What is the formula for magnesium chloride?

The formula for magnesium chloride is MgCl₂. This reflects that one magnesium ion (Mg²⁺) combines with two chloride ions (Cl⁻) to form a neutral compound. Magnesium has a valency of +2, indicating it loses two electrons when it forms an ion. Chloride, on the other hand, has a valency of -1, meaning each chloride ion gains one electron.

To achieve electrical neutrality in the compound, one magnesium ion must bond with two chloride ions, thus leading to the formula MgCl₂. This concept is grounded in the principle of charge balance in ionic compounds, where the total positive charge from cations must equal the total negative charge from anions.

In contrast, other options do not reflect the correct stoichiometry needed to balance the charges of magnesium and chloride ions. Such misrepresentations fail to reflect the actual composition of magnesium chloride as observed in practical scenarios.