Here's a breakdown:

* Boron (B): A metalloid element

* Fluorine (F): A halogen element

* Three (3): Indicates that there are three fluorine atoms bonded to one boron atom.

Boron trifluoride is a colorless, toxic gas with a pungent odor. It's used in various applications, including:

* Organic chemistry: As a Lewis acid catalyst

* Semiconductor industry: In the etching process

* Refrigerant: In the past, it was used as a refrigerant, but this practice is now largely discontinued due to its toxicity.