Bromine
Symbol: Br
Atomic Number: 35
Atomic Mass: 79.904 amu (atomic mass units)
Melting Point: minus 7.2°C (265.95 K, 19.04°F)
Boiling Point: 58.78°C (331.93 K, 137.804°F)
Number of Protons: 35
Number of Electrons: 35
Number of Neutrons: 45
Classification: Halogen
Crystal Structure: Orthorhombic
Density @ 293 K: 3.119 grams per cubic centimeter
Color: Red-brown with a metallic luster when solid
Bromine was first produced by a young student, Carl Lowig, the summer before he started his freshman year at Heidelberg University. He showed his professor, Leopold Gmelin, the red liquid he had produced and the professor realized that this was an unknown element. Unfortunately for Lowig, winter exams and the holidays delayed any further work. This allowed another chemist Antoine-Jerome Balard, to publish a paper in 1826 which described the new element. Therefore it was Balard who was credited with the discovery of the new element and he named it after the Greek word for stench, “bromos” as it is rather smelly.
Bromine is the only non-metallic element that is liquid at room temperature. There is only one other element that is liquid at room temperature and that is mercury. Bromine is a heavy, volatile and dangerous reddish-brown liquid. When it vaporizes the red vapor has a strong very unpleasant odor. This vapor will irritate the eyes, nose and throat. If spilled on bare skin it can produce painful sores. As it is a health hazard safety precautions should be taken when handling this element.
There are two stable isotopes of bromine. Bromine-79 is the most common at 50.69% the other being bromine-81 which accounts for the rest of the total abundance. There are thirty seven unstable isotopes currently recognized for this element. The half lives of the unstable isotopes range from less than 24 nanoseconds to 37.036 hours.
Despite its hazardous nature bromine has a number of uses.
* It used to be added to leaded petroleum in the form of 1,2-dibromoethane (ethylene di-bromide) to prevent damaging lead buildup in engines. With the increased usage of unleaded petroleum this use is now diminished
* Sliver bromide is used in photography.
* It is used as a fumigant.
* Bromine can be used as a flame-proofing agent.
* Some bromine compounds are used in water purification.
* The valuable ancient dye much valued by the Romans, Tyrian purple, is a natural bromine compound produced by the sea mussel Murex.
