chemical formula

Chemistry

2022

We explain what a chemical formula is, the types that exist, examples and their parts. Also, chemical symbols and elements.

Chemical formulas are used to express what happens during a chemical reaction.

What is a chemical formula?

A chemical formula is a graphic expression of the elements that make up a chemical compound anyone. The formulas express the numbers and the proportions his atoms respective and, in many cases, also the type of chemical links that unite them. To each molecule and / or known compound corresponds to a chemical formula, as well as a name from it according to the rules of the chemical nomenclature.

There are different types of chemical formulas, each one focused on a certain type of information, but in general all of them serve to understand the chemical nature of the substances and to express what happens during a chemical reaction determined, in which some elements or compounds they transform into others. For this reason, chemical formulas respond to a conventional system of representation of the elements and the molecules, that is, to a specialized technical language.

Chemical formulas use the chemical symbols of the elements and logical proportions between them, expressed by mathematical symbols.

Types of chemical formula

A semi-developed formula expresses the bonds and their type between each molecule of the compound.

There are different types of chemical formula, useful to provide different information.

  • Molecular formula. It is a fairly basic type of formula that expresses the type of atoms present in a covalent compound and the amount of each. It uses a linear sequence of symbols from the chemical elements and numbers (as subscripts). For example, the molecular formula of glucose is C6H12O6 (six atoms of carbon, twelve of hydrogen, and six of oxygen).
  • Semi-developed formula. Similar to the molecular formula, it is a type of formula that expresses the atoms that make up the compound and also expresses the chemical bonds (lines) and their type (single, double, triple) between each atom of the compound. Carbon-hydrogen bonds are not represented in this formula. This is useful to identify the radical groups that make it up, as well as its chemical structure. For example, the semi-developed formula for glucose is, CH2OH - CHOH - CHOH - CHOH - CHOH - CHO.
  • Developed formula. The developed formula is the next step in complexity from the semi-developed one. This representation indicates the bond and the location of each atom of the compound within its respective molecules, in a Cartesian plane, representing the entirety of the structure of the compound.
  • Structural formula. In order to represent molecules not only in their structure and organization but also in their spatial form, an even more complex formula is needed, which uses two- or three-dimensional perspectives.
  • Lewis formula. Also called "Lewis diagrams" or "Lewis structures", it is a representation similar to the formula developed for a compound, but that indicates the respective electrons shared in each chemical bond between atoms, according to the Valencia of the elements involved. These electrons are represented by points linked to a line where there is a bond. Unshared electrons are also represented using dots on the corresponding atom. They are very specific and technical formulas.

Examples of chemical formula

Some examples of the chemical (molecular) formula of known compounds are:

  • Oxygen. O2
  • Ozone. O3
  • Carbon dioxide. CO2
  • Carbon monoxide. CO
  • Water. H2O
  • Ammonia. NH3
  • Methane. CH4
  • Propane. C3H8
  • Sulfuric acid. H2SO4
  • Hydrochloric acid. HCl
  • Sodium chloride. NaCl
  • Sodium bicarbonate. NaHCO3
  • Formaldehyde. CH2O
  • Benzene. C6H6
  • Saccharose. C12H22O11
  • Cal. CaO
  • Ethyl alcohol. C2H5OH
  • Monosodium glutamate. C5H8NNaO4
  • Penicillin. C16H18N2O4S

Parts of a chemical formula

Compounds often show some structural and functional recurrence.

Chemical formulas are made up of chemical symbols (letters) and subscripts (numbers), which express the type of atoms present in the substance and their quantity. However, in certain fields of chemistry (such as organic chemistry), compounds show a certain structural and functional recurrence, which makes it possible to identify fragments of the molecule. These fragments are called "radicals" (molecular units with free electrons) or "functional groups" (atoms or molecular units responsible for the substance reacting in a certain way).

Examples of functional groups are: hydroxyl (-OH), carbonyl (= C = O), carboxyl (-COOH), among others.

Examples of radicals are: methyl (-CH3), ethyl (CH3CH2-), among others.

Chemical symbols

Chemical symbols are the minimum pieces that make up any chemical formula and represent each of the various chemical elements known to the humanity, that is, the different types of atoms that known matter is composed of.

Each chemical element has a particular chemical symbol (generally derived from its historical Latin name).

Some examples of chemical symbols are:

  • Carbon. C
  • Oxygen. OR
  • Match. P
  • Hydrogen. H
  • Nitrogen. N
  • Iodine. I
  • Iron. Faith
  • Lead. Pb
  • Aluminum. To the
  • Selenium. I know
  • Plutonium. Pu

Chemical elements

The elements can be grouped according to their chemical properties.

Chemical elements are the different types of atoms that make up the matter and that are distinguished from each other according to the particular configuration of their subatomic particles (protons, neutrons Y electrons).

The elements can be grouped according to their chemical properties, that is, to the forces to which they respond more or less easily, to the behavior they exhibit in certain reactions, or to other structural characteristics of their own.

An example that well illustrates the definition of a chemical element is the following: the 12C, 13C and 14C isotopes are some of the isotopes of the chemical element carbon (C).

Chemical elements are represented, classified and organized in the Periodic table of the elements.

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