Bromine
Element 35 · Halogen
Bromine is a dense, red-brown liquid — one of only two elements liquid at room temperature, and the only nonmetal among them. It fumes readily, releasing corrosive orange vapors that attack eyes, lungs, and skin, so it is handled only in fume hoods.
As a halogen in group 17, bromine is a vigorous oxidizer: it bleaches, disinfects, and reacts with metals to form bromide salts, though it is less aggressive than chlorine or fluorine. Silver bromide's sensitivity to light made it the foundation of traditional photography.
Key facts
| Atomic number | 35 |
|---|---|
| Atomic weight | 79.904 |
| Category | Halogen |
| Group / Period | 17 / 4 |
| Block | p |
| Electron configuration | [Ar] 3d10 4s2 4p5 |
| Common oxidation states | -1, +1, +5 |
| State at STP | Liquid |
| Electronegativity | 2.96 |
| Atomic radius | 94 pm |
| Density | 3.12 g/cm³ |
| Melting point | -7.2 °C |
| Boiling point | 58.8 °C |
Occurrence
Bromine never occurs free in nature; it is extracted from seawater and underground brine wells, where it exists as dissolved bromide salts. The Dead Sea and Arkansas brines are major sources. Its name comes from the Greek bromos, meaning stench, for its sharp, choking odor.
Applications
Flame retardants in furniture and electronics use brominated compounds
Photographic film and paper rely on light-sensitive silver bromide
Water treatment and hot tubs use bromine as a disinfectant
Pharmaceuticals and dyes incorporate bromine in their synthesis
Agricultural fumigants historically used bromine compounds
Common compounds
- sodium bromide
- hydrogen bromide
- silver bromide
- bromine trifluoride
Bromine is the only nonmetal that is liquid at room temperature — and it evaporates into choking red fumes.
Data source: IUPAC standard atomic weights 2021