Here's why:

* Conductivity: While bismuth does conduct electricity, it's not as good a conductor as metals like copper or silver. Its conductivity is much lower than typical metals.

* Energy Gap: Bismuth has a small band gap, which is a characteristic of semiconductors. The band gap is the energy difference between the valence band and the conduction band. In semiconductors, this gap is small enough that electrons can be excited into the conduction band with relatively low amounts of energy, allowing for electrical conductivity.

Important Note: The classification of materials as semiconductors, conductors, or insulators can be a bit fuzzy. Bismuth's behavior is often described as "semimetallic" due to its unique properties.