Periodic Table


Atomic number: 35
Atomic weight: 79.904
Symbol: Br
Group number: 17
Electronic configuration: [Ar].3d10.4s2.4p5


Bromine is the only liquid nonmetallic element. It is a member of the halogen group. It is a heavy, volatile, mobile, dangerous reddish-brown liquid. The red vapour has a strong disagreeable odour, resembling chlorine, and is irritating effect to the eyes and throat. It has a bleaching action. When spilled on the skin it produces painful sores. It is a serious health hazard, and maximum safety precautions should be taken when handling it.

General information

Discoveror: Antoine-J. Balard
Date discovered: 1826
Discovered at: France
Meaning of name: From the Greek word "bromos" meaning "stench"

Physical data

Standard state: liquid at 298 K
Colour: red-brown, metallic lustre when solid
Density of solid at ambient temperature/kg m-3: no data
Molar volume/cm3: 19.78

Radii /pm

Atomic: 94
Covalent (single bond):
Pauling radius for the ion [Br]-: 195

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius77.389.222.9no data


Both values are quoted on the Pauling scale.

Pauling: 2.96
Allred Rochow: 2.74

Crystal Structure

structure: orthorhombic

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 265.8
boiling point: 332

Enthalpies /kJ mol-1

fusion: 10.57
vaporization: 29.7

single bond enthalpies:
Br-F Br-Cl Br-Br Br-I Br-Br
187 216 190 175 192.807

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
79Br78.9183361 (26)50.69 (7)
81Br80.916289 (6)49.31 (7)

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Br.html