What is an Ionic Bond?

Ionic bond can be defined as the chemical bond that involves the electrostatic attraction between charged ions which are opposite to each other and occurs between two atoms with different electronegativities. This occurs in mainly ionic compounds. Ionic bonding is almost as important as covalent or metallic bonding. Ions are basically atoms with some charge. Atoms with electrons make anions which are negatively charged and Cations with positively charged ions. Following are the properties of Ionic Bonding: Cations are metals and Anions are non-metals.

1. An ionic bond occurs when there is electron transfer from metal to a non metal and it becomes one with full valence shell.
2. It is noteworthy to mention that all ionic bonds are not completely clean or pure – they always have traces of covalent or electron sharing.
3. These ionic compounds do conduct electricity and in the state of being molten and when not solid and have high melting points which depends on the ion charge and the higher the charges the stronger the cohesive forces and higher melting points. They tend to be soluble in water and if they have strong cohesive forces the lower is the solubility.
4. The ionic bond in which there is electronegativity difference between the atoms it causes the polar bond between the atoms which is ionic and covalent bonding where electrons are shared equally.

Formation of Ionic Bonding:

It forms in the following way-

1. From Redox reactions where atoms of element which is usually a metal and energy is low and they give off some electrons to basically get more stable configuration. Here cations are formed. In the same way a non metal with electron affinity will accept more electrons to get more stable configuration and thus become an anion.
2. Now we have electrostatic attraction between them will lead to become a solid with a crystal lattice structure and ions are stacked here alternatively. Here the molecular units are not seen properly but the ions here are complex and form molecular ions like acetate anions or cations.
3. Example – Sodium Chloride or Common Salt. Here we have Na and Cl combines and the sodium atoms each lose an electron forming NA+ and Chlorine atoms will get electrons to form Cl- . These ions are attracted to each other in the ratio of 1:1 nd they form Nacl.
4. However now it is important to maintain neutrality the anions and cations are in the same ration and thus maintain stoichiometry but are not molecular. Compounds which are not transitional and have mixed both ionic and metallic bonding it is not true any more. They do not form non- stoichiometric compounds.
5. Many ionic compounds are referred as Salts as they can also be formed by the neutralisation forces of the reaction. Here if we see NaCl have both Cl- acid and base that is Na+.
6. Ionic bonding will only occur if the energy change is favourable in the situation. It is exothermic and charge of the ions is the strength of ionic bonding.

Strength of the ionic bonding:

Here let us consider a solid crystal which has ionic compounds undergoing enthalpy change and it forms the solid from gas ions and the the change is called as Enthalpy energy. The energy here is the sum of the potential energy obtained by adding the interactions between the cations and anions.

Comparison with covalent bonding:

1. In Ionic Bonding: There are attractions between the oppositely charged ions but in Covalent bonding there is no attraction but only sharing of electrons to get configuration.
2. Ionic Bonding – Maximum rules of packing whereas in /covalent bonding there is valance shell electron pair geometry
3. In Ionic Bonding there the ions are in higher coordination number but not in case of Covalent bonding.

The Polarising effects of Ionic Compounds:

The ions are spherical for crystals and if the positive ion is very small and charged then the electron cloud will distort and it will again disturb the negative ion cloud and thus en effect will continue. This polarisation of the negative ion will lead to extra charge density between the uncle and also impart covalence to a degree.  Large ions with negative charge can be easily polarised and the effect is important when the positive ions have charges of 3+. Some ions with less charges like Lithium with 1+ show power of polarisation because the sizes are small and this is not ionic polarisation effect but it is ion displacement due to electric field power.