Chemical Bonding is the phenomenon in which two atoms combine together and results into formation of molecule or compound.
Cause of Chemical Combination
Atoms combine with one another due to inherent tendency to stabilize themselves. They achieve their stabilization by losing, gaining or sharing of electrons to attain the nearest noble gas configuration. The tendency of an atom to attain maximum of eight electrons in the valence shell is called as octet rule.
Types of Chemical Bonding
There are two types of chemical bonding: inter-atomic and inter molecular bonding. Inter atomic bonding further classified into ionic, covalent, coordinate covalent and metallic bonding. Intermolecular bonding classified into Vander Waals, hydrogen bonding etc. Here we would discuss the inter-atomic bonding, in which two atoms combine together to form a compound.
An ionic bond forms when atoms participate in bond formation involve transfer of electrons from one atom to other and form ions. The electrostatic force of attraction plays an important role to hold these oppositely charged ions close to results in the formation of strong ionic bond. The ionic bond forms between atoms which have greater difference in their electronegativities.
The covalent bond forms by mutual sharing of electrons by two atoms. The atoms which participate to form covalent bond have same or small difference in the electronegativities. The covalent bond is represented by dash ( – ) between two atoms. The covalent bond can be formed as single, double and triple bonds. There are two types of covalent bonds on the basis of polarity.
Non-Polar Covalent Bond
The bond formations of atoms by mutual sharing and have same electronegativities is called as non-polar covalent bond. For example: H2, Cl2, O2, N2, and CH4 etc.
Polar Covalent Bond
The bond formations of atoms by mutual sharing and there is small difference in electronegativities of the atoms is called as polar covalent bond. For example: H2O, HCl, NH3 etc. In this type, bonding pair would shift to the more electronegative atom and forms the partial positive and partial negative charges on the atoms.
Here, we can observe in the above example that Hydrogen is less electronegative atom and Chlorine is more electronegative atom. The Cl attracts the bonding pair because it is more electronegative atom and it possesses partial negative charge whereas H acquires partial positive charge.
Coordinate Covalent Bond
A coordinate covalent bond forms between two atoms when the shared pair of electrons donates one of the bonded atoms.
Example: Bond between NH3 and BF3.
NH3 has three covalent bonds and there is one lone pair of electrons on nitrogen atom. On the other hand, Boron atom in BF3 is deficient in electrons. Actually the octet of the boron is not complete in BF3. Therefore, nitrogen can donate the pair of electrons to the acceptor BF3 and this result in the formation of a coordinate covalent bond.
The complex produced is overall neutral, and charges indicated on N and B atoms.
A bond which is formed between positively charged atoms in which free electrons shared among a lattice of electrons. It is main type of bonding which occurs between the metals. Metallic bonds can be observed in pure metals, alloys and some metalloids.
For example: Graphene which an allotrope of carbon, can form two dimensional metallic bonding.