Covalent nature of compounds

Compounds are of two types based on their nature: covalent and ionic. Covalent compounds are formed by the sharing of electrons between atoms, whereas ionic compounds are formed by the transfer of electrons from one atom to another. The type of bond formed between atoms in a compound determines its nature.

Essentially covalent compound

An essentially covalent compound is a compound that has a high degree of covalent character. In other words, the sharing of electrons between atoms is so strong that the compound behaves as if it were a purely covalent compound. Essentially covalent compounds usually have low melting and boiling points, and they are poor conductors of electricity.

BeCl2 as an essentially covalent compound

Out of the given options, the compound that is essentially covalent in nature is BeCl2. Beryllium chloride (BeCl2) is a linear molecule in which the two chlorine atoms share their electrons with the beryllium atom. The electronegativity difference between beryllium and chlorine is small, which means that the sharing of electrons is almost equal. This results in a high degree of covalent character in the Be-Cl bond, making BeCl2 an essentially covalent compound.

On the other hand, CaCl2, SrCl2, and MgCl2 are ionic compounds. In these compounds, the electronegativity difference between the metal and the halogen is large, resulting in the transfer of electrons from the metal to the halogen. As a result, these compounds have a high degree of ionic character.

Conclusion

In conclusion, BeCl2 is an essentially covalent compound, while CaCl2, SrCl2, and MgCl2 are ionic compounds. The nature of a compound is determined by the type of bond formed between atoms, which is in turn determined by the electronegativity difference between the atoms.