When element X with an atomic number of 19 (which corresponds to potassium, symbol K) reacts with element Y with an atomic number of 17 (which corresponds to chlorine, symbol Cl), they form an ionic compound called potassium chloride (KCl).
Potassium chloride is a white crystalline solid that is highly soluble in water. It is commonly used as a dietary supplement, a salt substitute, and in the production of fertilizers and other chemicals.