What is an ionic bond? Examples of substances with it and its properties

There are different types of chemical bonding. Among them, covalent, metallic, van der Waals, hydrogen and ionic. Let's find out what the ionic bond and its properties are.

The chemical bond, realized by the transition of a general electron pair from one atom, less electronegative, to another, more electronegative, is what an ionic bond is. Examples of compounds formed by it can be combined by a common feature - the content in a compound of atoms with strong electronegativity and metal atoms.

The metal atom easily gives up the electron and becomes a cation. A electronegative atom, such as a halogen atom, easily takes an electron, forming a negatively charged ion. These charged particles - anions and cations - form the one that is called "ionic bond". Examples of it are sodium chloride, potassium bromide, lithium iodide and other metal halides (mostly alkaline).

But a compound can not be formed solely by an ionic bond. The reason for this is the uncompensated forces of attraction and repulsion. Therefore, it is worth talking only about the preferential ionic bond, while along with it there is another chemical bond. It is extremely important to know.

The ionic bond does not have directionality and saturation properties. Examples of links with directivity and saturation are covalent, donor-acceptor bonds. The unsaturation and non-directionality of the ionic one is manifested because the complete charge compensation does not take place when ions are attached to another charge. Other oppositely charged ions can be attached, and so on. This is why the maximum possible number of similar ions is located around the ion, but with a different sign. However, this number is limited due to the mutual repulsion of ions of equally charged. Equilibrium is achieved with their specific mutual arrangement, which is characterized by a coordination number. This index depends on the ratio of the radii of the ions. Substances with an ionic bond often have a coordination of a cube or an octahedron and are crystals.

So, the crystal of table salt - sodium chloride - has a cubic lattice. In it, each chloride ion is bound to six sodium ions and each sodium ion - with six chloride ions.

In the oxides of alkali and alkaline-earth metals , an ionic bond is also observed. Examples of such compounds are calcium oxide, sodium oxide and others. Ions can consist not only of one atom, but of several. Inside such a complex ion is another, and between the ions themselves is an ionic bond. Examples: salts of potassium sulfate type (here potassium is a cation, sulfate ion is an anion).

It should also be noted that the properties of the ions of substances differ greatly with the properties of the atoms and molecules of these substances. So, for example, chlorine ions, which are part of sodium chloride, do not have color and smell and are suitable for food, whereas molecular chlorine, a greenish-yellow gas with a sharp odor, is a poison. And the sodium atoms with water react with the explosion, while the ions freely dissolve.