• Monday January 25,2021


We explain to you what an ion is and how these molecules can be constituted. In addition, examples of ions and what an anion is.

An ion is a molecule that has gained or lost electrons.
  1. What is an ion?

In chemistry, an ion is known as an electrically charged molecule consisting of an atom or molecule that is not electrically neutral, that is, , who in their constitution have gained or lost electrons (ionization).

The ions can consist of two or more atoms (polyatomic) of different nature, or of a single atom (monoatomic). In any case, we will talk about a cation (or cations) when it is a positively charged ion (i.e., lacking electrons), and we will talk about an anion (or anions) when it is a negatively charged ion (it is say: with excess electrons).

Other types of ions are also known, based on their electrical charge, known as dianions (when they have both electric charges), zwitterions (which has a neutralized double charge to reach the neutral), or ionic radicals (free ions of enormous reactivity and instability ). In general, ions are very reactive and tend to be joined by electromagnetism with other molecules.

Ions play an indispensable role in life, especially those of calcium, potassium and sodium, whose importance in the transit of cell membranes and neurotransmitters has been studied extensively. For the rest, the understanding of ions It has allowed us to develop plasma technology and even measure water quality based on the ionic salts dissolved in it.

See also: Chemical Link.

  1. Ion examples

Azide is a simple anion.

The best known ions are:

Simple cations Composed of a single atom with positive charge:

  • Aluminum (Al3 +)
  • Cesium (Cs +)
  • Chromium III or chromic ion (Cr3 +)
  • Chrome VI or perchromic ion (Cr6 +)
  • Hydrogen or proton (H +)
  • Helium or alpha particle (He2 +)
  • Lithium (Li +)
  • Iron II or ferrous ion (Fe2 +)
  • Iron III or ferric ion (Fe3 +)
  • Nickel III or nickel ion (Ni3 +)
  • Tin II or stannous ion (Sn2 +)
  • Tin III or static ion (Sn3 +)

Polyatomic cations . Composed of two or more atoms with positive charge:

  • Ammonium (NH4 +)
  • Oxonium (H3O +)
  • Nitronium (NO2 +)
  • Mercury I or mercury ion (Hg22 +)

Simple anions . Composed of a single atom with negative charge:

  • Azide (N3-)
  • Bromide (Br-)
  • Carbide (C4-)
  • Chloride (Cl-)
  • Fluroride (F-)
  • Phosphide (P3-)
  • Nitride (N3-)
  • Sulfide (S2-)

Oxoanions Composed of oxygen and other elements, they have a negative charge:

  • Arsenate (AsO43-)
  • Borate (BO33-)
  • Hypobromite (BrO-)
  • Bicarbonate (HCO3-)
  • Chlorate (ClO3-)
  • Chlorite (ClO2-)
  • Hypochlorite (ClO-)
  • Dichromate (Cr2O72-)
  • Hydrogen sulfate or bisulfate (HSO4-)
  • Hydrogen sulphite or bisulfite (HSO3-)
  • Silicate (SiO44-)

Anions of organic acids . Coming from organic molecules, they have a negative charge:

  • Acetate (C2H3O2-)
  • Oxalate (C2O42-)
  • Bioxalate (HC2O4-)

Other anions With negative charge and more than one atom:

  • Bisulfide (HS-)
  • Amiduro (NH2-)
  • Cyanato (OCN-)
  • Thiocyanate (SCN-)
  • Cyanide (CN-)
  • Hydroxide (HO-)
  1. Anion

Sulfite is a polyatmic anion.

It is known as anion (or anions) to ions that have a negative electrical charge, that is, they have gained electrons in a chemical reaction that gave rise to them. They may be constituted by one or several atoms, but even in the latter case the overall charge of the molecule (its oxidation state) is always negative.

There are three types of anions:

  • Monoat micos . Those constituted by a single atom that has gained electrons. For example: Chloride (Cl-).
  • Polyatics . They come from a molecule that has gained electrons in a chemical reaction, or from an acid that has lost protons. For example: Sulfite (SO32-).
  • Acids . They come from a polyprotic acid (which have multiple ionizable hydrogen) to which protons have been extracted. : Phosphate (H2PO4-).

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