What are the physical states of halogens at room temperature?

At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids.

Halogens are a group of elements in the Periodic Table, specifically Group 7. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Each of these elements has different physical states at room temperature, which is typically considered to be around 20-25 degrees Celsius.

Fluorine and chlorine are both gases at room temperature. Fluorine is a pale yellow gas, while chlorine is a greenish-yellow gas. Both are highly reactive, with fluorine being the most reactive of all elements. They can react with many other elements and compounds, often in a vigorous or even explosive manner.

Bromine is unique among the halogens, and indeed rare among all elements, in being a liquid at room temperature. It is a reddish-brown liquid, which gives off a similarly coloured vapour. Bromine is less reactive than fluorine and chlorine, but still quite reactive and can be harmful or lethal to living organisms in large amounts.

Iodine and astatine, the heavier halogens, are solids at room temperature. Iodine forms dark grey, shiny crystals and gives off a purple vapour when heated. It is less reactive than the lighter halogens, but can still form compounds with many elements. Astatine is a radioactive element and is usually represented as a black solid, although very little is known about it due to its extreme rarity and radioactivity.

In summary, the physical states of the halogens at room temperature range from gases (fluorine and chlorine), to a liquid (bromine), to solids (iodine and astatine). This is a reflection of their increasing atomic masses and the corresponding changes in intermolecular forces.