Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a heavy, brittle metal that is often found in nature as a byproduct of mining other metals like lead and copper. Bismuth has a low toxicity compared to other heavy metals, making it useful in various applications, including cosmetics and pharmaceuticals. In its pure form, bismuth has a silvery-white appearance with a slight pink hue. It is known for its unique properties, such as low thermal conductivity and high density. Bismuth also expands when it solidifies, which is unusual for metals, and it is often used in alloys and as a replacement for lead in certain applications.