Which element is a halogen with atomic number 35?

The halogen with atomic number 35 is bromine.

Bromine is the chemical element with the symbol Br and atomic number 35, meaning each neutral bromine atom contains 35 protons. It occupies group 17 of the periodic table, the halogen group, alongside fluorine, chlorine, iodine, and astatine. Halogens characteristically have seven valence electrons and tend to gain one electron when forming halide ions.

At room temperature, bromine is a volatile red-brown liquid, unusual among the common elemental halogens: fluorine and chlorine are gases, while iodine is a solid. Bromine’s properties fall broadly between those of chlorine and iodine. Its elemental molecules are diatomic, written Br₂.

Carl Jacob Löwig isolated bromine in 1825, and Antoine Jérôme Balard independently identified it in 1826. The name comes from Greek bromos, meaning “stench,” referring to its sharp odor. Bromine is not usually found free in nature because it is reactive; bromide salts accumulate in seawater, salt lakes, and brines. Chlorine is more reactive than bromine, while iodine is less reactive.