Barium (Ba) – element 56
Barium is a chemical element with the symbol Ba and atomic number 56. It is a alkaline earth metal in group 2 (alkaline earth metals), period 6 of the periodic table (s-block), and is a solid at room temperature.
Barium (Ba) has atomic number 56, atomic mass 137.33 u and electron configuration [Xe] 6s2.
Barium facts
| Symbol | Ba |
|---|---|
| Atomic number | 56 |
| Atomic mass | 137.33 u (g/mol) |
| Category | alkaline earth metal |
| Group | group 2 (alkaline earth metals) |
| Period | 6 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 |
| Noble-gas notation | [Xe] 6s2 |
| Electrons per shell | 2, 8, 18, 18, 8, 2 |
| Valence electrons | 2 |
Bohr model and shells
Barium has 56 electrons in 6 shells: 2, 8, 18, 18, 8, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 1000 K (726.9 °C) |
|---|---|
| Boiling point | 2118 K (1844.8 °C) |
| Density | 3.51 g/cm³ |
| Electronegativity (Pauling) | 0.89 |
| Electron affinity | 13.954 kJ/mol |
| Ionization energies | 502.9, 965.2, 3600 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 28.07 J/(mol·K) |
| Discovered by | Carl Wilhelm Scheele |
Use the atomic mass in the molar mass calculator for any formula containing Ba.
Position in the periodic table
Tap any element to open its page.
Frequently asked questions
What is the atomic mass of barium?
The atomic mass of barium is 137.33 u, so one mole of barium atoms weighs 137.33 g.
What is the electron configuration of barium?
Barium has 56 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s², or [Xe] 6s² in noble-gas notation. Electrons per shell: 2, 8, 18, 18, 8, 2.
How many valence electrons does barium have?
Barium has 2 valence electrons (group 2).
Is barium a metal?
Yes. Barium is a alkaline earth metal.
Where is barium on the periodic table?
Barium is in group 2 (alkaline earth metals), period 6, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.