Bromine (Br) – element 35
Bromine is a chemical element with the symbol Br and atomic number 35. It is a reactive nonmetal in group 17 (halogens), period 4 of the periodic table (p-block), and is a liquid at room temperature.
Bromine (Br) has atomic number 35, atomic mass 79.904 u and electron configuration [Ar] 3d10 4s2 4p5.
Bromine facts
| Symbol | Br |
|---|---|
| Atomic number | 35 |
| Atomic mass | 79.904 u (g/mol) |
| Category | reactive nonmetal |
| Group | group 17 (halogens) |
| Period | 4 |
| Block | p-block |
| Phase at 20 °C | Liquid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 |
| Noble-gas notation | [Ar] 3d10 4s2 4p5 |
| Electrons per shell | 2, 8, 18, 7 |
| Valence electrons | 7 |
Bohr model and shells
Bromine has 35 electrons in 4 shells: 2, 8, 18, 7. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 265.8 K (-7.3 °C) |
|---|---|
| Boiling point | 332 K (58.9 °C) |
| Density | 3.1028 g/cm³ |
| Electronegativity (Pauling) | 2.96 |
| Electron affinity | 324.537 kJ/mol |
| Ionization energies | 1139.9, 2103, 3470 kJ/mol (1st, 2nd, 3rd) |
| Discovered by | Antoine Jérôme Balard |
Use the atomic mass in the molar mass calculator for any formula containing Br.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of bromine?
The atomic mass of bromine is 79.904 u, so one mole of bromine atoms weighs 79.904 g.
What is the electron configuration of bromine?
Bromine has 35 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵, or [Ar] 3d¹⁰ 4s² 4p⁵ in noble-gas notation. Electrons per shell: 2, 8, 18, 7.
How many valence electrons does bromine have?
Bromine has 7 valence electrons (group 17).
Is bromine a metal?
No. Bromine is a nonmetal (reactive nonmetal).
Where is bromine on the periodic table?
Bromine is in group 17 (halogens), period 4, in the p-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.