Bismuth is a post-transition metal that is commonly used in alloys to improve their mechanical properties. It has the highest atomic mass of the stable elements and is relatively non-toxic compared to other heavy metals. Bismuth’s unique properties, such as its expansion upon solidification and diamagnetic behavior, make it useful in a variety of applications such as fire sprinkler systems, cosmetics, and medical imaging. It also has potential as a replacement for lead in certain applications due to its low toxicity and similar properties.