H3O⁺ represents a hydronium ion—an aqueous cation formed when an acidic proton (H+) attaches itself to a water molecule (H2O).
This term refers to the hydroxide ion—an aqueous anion formed when a water molecule loses a proton (H+).
This term represents a hydrogen ion—a lone proton without any electrons.
NH4⁺: This term stands for ammonium ion, which forms when ammonia (NH3) gains a hydrogen ion (H+).