He Fig . Lewis Structures of He atom Octet rule The idea of Kossel – Lewis approach to chemical bond lead to the octet rule, which states that “ the atoms transfer or share electrons so that all atoms involved in chemical bonding obtain electrons in their outer shell (valence shell) ”. . Types of chemical bonds The chemical bonds can be classified based on the nature of the interaction between the bonded atoms.
Two major types of chemical bonds are covalent bonds and ionic bonds. Generally metals reacts with non-metals to form ionic compounds, and the covalent bonds are present in the compounds formed by nonmetals. . .
Covalent bonds: Do you know all elements (except noble gases) occurs either as compounds or as polyatomic molecules? Let us consider hydrogen gas in which two hydrogen atoms bind to give a dihydrogen molecule. Each hydrogen atom has one electron and it requires one more electron to attain the electronic configuration of the nearest noble gas helium. Lewis suggested that both hydrogen atoms will attain the stable configuration by mutually sharing the electrons available with them.
Similarly, in the case of oxygen molecule, both the oxygen atoms share two electron pairs between them and in nitrogen molecule three electron pairs are shared between two nitrogen atoms. This type of mutual sharing of one or more pairs of electrons between two combining atoms results in the formation of a chemical bond called a covalent bond . If two atoms share just one pair of electron a single covalent bond is formed as in the case of hydrogen molecule. If two or three electron pairs are shared between the two combining atoms, then the covalent bond is called a double bond or a triple bond, respectively.
(H ) Single Covalent Bond (O ) Double Covalent Bond (N ) Triple Covalent Bond Fig . Representation of Lewis Structures of covalent bonds Unit Unit - - - - . . Representing a covalent bond - Lewis structure (Lewis dot structure) Lewis structure (Lewis dot structure)