Silicon nitride is a chemical compound of the elements silicon and nitrogen, with the formula Si 3N 4. It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H 2SO 4. It is the most thermodynamically stable of the silicon nitrides. Hence, Si 3N 4 is the most commercially important of the silicon nitrides and is generally understood as what is being referred to where the term "silicon nitride" is used.