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Chemical formula


The proposed means to execute something or resolve an issue is called formula . For the science, a formula is a brief form that expresses information symbolically . It is, in this sense, a fixed way of transmitting certain information.

The chemistry , for its part, is the science dedicated to the study of the composition, structure and properties of the matter . The changes experienced by it during certain reactions are also part of its business.

It is known as chemical formula to the representation of those elements that form a compound . The formula reflects the proportion in which these elements are found in the compound or the number of atoms that make up a molecule . Some formulas even provide information on how atoms bond through chemical bonds and how they are distributed in space.

To name a chemical formula you must follow the nomenclature rules that are called chemical formulation . A formula exhibits symbols and subscripts : the chemical formulation states that the symbols indicate the elements present in the compound and the subscripts indicate the amount of atoms present in the compound of each element.

It is possible to distinguish between different types of chemical formulas, some of which are set out below:

Empirical formula

This is the expression that shows the proportion in which atoms are found in a certain chemical compound, in the simplest way possible, which is why it is usually called minimum formula (represented as fm). It is worth mentioning that sometimes it coincides with the molecular formula (defined below).

A clear example of an empirical formula can be seen in the water molecule, which is represented as H2O, since for every two hydrogen atoms it contains one of oxygen (this is one of the cases in which the empirical formula coincides with the molecular). With ethane, on the other hand, both formulas are different: the empirical one is CH3; while the molecular one, C2H6.

Molecular formula

The molecular formula is used to indicate what type of atoms are in a given molecular compound, as well as the number of each class of atoms and its use is only correct in the case of covalent compounds (the union of two no metalsor of a non-metal with a metal and when they have an electronegativity difference of less than 1.7). Taking the case of ethane again, its molecular formula expresses that it has two carbon atoms and six of hydrogen, while the empirical one indicates that for every three of hydrogen there is one of carbon.

Semi-developed formula

It is a formula similar to the molecular one, but which indicates the links that exist between each group of atoms in the molecule, especially to highlight the functional ones. It is mainly used in organic chemistry, where it is easy to observe the structure of the carbon chain and each substituent.

Formula developed

It has a higher complexity than the previous one, since it shows all the links and represents them in a Cartesian plane, which facilitates the observation of some very important details of its structure.

Structural formula

What differentiates the structural formula from those exposed so far is that it indicates the geometry spatial of the molecule through distances, angles or the use of perspectives in 2 or 3 dimensional diagrams.

Lewis formula

Also called diagram or Lewis structure, shows the total number of atoms in a molecule, along with their respective valence electrons, which are represented by points or stripes. It is worth mentioning that its use is not recommended for highly complex structures.