A chemical bond which is formed due to sharing of electrons between two atoms is called “Covalent Bond”.
When the formation of electron is not possible between two atoms, sharing of electrons takes place. So that atoms can manage a complete valence shell. When two atoms shared one or more electrons, then this shared pair of electrons most of the time remains in between two nuclei. Due to this reason attractive forces are developed in between negatively charged electrons and positively charged nuclei which cause the formation of covalent bond.
Types of Covalent Bond
1. Single Covalent Bond:
When one electron pair is shared between two atoms then the covalent bond formed is called “Single Covalent Bond” , denoted by (-).
In case of chlorine molecule (Cl2), each chlorine atom has 7 valence electrons.
So that one electron pair is shared between both atoms so that stable Cl2 molecule is formed as
2. Double Covalent Bond:
When two electron pairs are shared between two atoms then the covalent bond is formed is called “Double Covalent Bond”, denoted by (=).
In case O2 molecule, both oxygen atoms have 6 valence electrons therefore, 2 electron pairs are shared between them to form double covalent bond and stable O2 is formed.
3. Triple Covalent Bond:
A covalent bond formed due to sharing of three electron pairs between two atoms is called “Triple covalent bond”, denoted by ( E ).
In case of N2 molecule, both nitrogen atoms have 5 valence electrons. So that 3 electron pairs are shared between both atoms and triple covalent bond is formed as.