Britannica Sources used in this answer

Why is bromine unusual among the chemical elements at room temperature?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — halogen Modern version of the periodic table of the elements.

Bromine is considered unusual among the chemical elements because it is one of only two elements that exist as a liquid at room temperature (20 °C or 68 °F) and atmospheric pressure, the other being mercury.1

Within the halogen group, this state is distinct: fluorine and chlorine are gases at room temperature, while iodine exists as a solid. As a member of the halogen family, bromine is a reddish-brown, volatile liquid with an appreciable vapor pressure at room temperature.12