A bond between ions occurs with the definitive transfer of electrons, this bond is characterized by the existence of electrostatic attraction forces between ions. The attraction that exists between negative ions (anions) and positive ions (cations) gives rise to the ionic bond.
Compounds formed by ionic bonds are called ionic compounds. To exemplify, let's use the bond between Na and Cl, do you already know which substance is formed by the joining of these two elements? It is table salt (NaCl), which receives the scientific name of sodium chloride, the reaction that occurs for the formation you can see now.
The sodium atom (Na) is not stable, as it has 1 free electron in the valence shell, stability will only be achieved if it loses an electron, which will give rise to the Na cation+. The chlorine atom (Cl-) in turn is also not stable, for the same reasons as Na, and will reach stability only if it gains an electron, this atom gives rise to the Cl ion.-.
If the ions are already formed and electronically stable, then there will be an electrostatic interaction, better known as ionic bonding. This chemical phenomenon happens thanks to the rule: charges with opposite signs attract each other. See the equation:
At+ + Cl- → NaCl
The compounds derived from the ionic bond are called ionic compounds and have an electronically neutral structure.
Characteristics of ionic compounds:
- They have high melting point (M.P.) and boiling point (B.P.), this characteristic is explained by the crystalline arrangement of these compounds. The molecular arrangement of a bond is so tightly bound that intense heating is needed to break the crystal lattice arrangement, so the boiling point rises.
- Ionic compounds are electricity conductors, both those dissolved in water and those that are pure in the liquid state. There are ions in these compounds and as they have freedom of movement, they are attracted by the electrode, thus closing the electrical circuit.
- Solid ionic compounds at room temperature have a temperature of 25°C and a pressure of 1 atm, and the best solvent for these compounds is water.
By Líria Alves
Graduated in Chemistry
Brazil School Team
See more!
Ionic water balance
General chemistry - Chemistry - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/quimica/compostos-ionicos-definicao-caracteristicas-principais.htm
