Here's why:

* H⁺: This is the hydrogen ion, a single proton.

* CO₃⁻²: This is the carbonate ion, a polyatomic ion with one carbon atom and three oxygen atoms, carrying a -2 charge.

To form a neutral compound, one hydrogen ion (H⁺) combines with one carbonate ion (CO₃⁻²), resulting in the formula HCO₃⁻.

While the formula is often written as HCO₃⁻, the name "hydrogen carbonate" or "bicarbonate" is used to emphasize the presence of the carbonate ion.