## ::Formula

### ::concepts

Formula::formulas    Chemical::units    Volume::example    Science::number    Atoms::element    Mathrm::title

{{#invoke:Hatnote|hatnote}} {{#invoke:Multiple image|render}} In science, a formula is a concise way of expressing information symbolically as in a mathematical or chemical formula. The informal use of the term formula in science refers to the general construct of a relationship between given quantities. The plural of formula can be spelled either as formulas or formulae (from the original Latin).<ref name="oxford">Oxford Dictionaries: formula.</ref>

In mathematics, a formula is an entity constructed using the symbols and formation rules of a given logical language.<ref>{{#invoke:citation/CS1|citation |CitationClass=citation }}</ref> For example, determining the volume of a sphere requires a significant amount of integral calculus or its geometrical analogue, the method of exhaustion;<ref>{{#invoke:citation/CS1|citation |CitationClass=book }}</ref> but, having done this once in terms of some parameter (the radius for example), mathematicians have produced a formula to describe the volume: This particular formula is:

V = {{ safesubst:#invoke:Unsubst||\$B=4/3}} π r3

Having obtained this result, and knowing the radius of any sphere in question, we can quickly and easily determine its volume. Note that the volume V and the radius r are expressed as single letters instead of words or phrases. This convention, while less important in a relatively simple formula, means that mathematicians can more quickly manipulate larger and more complex formulas.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Mathematical formulas are often algebraic, closed form, and/or analytical.

In modern chemistry, a chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols, numbers, and sometimes other symbols, such as parentheses, brackets, and plus (+) and minus (−) signs.<ref>Atkins, P.W., Overton, T., Rourke, J., Weller, M. and Armstrong, F. Shriver and Atkins inorganic chemistry (4th edition) 2006 (Oxford University Press) ISBN 0-19-926463-5</ref> For example, H2O is the chemical formula for water, specifying that each molecule consists of two hydrogen (H) atoms and one oxygen (O) atom. Similarly, O denotes an ozone molecule consisting of three oxygen atoms and having a net negative charge.

In a general context, formulas are applied to provide a mathematical solution for real world problems. Some may be general: F = ma, which is one expression of Newton's second law, is applicable to a wide range of physical situations. Other formulas may be specially created to solve a particular problem; for example, using the equation of a sine curve to model the movement of the tides in a bay. In all cases, however, formulas form the basis for calculations.

Expressions are distinct from formulas in that they cannot contain an equals sign (=).<ref>{{#invoke:citation/CS1|citation |CitationClass=citation }}</ref> Whereas formulas are comparable to sentences, expressions are more like phrases.

Formula sections