platinum group metals; platinum group elements
Technical term in chemistry and materials science referring to the six noble metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum.
Platinum group elements are chemically stable and widely used as catalysts.
白金 (platinum) is one specific element; 白金族元素 refers to the entire group of platinum-group metals.
Compound of 白金 (platinum) + 族 (group) + 元素 (element). The term is a direct calque from English 'platinum group elements'.