Phosphorus pentoxide, P₄O₁₀, is an ionic compound, meaning that it consists of positively and negatively charged ions. In phosphorus pentoxide, the phosphorus atoms are in the +5 oxidation state, while the oxygen atoms are in the -2 oxidation state. This means that each phosphorus atom is bonded to five oxygen atoms, and each oxygen atom is bonded to two phosphorus atoms. The resulting compound is a white, crystalline solid that is soluble in water.