Bromine (Br)
Reactive nonmetal
Bromine is one of only two elements liquid at room temperature — a deep red-brown, heavy, fuming liquid with a harsh smell. Its compounds serve in flame retardants, photography and water treatment.
Position on the periodic table
Atomic properties
| Atomic number | 35 |
|---|---|
| Atomic mass | 79.904 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 |
| Noble gas shorthand | [Ar] 3d10 4s2 4p5 |
| Electrons per shell | 2, 8, 18, 7 |
| Valence electrons (outer shell) | 7 |
| Common oxidation states | -1, +1, +5 |
| Electronegativity (Pauling) | 2.96 |
| Covalent radius (approx.) | 120 pm |
| First ionization energy | 1140 kJ/mol |
| Electron affinity | 324.5 kJ/mol |
Physical properties
| State at 25 °C | Liquid |
|---|---|
| Density | 3.103 g/cm³ |
| Melting point | -7.35 °C (265.8 K) |
| Boiling point | 58.85 °C (332 K) |
| Appearance | Not available |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of bromine
Bromine's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5, usually shortened to [Ar] 3d10 4s2 4p5. Its electrons occupy 4 shells (2, 8, 18, 7), placing it in period 4 of the p-block. The 7 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of bromine
- Flame retardants in electronics and furniture
- Water and spa disinfection
- Photographic film (silver bromide)
- Drilling fluids and some medicines
Biological role: Recent research suggests trace bromide may help build tissue scaffolds; not classically essential.
Occurrence: Extracted from bromide-rich brines, notably the Dead Sea.
Common compounds of bromine
History and discovery
Discovered: 1826 — Antoine Jérôme Balard. Name origin: From Greek bromos, meaning stench.
Antoine-Jérôme Balard identified bromine in 1826 from salt-marsh brines at Montpellier, France.
Safety notes
Liquid bromine burns skin severely and its vapour is toxic — it is strictly a fume-hood chemical.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Bromine
1. What is the chemical symbol of Bromine?
2. What is the atomic number of Bromine?
3. Which category does Bromine belong to?
4. What is the state of Bromine at room temperature?
5. Which period of the periodic table is Bromine in?
Bromine FAQs
What is the atomic number of bromine?
Bromine's atomic number is 35 — every bromine atom has 35 protons in its nucleus.
What is the symbol for bromine?
Br. From Greek bromos, meaning stench.
Is bromine a metal, nonmetal, or metalloid?
Bromine is classified as a reactive nonmetal.
What state is bromine at room temperature?
At about 25 °C, bromine is a liquid. It melts at -7.35 °C.
How many valence electrons does bromine have?
Bromine has 7 electrons in its outer shell (shell pattern: 2, 8, 18, 7).
What is bromine used for?
Key uses include: flame retardants in electronics and furniture; water and spa disinfection; photographic film (silver bromide).
Related elements
Keep working with this element
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