Halogen (noun)

A chemical element of the halogen group with the atomic number 17, occurring naturally as fluorine, chlorine, bromine, and iodine.

Origin:

From the greek words hals (salt) and gennan (to produce).

Examples:

1. The halogens are the most reactive of all the elements.
2. Chlorine is the most abundant halogen.
3. Bromine is commonly used as a flame retardant.
4. Fluorine is the most reactive of the halogens and is used in the production of uranium hexafluoride.
5. Iodine is a necessary trace element for the human body, and is commonly found in iodized salt.