Reason for Lithium having greater tendency to form covalent compound than other elements in the group

There are a few reasons why lithium has a greater tendency to form covalent compounds compared to other elements in its group.

Size of Lithium Atom

The size of the lithium atom is relatively small compared to other elements in its group. This small size means that the attraction between the positively charged nucleus and the negatively charged electrons is relatively strong. As a result, the lithium atom can easily form covalent bonds with other atoms.

Electronegativity of Lithium

Lithium also has a low electronegativity compared to other elements in its group. Electronegativity is a measure of an atom's ability to attract electrons towards itself. Atoms with a low electronegativity are less likely to attract electrons and more likely to form covalent bonds.

Valence Electrons of Lithium

Lithium has only one valence electron. This means that it can easily lose this electron to form a positive ion or share it with another atom to form a covalent bond. Other elements in its group have more valence electrons, which makes it more difficult for them to form covalent bonds.

Conclusion

In conclusion, the small size of the lithium atom, its low electronegativity, and its valence electron configuration all contribute to its greater tendency to form covalent compounds compared to other elements in its group.

Covalent compounds are usually formed by cations of smaller size and anions having larger size...as lithium has effectively smaller size as compared to others it has a greater tendency to form covalent compounds...you can also refer fajan's rules