3579.904BrBromine
Bromine (Br) — element 35halogen · group 17, period 4
Bromine is a chemical element with the symbol Br and atomic number 35. It is a halogen in group 17, period 4 of the periodic table (the p-block), with a standard atomic mass of 79.904 u. At room temperature (25 °C) bromine is a liquid.
💡 Known for: One of only two elements that are liquid at room temperature; used in flame retardants.
# Bromine properties
| Symbol | Br |
|---|---|
| Atomic number | 35 |
| Atomic mass | 79.904 u |
| Category | halogen |
| Group | 17 |
| Period | 4 |
| Block | p-block |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p⁵ |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵ |
| Electrons per shell | 2, 8, 18, 7 |
| Protons / electrons | 35 / 35 |
| State at 25 °C | liquid |
| Melting point | 265.8 K (-7.3 °C, 18.8 °F) |
| Boiling point | 332 K (58.9 °C, 137.9 °F) |
| Density | 3.122 g/cm³ |
| Electronegativity (Pauling) | 2.96 |
| First ionization energy | 11.814 eV |
| Atomic radius | 94 pm |
| Discovered | 1826 |
# Electron configuration of bromine
The electron configuration of bromine is [Ar] 3d¹⁰ 4s² 4p⁵, written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵. Its 35 electrons fill 4 shells as 2, 8, 18, 7, so the outermost shell holds 7 electrons. As a group 17 element, bromine has 7 valence electrons.
# Related elements
SeSeleniumprevious elementKrKryptonnext elementFFluorinegroup 17ClChlorinegroup 17IIodinegroup 17AtAstatinegroup 17TsTennessinegroup 17
# Bromine FAQ
What is the atomic number of bromine?
The atomic number of bromine is 35: every bromine atom has 35 protons in its nucleus. Its symbol is Br.
What is the atomic mass of bromine?
The standard atomic mass of bromine is 79.904 u.
What is the electron configuration of bromine?
Bromine's electron configuration is [Ar] 3d¹⁰ 4s² 4p⁵ (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵), with 2, 8, 18, 7 electrons per shell.
Is bromine a metal?
No. Bromine is a halogen, a nonmetal.
What is the melting point of bromine?
Bromine melts at 265.8 K (-7.3 °C, 18.8 °F) and boils at 332 K (58.9 °C, 137.9 °F).
What is bromine used for / known for?
One of only two elements that are liquid at room temperature; used in flame retardants.