Chemical element · Atomic number 35
Bromine
Bromine in the periodic table: atomic number 35, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Halogen
liquid
79.90 u
Documented element sampleAbout two grams of bromine at 99.8 percent purity, sealed in a borosilicate ampoule and cast in an acrylic cube.
Image credit: Alchemist-hp ( pse-mendelejew.de )
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Bromine in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 7 electrons
- Electron configuration
- [Ar]4s2 3d10 4p5
- Electrons per shell
- 2 · 8 · 18 · 7
- Group
- 17
- Period
- 4
- Block
- P
- Element category
- Halogen
Physical and chemical properties
- Atomic mass
- 79.90 u
- Standard state
- liquid
- Density
- 3.11 g/cm³
- Melting point
- 265.95 K
- Boiling point
- 331.95 K
- Electronegativity
- 2.96 (Pauling)
- First ionisation energy
- 11.814 eV
- Oxidation states
- +5, +1, -1
- Discovery
- 1826
Safety and periodic classification
Safety
Safe handling cannot be inferred from Bromine's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Bromine is in period 4, group 17 and the P block. Its direct neighbours by atomic number are Selenium and Krypton. The recorded Pauling electronegativity is 2.96. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Bromine sits among the 118 elements
The table compares the reported values for Bromine with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Bromine | Position in the data set |
|---|---|---|
| Melting point | 265.95 K | Rank 91 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 331.95 K | Rank 82 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 3.11 g/cm³ | Rank 69 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 2.96 | Rank 6 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 11.814 eV | Rank 11 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Bromine in the periodic table
- Place in the table
- Group 17, period 4, P block. Classified as halogen, liquid at standard conditions.
- Direct neighbours
- Atomic number 35. Preceded by Selenium, followed by Krypton.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Fluorine, Chlorine, Iodine, Astatine, Tennessine.
- Discovery
- Recorded in the snapshot as: 1826. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- +5, +1, -1. They follow from the electron configuration [Ar]4s2 3d10 4p5 and indicate which compounds to expect.
Go from looking up chemistry to remembering it.
Turn your notes into source-backed study cards and review them at the right time.
Starter stays free · no payment details