Difference Between Covalent and Ionic Bonds

Main Difference – Covalent vs Ionic Bonds

It is the nature of elements to form bonds between them in order to become stable. Covalent bonds and ionic bonds are two different ways of how elements bond to each other. The main difference between covalent and ionic bonds is that ionic bonds occur between two species which are electrostatically attracted towards each other, whereas covalent bonds occur covalently through the sharing of electrons between their outer shells. In general, metallic elements tend to form ionic bonds, and non-metallic elements tend to form covalent bonds.

What is an Ionic Bond | How Ionic Bond is Formed | Properties of Ionic Bonds

As mentioned above, ionic bonds are a result of electrostatic forces between atoms that get attracted towards each other due to the possession of opposite electrical charges. Each element tries to accomplish a stable electronic configuration at the outer shell (electronic configuration of the noble gases). Having a noble gas electronic configuration prevents atoms from further reactions as they are already stable. Therefore, elements in nature which are not electronically stable, tend to give away any extra electrons or to accept the missing number of electrons in order to achieve the closest noble gas configuration. Ions are formed under this principle.

Atoms which tend to give away their extra electrons to attain stable electronic configuration end up being positively charged (due to the loss of negatively charged electrons) and these are called “cations”. Similarly, when an atom accepts electrons to complete the final shell configuration they become negatively charged (due to the increase in negatively charged electrons) and these are called “anions”. Therefore by definition, ionic bonds are formed between anions and cations.

Ionic compounds tend to be solid in nature, and they usually have very high melting points as the ionic bonds are quite strong; in fact it is the strongest type of chemical bond that exists. Ions can be atomic or molecular in nature. i.e. CO₃^2-is a molecular anion. Few examples of ionic compounds are NaCl, MgCl_2, etc.

What is a Covalent Bond | How Covalent Bond is Formed | Properties of Covalent Bonds

Covalent bonds are much weaker than the ionic bonds and, therefore, most of the covalent compounds exist in the gaseous phase. As mentioned above, the atoms need to form electrons in order to attain a stable electronic configuration. The third way of obtaining this (apart from giving away and accepting electrons as mentioned in the case of the ionic bonds) is through the sharing of electrons.

In this method, both atoms taking part in the formation of the compound get to share the required number of electrons (usually with one donor atom and an acceptor atom looking for the same amount of electrons) in a common overlapped orbital space. It is important that the atoms come into close proximity of each other for the orbital overlap before the electron sharing takes place. Therefore, in this case, neither atom will be electrically charged but will remain neutral. The overlapping can take place in linear fashion or in a parallel manner. When it is directed and linear, the bond type is called a “σ bond” and in the other case, it is a “π bond”. Furthermore, this sharing of electrons can take place between similar type of atoms as well as different types of atoms. When the involved atoms are similar, the resulting compound is called a ‘diatomic molecule’. H₂O, CO_2, etc. are some common examples.