There are various types of chemical bonds. Among them are covalent, metal, van der Waals, hydrogen and ion. Let's find out what an ionic bond is and what its properties are.
A chemical bond made by the transition of a common 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 the compound of atoms with strong electronegativity and metal atoms.
An atom of a metal gives off an electron without much difficulty and becomes a cation. And an electronegative atom, such as a halogen atom, easily accepts an electron, forming a negatively charged ion. These charged particles - anions and cations - form the one that has the name "ionic bond". Examples of it are sodium chloride, potassium bromide, lithium iodide and other metal halides (mainly alkaline).
But the compound cannot be formed by an ionic bond alone. The reason for this is the uncompensated
forces of attraction and repulsion. Therefore, it is worth talking only about the predominant ionic bond, while along with it there is another chemical bond. This is extremely important to know.
The ionic bond has no directivity and saturation properties. Examples of relationships with directivity and saturation are covalent, donor-acceptor bonds. Unsaturation and non-directivity of the ionic is manifested because when the ions are attached with a different charge, full charge compensation does not occur. Other counter-charged ions and so on may be attached. that is why around the ion there is the maximum possible number of people like it, but with a different sign. However, this number is limited due to the mutual repulsion of equally charged ions. Equilibrium is achieved with a certain relative position, which is characterized by a coordination number. This indicator depends on the ratio of the radii of the ions. Ion-bonded substances often have the coordination of a cube or octahedron and are crystals.
So, sodium chloride crystal - sodium chloride - has a cubic lattice. In it, each chlorine ion is associated with six sodium ions and each sodium ion is associated with six chlorine ions.
In alkali and alkaline earth metal oxides , an ionic bond is also observed. Examples of such compounds: calcium oxide, sodium oxide and others. Ions can consist not only of one atom, but of several. Inside such a complex ion is different, and between the ions themselves - an ionic bond. Examples: salts such as potassium sulfate (here potassium is a cation, sulfate ion is an anion).
It should also be noted that the properties of ions of substances are very different from the properties of atoms and molecules of these substances. So, for example, the chlorine ions that make up sodium chloride are colorless and odorless and suitable for food, while molecular chlorine - a greenish-yellow gas with a pungent odor - is poison. And sodium atoms with water react with an explosion, while ions dissolve freely.