Ionic bonding in calcium chloride

Steps:

• Identify calcium chloride (CaCl₂) as an ionic compound formed from metal calcium and non-metal chlorine.
• Recall that ionic compounds consist of positive and negative ions held by electrostatic forces.
• Determine the structure: ions arrange in a regular, repeating 3D lattice to maximize stability.
• Evaluate properties: lattice explains high melting point, insolubility or solubility, and conductivity.

Why C is correct:

• Ionic compounds like CaCl₂ form giant ionic lattices of alternating Ca²⁺ and Cl⁻ ions, as defined by ionic bonding theory.

Why the others are wrong:

• A: Solid ionic compounds do not conduct electricity due to fixed ions unable to move.
• B: Ionic lattices require high energy to break, resulting in a high melting point (around 772°C for CaCl₂).
• D: CaCl₂ is soluble in water, as polar water molecules hydrate and separate the ions.

Final answer: C