Introduction:
Ionic and covalent bonds are two types of chemical bonds that form between atoms. The nature of the bond depends on the electronegativity difference between the atoms involved. In the case of NaCl and LiCl, they have different bonding types due to variations in the electronegativity of the elements.

Electronegativity and Bonding:
Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. When the electronegativity difference between two atoms is large, an ionic bond is formed. Conversely, when the electronegativity difference is small, a covalent bond is formed.

Electronegativity of Sodium (Na) and Chlorine (Cl):
Sodium (Na) has an electronegativity value of 0.93, while chlorine (Cl) has an electronegativity value of 3.16. The electronegativity difference between them is 2.23.

NaCl - Ionic Bond:
Ionic bonds occur when there is a large electronegativity difference between the atoms involved. In the case of NaCl, sodium has a lower electronegativity compared to chlorine. Sodium readily donates its valence electron to chlorine, resulting in the formation of Na+ and Cl- ions. These oppositely charged ions are attracted to each other, forming an ionic bond.

Electronegativity of Lithium (Li) and Chlorine (Cl):
Lithium (Li) has an electronegativity value of 0.98, while chlorine (Cl) has an electronegativity value of 3.16. The electronegativity difference between them is 2.18.

LiCl - Covalent Bond:
Covalent bonds occur when there is a small electronegativity difference between the atoms involved. In the case of LiCl, the electronegativity difference between lithium and chlorine is relatively small. The two atoms share their valence electrons to achieve a stable electron configuration. This sharing of electrons forms a covalent bond.

Conclusion:
In summary, NaCl is an ionic compound because of the large electronegativity difference between sodium and chlorine. Sodium donates its electron to chlorine, resulting in the formation of oppositely charged ions. On the other hand, LiCl is a covalent compound due to the relatively small electronegativity difference between lithium and chlorine. They share electrons to form a stable bond. Understanding the electronegativity difference between elements helps determine the type of bond formed between them.