Formation of Electrovalent Bond - Ionic bond

Formation of Electrovalent Bond - Ionic bond

Electrovalent bond (or) Ionic bond :The electrostatic force of attraction which binds two or more oppositely charged ions formed by the transfer of electron/s from the metal atom to the non metal atom.

Electrovalent compound: The compounds formed as a result of the transfer electrons.

Electrovalency: The number of electrons lost or gained by an atom of an element to attain stability.

The electrovalent bond is possible between a metal and a non metal. The metal atom atom loses electron/s to nonmetal atom so that the metal and the nonmetal attain stable electronic configuration.

ü  As the metal loses electron/s it is oxidized and forms a cation (positive ion).

Oxidation:

Na – e^- --> Na⁺

Mg – 2e^- --> Mg²⁺

ü  The non metal atom accepts electron/s and it is reduced to form an anion (negative ion).

Reduction:

Cl₂ + 2e^{-   -->}  2Cl^-

O₂ + 4e^- --> 2O^2-

Formation of Electrovalent (Ionic) Compounds:

Example 1 Sodium chloride ( NaCl):

Sodium is a metal with electronic configuration 2,8,1 – has one valence electron.

Chlorine is a non metal with electronic configuration 2,8,7 – has 7 valence electrons.

Sodium has to lose one electron from its valence shell to attain the electronic configuration of its nearest noble gas (Neon) i.e. 2, 8.

Chlorine has gain one electron for the electronic configuration of its nearest noble gas (Argon) i.e 2,8,8

Hence Sodium loses its one electron from the valence shell to the chlorine atom.

Representation of Sodium Chloride using electron dot structures

formation of Sodium chloride

Example 2    Magnesium Oxide (MgO)

Mg – electronic configuration is 2, 8, 2- it loses 2 electrons

O – electronic configuration is 2,6 – it has to gain two electrons.

One Magnesium atom donates two electrons to the Oxygen atom.

formation of Magnesium oxide

Example 3 Magnesium Chloride (MgCl₂)

Mg – 2,8,2 – Mg atom has to lose 2 electrons and

Cl – 2,8,7 – each Chlorine atom requires one more electron to get the stable electronic configuration.

Hence Mg atom donates one electron to each chlorine atom.

formation of Magnesium chloride