Element: Bromine
General data
| Element name | Bromine |
|---|---|
| Chemical symbol | Br |
| Atomic number Z | 35 |
| Year discovered | 1826 |
| Standard state (25°C) | Liquid |
| Category | Halogen |
| Block | p |
| Atomic mass | 79.904 |
| CPK color | #A62929 |
Physical properties
| Melting point | 265.95 K (-7.20 °C) |
|---|---|
| Boiling point | 331.95 K (58.80 °C) |
| Density | 3.11 g/cm³ |
Energy properties
| First ionization energy | 11.814 eV |
|---|---|
| Electron affinity | 3.365 eV |
Atomic structure
| Protons | 35 (Atomic number) |
|---|---|
| Neutrons (Br-79, most abundant isotope) | 44 |
| Electrons | 35 |
| Electron configuration | [Ar] 4s² 3d¹⁰ 4p⁵ |
| Oxidation states | +5, +1, -1 |
| Electronegativity (Pauling) | 2.96 |
| Atomic radius (van der Waals) | 183 pm |
Ionization energies - NIST ASD (35 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Br I | 0+ | 11.81381 ± 0.00006 | measured |
| Br II | 1+ | 21.591 | measured |
| Br III | 2+ | 34.871 ± 0.019 | measured |
| Br IV | 3+ | 47.782 ± 0.012 | measured |
| Br V | 4+ | 59.595 ± 0.025 | measured |
| Br VI | 5+ | 87.39 ± 0.025 | measured |
| Br VII | 6+ | 103.03 ± 0.19 | semi-empirical |
| Br VIII | 7+ | 192.61 ± 0.06 | measured |
| Br IX | 8+ | 224 ± 2.2 | calculated |
| Br X | 9+ | 261 ± 2.2 | calculated |
| Br XI | 10+ | 301 ± 2.4 | calculated |
| Br XII | 11+ | 338 ± 2.5 | calculated |
| Br XIII | 12+ | 393 ± 3 | calculated |
| Br XIV | 13+ | 436 ± 3 | calculated |
| Br XV | 14+ | 481 ± 3 | calculated |
| Br XVI | 15+ | 530 ± 3 | calculated |
| Br XVII | 16+ | 577 ± 3 | calculated |
| Br XVIII | 17+ | 716.3 ± 2.3 | semi-empirical |
| Br XIX | 18+ | 761 ± 0.8 | semi-empirical |
| Br XX | 19+ | 809.8 ± 1.2 | semi-empirical |
| Br XXI | 20+ | 870 ± 3 | semi-empirical |
| Br XXII | 21+ | 920.8 ± 2.2 | semi-empirical |
| Br XXIII | 22+ | 963 ± 5 | semi-empirical |
| Br XXIV | 23+ | 1070.6 ± 1.4 | semi-empirical |
| Br XXV | 24+ | 1119.17 ± 0.04 | semi-empirical |
| Br XXVI | 25+ | 2731.4 ± 1.5 | semi-empirical |
| Br XXVII | 26+ | 2869 ± 5 | semi-empirical |
| Br XXVIII | 27+ | 3021 ± 7 | semi-empirical |
| Br XXIX | 28+ | 3169 ± 24 | semi-empirical |
| Br XXX | 29+ | 3361 ± 3 | semi-empirical |
| Br XXXI | 30+ | 3523.1 ± 2.2 | semi-empirical |
| Br XXXII | 31+ | 3735 ± 4 | semi-empirical |
| Br XXXIII | 32+ | 3868.986 ± 0.007 | calculated |
| Br XXXIV | 33+ | 16317.014 ± 0.004 | calculated |
| Br XXXV | 34+ | 16937.1497 ± 0.0015 | calculated |
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
Photos
Isotopes (32)
| A | N | Half-life | Decay |
|---|---|---|---|
| Br-68 | 33 | 35 ns | p |
| Br-69 | 34 | < 24 ns | p |
| Br-70 | 35 | 78.9 ms | EC/β⁺ |
| Br-71 | 36 | 21.4 s | EC/β⁺ |
| Br-72 | 37 | 78.6 s | EC/β⁺ |
| Br-73 | 38 | 3.4 min | EC/β⁺ |
| Br-74 | 39 | 25.4 min | EC/β⁺ |
| Br-75 | 40 | 96.7 min | EC/β⁺ |
| Br-76 | 41 | 16.16 h | EC/β⁺ |
| Br-77 | 42 | 57.04 h | EC/β⁺ |
| Br-78 | 43 | 6.45 min | EC/β⁺ |
| Br-79 | 44 | stable | - |
| Br-80 | 45 | 17.68 min | β⁻ |
| Br-81 | 46 | stable | - |
| Br-82 | 47 | 35.284 h | β⁻ |
| Br-83 | 48 | 2.374 h | β⁻ |
| Br-84 | 49 | 31.76 min | β⁻ |
| Br-85 | 50 | 2.94 min | β⁻ |
| Br-86 | 51 | 55.1 s | β⁻ |
| Br-87 | 52 | 55.68 s | β⁻ |
| Br-88 | 53 | 16.34 s | β⁻ |
| Br-89 | 54 | 4.348 s | β⁻ |
| Br-90 | 55 | 1.91 s | β⁻ |
| Br-91 | 56 | 544 ms | β⁻ |
| Br-92 | 57 | 344 ms | β⁻ |
| Br-93 | 58 | 152 ms | β⁻ |
| Br-94 | 59 | 70 ms | β⁻ |
| Br-95 | 60 | unknown | β⁻ |
| Br-96 | 61 | unknown | β⁻ |
| Br-97 | 62 | unknown | β⁻ |
| Br-98 | 63 | unknown | β⁻ |
| Br-101 | 66 | unknown | β⁻ |
Data sources
- PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
- IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
- NIST Atomic Spectra Database (ASD) - Retrieved on 29 June 2026 - licence: © U.S. Secretary of Commerce
- Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0