Bromine

Bromine was first discovered in 1826 by the French chemist Antoine Jérôme Balard, who isolated it from the residue left after the evaporation of seawater. Balard was intrigued by the reddish-brown coloration of the substance and its pungent smell, which reminded him of chlorine and iodine. The name 'bromine' is derived from the Greek word 'bromos', meaning 'stench'. Although Balard was the first to successfully isolate bromine, the German chemist Gottlieb Kirchhoff independently discovered it around the same time using a different methodology. The industrial production of bromine began in the late 19th century, primarily from brine, which is saltwater containing significant amounts of bromine.

Bromine is relatively rare in the Earth's crust, occurring at an average concentration of about 0.0007% by weight. It is primarily found in the form of bromide ions (Br-) in seawater and mineral deposits, where it often exists in association with other salt minerals. The highest concentrations of bromine can be found in hypersaline lakes, such as the Dead Sea and the Great Salt Lake, where it can reach levels up to 0.01% by weight. Bromine is also produced commercially through the evaporation and crystallization of seawater and brine, where, alongside other salts, bromides are collected for various applications.

Bromine plays a minor but essential role in biological systems. Although it is not considered an essential element for human survival, it does have some biological significance. Brominated compounds occur naturally and exhibit anti-inflammatory, antimicrobial, and potential neuroprotective effects. Certain species of marine life and algae utilize bromine in their metabolic processes. Additionally, bromine and its compounds contribute to the formation of certain enzymes in microorganisms, indicating that it may have a broader ecological function in marine ecosystems.

Bromine is a dark reddish-brown liquid under standard conditions, with a melting point of -7.2 °C and boiling point of 58.8 °C. It has a high vapor pressure, which enables it to emit a vapor that is both toxic and irritating to the respiratory system. The density of bromine is approximately 3.12 g/cm³, making it the heaviest nonmetallic element. Chemically, bromine is highly reactive, particularly with alkali metals and alkaline earth metals, to form a variety of bromide salts. Bromine also readily undergoes addition reactions with alkenes and alkynes, forming organobromine compounds that are significant in organic chemistry.

Bromine has various industrial and commercial applications, particularly in the manufacture of flame retardants, which are crucial for enhancing the fire safety of materials in construction and textiles. Additionally, bromine compounds are utilized in the production of certain pesticides, pharmaceuticals, and disinfectants. In water treatment processes, bromine serves as a biocide to control bacteria and algae growth. Also noteworthy is its application in the synthesis of photographic chemicals, as well as its role in the production of certain types of dyes and agrochemicals, contributing to its significance in various sectors.

• Bromine is one of only two elements that are liquid at room temperature, the other being mercury.
• Bromine was originally discovered in the early 19th century, but its commercial production did not begin until the late 1800s.
• In its pure form, bromine is corrosive and can cause burns, and its vapors can irritate the skin and respiratory system.
• Bromine is used as a biocide in swimming pools and hot tubs, offering a more stable alternative to chlorine.