Question

The structure of beryllium chloride in the solid-state and vapor phase, respectively, are:

• A. dimeric and dimeric
• B. dimeric and chain
• C. chain and dimeric
• D. chain and chain

Answer 1

The correct option is C

chain and dimeric

Explanation:

• Beryllium chloride$\left({\mathrm{BeCl}}_2\right)$ is a colorless inorganic solid which can be dissolved in many polar solvents.
• According to Valence bond theory, Beryllium has 2 valence electrons, and thus Beryllium chloride has linear geometry in which the Be atom is $\mathrm{sp}$-hybridized.
• But, Beryllium tends to form different structures in the solid and vapor phase to fulfill the number of electrons required to complete its octet.
• In the vapor phase, it exists as a dimer in which two electrons from the beryllium valence bond form covalent bonds with two chlorine atoms. But then two orbitals in beryllium remain unoccupied, hence called an electron-deficient compound, which can be shown as;

• In its solid-state, beryllium tends to build a polymeric chain in which two electrons in the valence bond of beryllium form covalent bonds with two chlorine atoms.
• But as the two orbitals in beryllium remain unoccupied. So, it forms a coordinate covalent bond with another two chlorine atoms which forms a bridge-like polymeric structure, which can be shown as;

Therefore, option (C) is the correct answer. The structure of beryllium chloride in the solid-state and vapor phase, respectively, are chain and dimeric.