Bromine (Br)

Reddish-brown liquid

Bromine is one of only two elements liquid at room temperature, with a pungent, suffocating vapor, and as the only non-metallic element that is liquid at standard conditions (266 K melting point), bromine has a high electron affinity (3.36 eV). It is used in flame retardants, water treatment, and photographic film.

Key metrics

Density3.12g/cm³

Melting point266K

Boiling point332K

Electronegativity2.96Pauling

Discovery

1826discovered

Discovered by: Antoine Jérôme Balard
Reactivity profile: Highly reactive halogen
Reactivity: High
Bonding: Covalent

Electron configuration

\textcolor{#6b7280}{[Ar]}\; \textcolor{#22c55e}{3_{d}^{10}}\; \textcolor{#ef4444}{4_{s}^{2}}\; \textcolor{#3b82f6}{4_{p}^{5}}

[Ar] 3d10 4s2 4p5

Wave function

\Psi_{\text{Br}} \approx \frac{1}{\sqrt{35!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{35}(\mathbf{r}_{35}) \right|

Probability density $|\Psi|^2$ across the Br valence shell.

Crystal structure

Orthorhombic

Lattice constantsa 1.00 · b 1.30 · c 0.90

Cell anglesα = β = γ = 90°

Coordination number—

Atoms per cell—

Atomic packing factor0.60

Physical properties

Atomic radius: 94 pm
Ionization energy: 1140 kJ/mol
Electron affinity: 324 kJ/mol
Crystal structure: Orthorhombic

Oxidation states

-1+1+5

Acid/base

Acidic

Strongly acidicStrongly basic

State at 25 °CLiquid

266 K332 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

478.6nmBr I (blue)Blue100%

518.4nmBr I (green)Green60%

635.1nmBr I (red)Red40%

Dominant line 478.6 nmRange 479–635 nmTransitions 3