Quick Facts
| Property | Value |
|---|---|
| Symbol | Br |
| Atomic Number | 35 |
| Atomic Mass | 79.904 u |
| Category | Halogen |
| Period | 4 |
| Group | 17 |
| Block | p |
| Electron Configuration | [Ar] 3d¹⁰ 4s² 4p⁵ |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Liquid |
| Density | 3.1028 g/cm³ |
| Melting Point | -7.2°C (265.95 K) |
| Boiling Point | 58.8°C (331.95 K) |
| Appearance | Reddish-brown, fuming liquid |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Ar] 3d¹⁰ 4s² 4p⁵ |
| Electronegativity | 2.96 (Pauling scale) |
| First Ionization Energy | 1139.9 kJ/mol |
| Atomic Radius | 120 pm |
| Covalent Radius | 120 pm |
| Van der Waals Radius | 185 pm |
History and Discovery
Discovered by: Antoine Jérôme Balard and Carl Jacob Löwig Year of Discovery: 1826 Location: Montpellier, France and Heidelberg, Germany
Etymology
The name "bromine" comes from the Greek "bromos" meaning "stench," referring to its strong, unpleasant odor.
Discovery Story
Antoine Jérôme Balard discovered bromine in 1826 while studying seaweed extracts. Carl Jacob Löwig independently discovered it around the same time. Balard published first and is generally credited with the discovery. Justus von Liebig had seen it earlier but mistook it for iodine chloride.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ⁷⁹Br | 50.69% | Stable | - |
| ⁸¹Br | 49.31% | Stable | - |
Occurrence
Natural Abundance
Bromine comprises about 2.4 ppm of Earth's crust but is concentrated in seawater (about 65 ppm) and salt lakes. The Dead Sea has particularly high bromine content. Major producers are the United States, Israel, and China.
Extraction and Production
- Brine Extraction: Chlorine displaces bromine from brine
- Seawater: Some production from ocean water
- Dead Sea: Major commercial source
- Global production: about 550,000 tons annually
Applications and Uses
Flame Retardants
- Brominated flame retardants (largest use)
- Electronics, textiles, and plastics
- Building materials
Agricultural Chemicals
- Methyl bromide fumigant (phased out due to ozone depletion)
- Herbicides and pesticides
Chemical Industry
- Organic synthesis
- Dyes and pharmaceuticals
- Brominated compounds
Other Uses
- Water treatment
- Photography (silver bromide, historical)
- Drilling fluids (clear brines)
- Medical imaging agents
Biological Role
Bromine was recently discovered to be essential for humans—required for basement membrane assembly.
In the Human Body
- About 260 mg in adult body
- Found mainly in thyroid gland and blood
- Essential for collagen IV network formation
- Required for tissue development
Dietary Sources
Grains, nuts, fish, and seaweed contain bromine.
Safety and Hazards
Toxicity
Elemental bromine is highly toxic and corrosive. It causes severe burns to skin and respiratory tract. The vapor is dangerous even in low concentrations.
Handling Precautions
- Highly corrosive—causes severe burns
- Toxic vapors—requires excellent ventilation
- Wear appropriate PPE (gloves, respirator, goggles)
- Store in glass or Teflon containers
- Immediately dangerous to life at 3 ppm
Environmental Impact
Brominated compounds can persist in the environment. Some brominated flame retardants are bioaccumulative. Methyl bromide depletes the ozone layer.
Interesting Facts
- Bromine is the only nonmetallic element that is liquid at room temperature
- Its vapor is so dense that it can be "poured" from one container to another
- Ancient Tyrian purple dye (from sea snails) contains bromine
- Bromine was recently (2014) established as an essential element for humans
- The Dead Sea has such high bromine content that it was once called "Lake Asphaltites"