Do you know why some compounds show strong conductivity, while some are pretty slow at it? If you were to melt such substances, you will find that they have a sharp melting point. Why does it happen? These substances are Ionic or Electrovalent compounds. In this chapter, we will have a closer look at these ionic or electrovalent compounds. Let’s begin.
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Ionic or Electrovalent Bond
There are primarily three ways in which two atoms combine together to lose energy and to become stable. One of the ways is by donating or accepting electrons so as to complete their octet configuration. The bond formed by this kind of combination is an ionic bond or electrovalent bond.
An Ionic bond is the bond formed by the complete transfer of valence electron so as to attain stability. This type of bonding leads to the formation of two oppositely charged ions. These include the positive ion, cations and negative ions, anions. The presence of two oppositely charged ions results in strong attractive force between them. This force is the ionic or electrovalent bond.
Properties of an Ionic Bond
Due to the presence of a strong force of attraction between cations and anions in ionic bonded molecules, we observe the following properties:
- The ionic bonds are the strongest of all the bonds.
- The ionic bonds have a charge separation. So, they are the most reactive of all the bonds in the proper medium.
- The ionic bonded molecules have high melting and boiling point.
- The ionic bonded molecules in their aqueous solutions or in the molten state are good conductors of electricity. This is due to the presence of ions which acts as charge carriers.
Examples of Ionic Bonds
The following table shows the elements and the ions formed by them when they lose or gain an e‑.
| Element | Electronic config. | Reaction | Formed ion |
| Na(11) | 2,8,1 | Na → Na+ + e–  …………………Reaction 1 | Na+ |
| Ca(20) | 2,8,8,2 | Ca → Ca2+ + 2e–……………….. Reaction 2 | Ca2+ |
| Cl(17) | 2,8,7 | Cl + e–→ Cl– ………………….…. Reaction 3 | Cl– |
| O(8) | 2,6 | O + 2e–→ O2-……………………..Reaction 4 | O2- |
Now, when Na reacts with Cl, reaction 1 and reaction 3 will take place. The resultant compound will be NaCl. When Na reacts with O, reaction 1 and reaction 4 will take place. The resultant compound will be Na2. In the case when Ca reacts with Cl, reaction 2 and reaction 3 will take place. The resultant compound will be CaCl2.
When Ca reacts with O, reaction 2 and reaction 4 will take place and the resultant compound will be CaO. We, now have some information about ionic or electrovalent bonds. Let us now look at what electrovalent compounds are and what their characteristics are.
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Electrovalent Compounds
The compounds which contain ionic or electrovalent bonds are Electrovalent or Ionic Compounds. Mainly electrovalent compounds are formed due to the reaction between highly electropositive and highly electronegative atoms.
Characteristics of Electrovalent Compounds
- Crystal Structure: In the solid state of electrovalent compounds, anions and cations are arranged in a regular manner. This is a crystal in which anions are surrounded by a definite number of cations and vice-versa.
- Physical Nature: Ionic or electrovalent compounds are generally hard. Their hardness increases with increasing ionic charge and the decreasing distance between ions.
- Solubility: Positive ion of ionic compound attaches to the negative part of a polar solvent and negative ion of ionic compound attach with the positive part of the polar solvent. Therefore, ionic or electrovalent compounds are soluble in polar solvents like water and insoluble in non-polar solvents like benzene, ether, alcohol.
- Melting Point and Boiling Point: Electrovalent or ionic compounds have high melting and boiling points because they need a large amount of energy to break strong ionic bonds.
Solved Example for You
Q: The state in which HCl is a bad conductor of electricity is _________ but, the state in which HCl is a good conductor of electricity is __________ .
A) Solid, Anhydrous     B) Aqueous, Solid     C) Anhydrous, Solid       D) Anhydrous, Aqueous
Solution: D) Well any substance that can give rise to ions inside a solution or has free charges within itself is a conductor. As anhydrous HCl doesn’t have any free ions or charges, it will not conduct. While on the other hand, Aqueous HCl has Hydrogen and Chloride ions present in the solution, so it will conduct electricity.
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