Final answer:
Chromium is the transition metal that when added to iron, produces bright, shiny steel used in car bumpers and faucets.
Step-by-step explanation:
The transition metal that is added to iron to create a bright, shiny steel commonly used in car bumpers and faucets is Chromium. This metal is known for its high shine and resistance to tarnishing, which makes it an excellent choice for creating a protective and aesthetically pleasing surface on steel products. Chromium plating is used in various applications, such as automotive detailing and the protective plating on plumbing fixtures, to enhance both the appearance and durability of steel.