Bromine (Br)
Halogen · p-block · period 4 · group 17
Dense, dark red-brown liquid that gives off choking orange vapour.
Bromine (symbol Br) is chemical element number 35, a halogen in group 17, period 4 of the periodic table. Its standard atomic weight is 79.904 and its electron configuration is [Ar] 3d10 4s2 4p5. At room temperature it is a liquid. One of only two elements that are liquid at room temperature (with mercury).
Properties
| Atomic number | 35 |
|---|---|
| Atomic mass | 79.904 |
| Category | Halogen |
| Block | p-block |
| Group · Period | 17 · 4 |
| Electron configuration | [Ar] 3d10 4s2 4p5 |
| Electrons per shell | 2, 8, 18, 7 |
| State at 25 °C | liquid |
| Melting point | 265.8 K |
| Boiling point | 332 K |
| Density | 3.1028 g/cm³ |
| Electronegativity (Pauling) | 2.96 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1826 · Antoine Jérôme Balard |
Key facts about Bromine
- One of only two elements that are liquid at room temperature (with mercury).
- Its name is Greek for 'stench'.
- Extracted from seawater and salt-lake brines.
- Bromine compounds were widely used as flame retardants in electronics and furniture.
What Bromine is used for
Flame retardants, water treatment, agricultural fumigants, photographic film, drilling fluids.
Where it sits in the periodic table
Bromine is in group 17, period 4, of the p-block. Its electron configuration [Ar] 3d10 4s2 4p5 means its outermost shell holds 7 electrons, which is what places it here and explains much of its chemistry. See Bromine on the interactive table →
Bromine — frequently asked questions
What is Bromine used for?
Flame retardants, water treatment, agricultural fumigants, photographic film, drilling fluids.
Is Bromine radioactive?
No. Bromine has at least one stable isotope and is not radioactive.
What is the electron configuration of Bromine?
Bromine has the electron configuration [Ar] 3d10 4s2 4p5, which is 2, 8, 18, 7 electrons per shell.
What group and period is Bromine in?
Bromine is in group 17, period 4, in the p-block. Its outer shell holds 7 electrons.
Who discovered Bromine?
Bromine was discovered in 1826 by Antoine Jérôme Balard.