Bromine
Pronunciation | /ˈ b r oʊ m iː n, -m ɪ n, -m aɪ n/ ​(BROH-meen, -⁠min, -⁠myn)
Appearance | reddish-brown
Standard atomic weight Ar, std(Br) | [79.901, 79.907] conventional: 79.904
Atomic number (Z) | 35
Group | group 17 (halogens)
Period | period 4
Block | p-block
Element category | Reactive nonmetal
Electron configuration | [Ar] 3d10 4s2 4p5
Electrons per shell | 2, 8, 18, 7
Phase at STP | liquid
Melting point | (Br2) 265.8 K ​(−7.2 °C, ​19 °F)
Boiling point | (Br2) 332.0 K ​(58.8 °C, ​137.8 °F)
Density (near r.t.) | Br2, liquid: 3.1028 g/cm3
Triple point | 265.90 K, ​5.8 kPa
Critical point | 588 K, 10.34 MPa
Heat of fusion | (Br2) 10.571 kJ/mol
Heat of vaporisation | (Br2) 29.96 kJ/mol
Molar heat capacity | (Br2) 75.69 J/(mol·K)
Oxidation states | −1, +1, +3, +4, +5, +7 (a strongly acidic oxide)
Electronegativity | Pauling scale: 2.96
Ionisation energies | 1st: 1139.9 kJ/mol 2nd: 2103 kJ/mol 3rd: 3470 kJ/mol
Atomic radius | empirical: 120 pm
Covalent radius | 120±3 pm
Van der Waals radius | 185 pm
Natural occurrence | primordial
Speed of sound | 206 m/s (at 20 °C)
Thermal conductivity | 0.122 W/(m·K)
Electrical resistivity | 7.8×1010 Ω·m (at 20 °C)
Magnetic ordering | diamagnetic
Magnetic susceptibility | −56.4·10−6 cm3/mol
CAS Number | 7726-95-6
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Discovery and first isolation | Antoine Jérôme Balard and Carl Jacob Löwig (1825)