Explain the reasons why chloride ions (Cl-) is detrimental to corrosion of various metals. Solution Corrosion of metals can be defined as the degradation of quality or quantity of metals by the attacking of atmospheric gases or other radicals to form unwanted products. From the difinition metallic nature, metals have a tendency to lose electrons and become positively charged ions at the surface level and these positive charged species attracts negative chloride ions and undergo reaction to form undesired metal chlorides. M ----------> M+ + e- M+ + Cl- -----------> metal chloride ( undesired product ) Chloride ion being highly reactive it can react with various metals and so its is detrimental to corrosion of various metals. .