cadmio

Cadmio, known in English as cadmium, is the chemical element with symbol Cd and atomic number 48. It is a soft, bluish-white metal in group 12 of the periodic table. Cadmium is relatively resistant to corrosion in dry air but can form oxides and sulfides when exposed to moisture and air.

Cadmium occurs primarily as a byproduct of zinc and lead ore processing and is recovered during refining of zinc sulfide minerals such as sphalerite. Global production is closely tied to zinc mining and refining activities. Cadmium has a lower melting point than many other metals, approximately 321°C, and a density of about 8.65 g/cm3. It forms a wide range of compounds, notably cadmium sulfide (CdS), used as a yellow pigment, and cadmium oxide (CdO). Cadmium is used in nickel–cadmium batteries, cadmium plating for corrosion resistance, pigments, and certain solar and electronic materials (for example, cadmium telluride in thin‑film photovoltaics).

Health and environmental effects: Cadmium and cadmium compounds are highly toxic. Chronic exposure can damage kidneys and bones; the disease Itai‑itai, linked to cadmium-contaminated food, highlighted the risk. Cadmium persists in soil and water and bioaccumulates in organisms. Due to these risks, many countries regulate cadmium use, emissions, and waste. Recycling of cadmium-containing devices, proper handling in industry, and safe disposal are important.

History: Cadmium was discovered in 1817 by Friedrich Stromeyer. The name derives from Latin cadmia, referring to calamine or zinc oxide minerals from which it was first isolated.