atom.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

chem·i·cal for·mu·la

a statement of the structure of a molecule expressed in chemical symbols.
Farlex Partner Medical Dictionary © Farlex 2012


(for'myu-la) [L. formula, a register]
1. A rule prescribing ingredients and proportions for the preparation of a compound.
2. In chemistry, a symbolic expression of the constitution of a molecule. It consists of the symbols of its component elements, each denoting one atom, with subscripted numbers denoting the number of atoms present. Water, or H2O, consists of two molecules of the element hydrogen and one of oxygen. It may also be written HOH.

Collections of atoms that constitute a group by themselves (radical) are often separated by periods or parentheses. In this case, figures prefixed or appended to the parentheses, or prefixed to an expression contained within periods, apply to all the symbols embraced by the parentheses or periods. In all other cases, a figure prefixed to a symbolic expression for a molecule, such as a coefficient in an algebraic formula, is a multiplier of all the symbols following.

3. Any liquid diet containing variable amounts of protein, fat, carbohydrate, vitamins, and minerals administered to infants as an alternative or a supplement to breast milk.

Arneth's formula

An obsolete method of estimating the number of immature leukocytes by means of an elaborate differential blood count, on the basis of their shape and the number of lobes in the nucleus.

chemical formula

See: formula (2)

dental formula

A brief method of expressing the dentition of mammals in which the numbers of the teeth are given in the form of a fraction, each portion representing one quadrant; the numbers of the upper teeth form the numerator, and those of the lower teeth the denominator.

The first number listed represents the incisors; the second, the canines; the third, the premolars; and the fourth, the molars. The dental formula of the upper and lower right half of the mouth in humans is

empirical formula

A chemical formula that indicates the simplest numerical ratio of the elements within a molecule, without demonstrating the molecule's chemical bonds or structure. For example, the empirical formula for water is H2O. Synonym: molecular formula

molecular formula

Empirical formula.

official formula

A formula in a pharmacopeia.

spatial formula

Stereochemical formula.

stereochemical formula

A method of depicting chemical formulas so that the elements and their number are depicted as well as their position in space in relation to each other. Synonym: spatial formula

structural formula

A formula of a compound that shows the relationship of the atoms in a molecule. The atoms are shown joined by valence bonds (e.g., H-O-H) as opposed to the empirical formula (H2O).
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
Chemical Formula: [C.sub.8] [H.sub.10] [N.sub.4] [O.sub.2]
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The researchers then worked out the chemical formula of this substance.
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Each section is divided into four groups of materials, which are then further sub-divided according to their chemical formula. Resistance data are given as text, tables, and figures.