Here's how it breaks down:

* NH₄⁺: This represents the ammonium ion, which is a positively charged ion formed by the combination of ammonia (NH₃) and a hydrogen ion (H⁺).

* CO₃²⁻: This represents the carbonate ion, which is a negatively charged ion composed of one carbon atom and three oxygen atoms.

Since ammonium has a +1 charge and carbonate has a -2 charge, you need two ammonium ions to balance the charge of one carbonate ion, hence the (NH₄)₂ part of the formula.