Question

The structures of beryllium chloride in solid state and vapor phase, are

• A. Chain in both
• B. Chain and dimer, respectively
• C. Linear in both
• D. Dimer and Linear, respectively

Answer 1

The Correct Option is B

To understand the structures of beryllium chloride in different states, we need to analyze its behavior in both the solid state and vapor phase.

1. Solid State: In the solid state, beryllium chloride (BeCl_2) forms a polymeric chain structure. This is due to the small size and high charge density of beryllium ions, which leads to covalent bonding and the formation of extended chains. Each beryllium atom is tetrahedrally coordinated by four chlorine atoms, two of which are shared with adjacent beryllium atoms, resulting in a chain-like structure.
2. Vapor Phase: In the vapor phase, beryllium chloride exists as discrete dimeric molecules rather than long chains. This dimeric form is typically (Be_2Cl_4), where two beryllium atoms are bridged by two chlorine atoms, forming a cyclic structure. This transformation from chain to dimer occurs because the energy required to break the chains is offset by the formation of stable Be-Cl bonds in the dimeric form.

Therefore, the correct answer is that beryllium chloride forms a chain structure in the solid state and exists as a dimer in the vapor phase. The correct choice as per the options provided is "Chain and dimer, respectively".