Final answer:
Magnesium carbonate, with the chemical formula MgCO₃, is the ionic compound formed by the reaction between Mg₂ and CO₃²⁻. This is a simple transfer of electrons where magnesium atoms become positively charged ions, combining with the unchanged carbonate ions.
Step-by-step explanation:
The compound formed by the ionic reaction between Mg₂ and CO₃²⁻ is magnesium carbonate, which has the chemical formula MgCO₃. This is an ionic compound composed of magnesium cations (Mg²⁻) and carbonate anions (CO₃²⁻). The reaction to form this compound involves the transfer of electrons between atoms, similar to how two neutral elements like magnesium (Mg) and chlorine (Cl₂) react to form the ionic compound magnesium chloride (MgCl₂). Here, magnesium atoms lose two electrons to form Mg²⁻ ions, while carbonate ions remain unchanged.
During reactions that form salts, such as the neutralization reaction between hydrochloric acid (HCl) and magnesium hydroxide (Mg(OH)₂), magnesium chloride (MgCl₂) is formed alongside water, which demonstrates the formation of a salt in an acid-base reaction.