Atomic Properties of Br
- Atomic Number of Br
- 35
- Atomic Mass of Br
- 79.9040 u
- Electron Configuration
- [Ar] 3d10 4s2 4p5
- Electronegativity
- 2.96
- Block
- p-block
- Group
- 17
- Period
- 4
Bromine (Br) is element 35 on the periodic table. Atomic mass of Br: 79.9040 u. Br is in period 4, group 17. Melting point of Br: 265.80 K.Density of Br: 3.10 g/cm³.
The only liquid nonmetal at room temperature—and it smells terrible
Possibly essential in trace amounts (recent research). Historically used as sedatives. Bromide ions accumulate and cause 'bromism.'
Discovered by Antoine J. Balard in France, 1826
Name origin: Greek: brômos (stench).
Halogen element. Red volatile liquid at room temperature. Its reactivity is somewhere between chlorine and iodine. Harmful to human tissue in a liquid state, the vapour irritates eyes and throat. Discovered in 1826 by Antoine Balard.
Bromine has 2 naturally occurring isotopes, plus 2 notable radioactive isotopes.
| Isotope | Atomic Mass (u) | Abundance | Half-Life | Decay Mode |
|---|---|---|---|---|
| 7535Br (Br-75)Bromine-75 isotope | 74.925776 | 0% | 96.7 minutes | β⁺, EC |
| 7735Br (Br-77)Bromine-77 isotope | 76.921379 | 0% | 57.04 hours | β⁺, EC |
| 7935Br (Br-79)Bromine-79 isotope | 78.9183376 | 50.69% | — | — |
| 8135Br (Br-81)Bromine-81 isotope | 80.9162897 | 49.31% | — | — |
Data source: NIH PubChem (aggregated from IUPAC, NIST)
Isotopes of Bromine have important real-world applications in science and industry.
77Br (with a half-life of 57 h) is used to label radiopharmaceuticals that bind to estrogen receptors for tumor imaging. 75Br (with a half-life of 97 min) is being used with positron emission tomography (PET) imaging [281].
It was once used in large quantities to make a compound that removed lead compound build up in engines burning leaded gasoline. Now it is primarily used in dyes, disinfectants, and photographic chemicals.
Occurs in compounds in sea water.
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