Balanced chemical reaction:
Pb(NO₃)₂(aq) + K₂SO₄(aq) → PbSO₄(s) + 2KNO₃(aq).
Ionic reaction:
Pb²⁺(aq) + 2NO₃⁻(aq) + 2K⁺(aq) + SO₄²⁻(aq) → PbSO₄(s) + 2K⁺(aq) + 2NO₃⁻(aq).
Net ionic reaction:
Pb²⁺(aq) + SO₄²⁻(aq) → PbSO₄(s).
(s) means solid (not dissolved in water).
According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.