Introduction
Let us examine closely the following sets of compounds and study their properties in terms of their physical state, melting points and boiling points.
Need for Bonding
Chemical bonding is like a glue that binds atoms together. And what goes into making that glue? Only electrons. Not all electrons make up the glue, it is only the valence electrons. Valence electrons are the outermost electrons [electrons in the last shell].
Atoms and Ions
Listed below are some elements that attain the octet configuration of Noble gases. Let us see how this happens. Study the given table:
Ionic Compounds
Ionic bond: The electrostatic force of attraction that is strong enough to hold together two unlike charges, namely a cation and an anion is defined as the ionic bond.
Covalent Bonding
Can we imagine a world without oxygen, nitrogen, water or carbon dioxide? Without any of these there would be no life at all. All the above mentioned compounds are covalent compounds formed by sharing of electrons. Non-metal atoms share the valence electrons and form molecules. These shared pairs of electrons contributed by each of the atoms involved in bonding are located between the nuclei of atoms.
Single Covalent Bond
A single bond consists of one pair of shared electrons. In other words, it is formed by sharing one pair of electrons or two electrons between the atoms, each atom contributing one electron to the bond.
Double Covalent Bond
A double covalent bond consists of two pairs of shared electrons. It is formed by the sharing of two pairs of electrons between two atoms. It is actually a combination of two single bonds. It is represented by putting two short lines between the two atoms [=].
Triple Covalent Bond
A triple covalent bonds consists of three pairs of shared electrons. It is formed by the sharing of three pairs of electrons between two atoms. In all there are six electrons shared between two atoms. It is a combination of three single bonds. It is represented by 
(short lines).
Polar and Non-Polar Covalent Bonds
Covalent bonds may be non-polar or polar in nature.
Non-polar molecule of methane
Methane
Properties of Non-Polar and Polar Covalent Compounds
Comparitively stronger forces than Van der Waal's forces exist between molecules.
Coordinate Bond
It is a special type of a covalent bond wherein the shared pair of electrons is supplied by only one of the bonding atoms. A lone pair of electrons is present in one of the atoms.
Characteristics of Covalent Compounds
Covalent compounds consist of molecules and not ions. The molecules do not have any electric charge on them. The molecules are held together by weak forces called Van der Waal's forces.
Mixed Bonding
Apart from coordinate covalent compounds, there are some compounds, which contain both ionic and covalent compounds.
Conclusion
In this chapter on chemical bonding, we have learnt the meaning of chemical bonding, need for bonding, and the different types of chemical bonding: ionic, covalent, polar covalent and coordinate bonding.
