a compound consisting of ions (charged particles)
As all compounds are electrically neutral,
the total charge on the cations equals the total charge on the anions.

The charge on the ions is not shown in its formula

sodium chloride, NaCl,
sodium ions, (Na⁺), and chloride ions, (Cl⁻)

sodium sulfate, Na₂SO₄,
sodium ions, (Na⁺) and sulfate ions, (SO₄²⁻);

ammonium sulfate, (NH₄)₂SO₄,
ammonium ions, (NH₄⁺), and sulfate ions, (SO₄²⁻);

sodium silicate, (Na₂SiO₃),
Na⁺ cations and polymeric (SiO₃²⁻)_x anions.