chemical formula

combination of symbols representing the composition of a chemical substance

A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. A chemical formula is also a short way of showing how a chemical reaction occurs. For molecular compounds, it identifies each constituent element by its chemical symbol and indicates the number of atoms of each element found in each discrete molecule of that compound. If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol (although 19th-century books often used superscripts). For ionic compounds and other non-molecular substances, the subscripts indicate the ratio of elements in the empirical formula.
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Noun
1. a representation of a substance using symbols for its constituent elements
(synonym) formula
(hypernym) statement
(hyponym) molecular formula
(part-meronym) chemical notation

Definition

The format for the chemical formula is based on the reported formula from the literature source for the mineral. In many cases, the formula is base on the structural interpretation of the mineral, especially the silicates.

The chemical formula is closely matched to the mineral's crystallographic unit cell dimensions and "Z" value.

Special symbols are used where a hole (vacancy) is present in the formula. For this database, the "[ ]" square brackets are used to signify this vacancy.
e.g.: ([ ],Fe,Mg)(Mg,Al,Fe)5Al4Si2(Si,Al)2(B,Si,Al)(O,OH,F)22
Rare Earth Elements in mineral formulae are denoted by the symbol REE.
e.g.: (Na3(Ca,REE,Sr)3(CO3)5)

Compare with empirical formula .A notation that indicates the type and number of atoms in a molecule. The molecular formula of glucose is C6H12O6, which indicates that a molecule of glucose contains 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.