We explain what an ionic bond is and its properties. Examples and applications of compounds formed with these types of bonds.
Sodium chloride (NaCl) is an ionic compound known as table salt.What is an ionic bond?
The ionic or electrovalent bond consists of the electrostatic attraction between particles with electrical charges of opposite signs called ions.
An ion is a particle electrically charged. It can be a atom or molecule who lost or won electrons, that is, it is not neutral.
This type of bond is generally manifested between metallic and non-metallic atoms in which the transfer of electrons occurs from the metallic atoms (less electronegative) to the non-metallic (more electronegative).
For an ionic bond to form it is necessary that the difference in electronegativity (the ability of an atom to attract electrons from another atom when they are combined in a Chemical bond) between both types of atoms is greater than or equal to 1.7 on the Pauling scale, used to classify atoms according to their electronegativity values.
Although the ionic bond is usually distinguished from the covalent one (consisting of sharing electronic pairs of the outer or valence shell of both atoms), in reality there is no pure ionic bond but this model consists of an exaggeration of thecovalent bond, useful for the study of atomic behavior in these cases. There is always some margin of covalence in these unions.
However, unlike the atoms that form the covalent bonds that often make up polar molecules, ions They do not have a positive and a negative pole, but a single charge predominates in them entirely. Thus, we will have cations when an atom loses electrons (remains positively charged) and anions when an atom gains electrons (remains negatively charged).
It can serve you:Metallic bond
Properties of ionic compounds
Some general characteristics of an ionic compound:
- They are strong links. The force of this atomic bond can be very strong, so the structure of these compounds tends to form very resistant crystal lattices.
- They are usually solid. TO temperatures and ranges ofPressure normal (T = 25ºC and P = 1atm), these compounds have a rigid, cubic molecular structure that forms crystalline networks that give rise to salts. There are also ionic liquids called "molten salts," which are rare, but extremely useful.
- They have a high melting and boiling point. As hemelting point(between 300 ºC and 1000 ºC) as that ofboiling of these compounds is usually very high, since large amounts of Energy to break the electrostatic attraction between the ions.
- Water solubility. Most salts are soluble in water and other aqueous solutions that have an electric dipole (positive and negative poles).
- Electrical conduction. In itssolid state they are not good conductors of electricity, since ions occupy very fixed positions in a crystal lattice. Instead, once dissolved in Water or in aqueous solution, they become effective conductors of the electricity.
- Selectivity. Ionic bonds can only occur betweenmetals of groups IA and IIA of the Periodic table, and the nonmetals of groups VIA and VIIA.
Examples of ionic bonding
- Fluorides (F–). Anions that are part of salts obtained from hydrofluoric acid (HF). They are used in the manufacture of toothpastes and other dental supplies.
Examples: NaF, KF, LiF, CaF2
- Sulfates (SO42-). Anions that are part of salts or esters obtained from sulfuric acid (H2SO4), whose union to a metal has diverse applications, from additives in obtaining construction materials, to supplies for contrast X-rays.
Examples: CuSO4, CaSO4, K2SO4
- Nitrates (NO3–). Anions that are part of salts or esters obtained from nitric acid (HNO3), used in the manufacture of the gunpowder and in numerous chemical formulations for fertilizers or fertilizers.
Examples: AgNO3, KNO3, Mg (NO3) 2
- Mercury II (Hg2 +). A cation obtained from mercury, also calledmercuric cationand that it is only stable in mediapH acid (<2). Mercury compounds are toxic to the human body, so they must be handled with certain precautions.
Examples: HgCl2, HgCN2
- Permanganates (MnO4–). The salts of permanganic acid (HMnO4) have an intense color purple and enormous oxidizing power. These properties can be used in the synthesis of saccharin, in the treatment of wastewater and in the manufacture of disinfectants.
Examples: KMnO4, Ca (MnO4) 2