Ba
Barium
Element 56 · Alkaline earth metal
Barium (Ba)
Barium is a soft, silvery alkaline earth metal. Its insoluble sulfate lets doctors see the digestive tract on X-rays.
- Alkaline earth metal
- Period 6
- Group 2
- s-block
- solid at room temperature
Key properties
- Atomic mass
- 137.33
- u
- Electron configuration
- [Xe] 6s2
- Melting point
- 726.9 °C
- 1,000 K
- Boiling point
- 1,896.9 °C
- 2,170 K
- Density
- 3.62 g/cm³
- Electronegativity
- 0.89
- Pauling
- Atomic radius
- 268 pm
- van der Waals
- 1st ionisation energy
- 5.212 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about barium
- 01
Scheele recognised barium oxide in 1772; Humphry Davy isolated the metal in 1808.
- 02
Barium salts colour fireworks green.
- 03
Soluble barium compounds are poisonous, but barium sulfate passes through the body harmlessly.
Applications
What is barium used for?
- X-ray contrast (barium meal)
- Oil drilling mud
- Green fireworks
- Glass and ceramics
History
Discovery & name origin
Discovered by
Year
Where
Sweden
Name origin
Greek barys, “heavy”, for the density of its minerals.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 56
- Atomic mass
- 137.33 u
- Group
- 2
- Period
- 6
- Block
- s-block
- Electron configuration
- [Xe] 6s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
- Electrons per shell
- 2, 8, 18, 18, 8, 2
- Electronegativity (Pauling)
- 0.89
- Electron affinity
- —
- Atomic radius (van der Waals)
- 268 pm
- Stable isotopes
- 6
Oxidation states
Highlighted: common oxidation states (+2).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st502.9
- 2nd965.2
- 3rd3,600
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,000 K · 726.9 °C · 1,340.3 °F
- Boiling point
- 2,170 K · 1,896.9 °C · 3,446.3 °F
- Density
- 3.62 g/cm³
- Molar heat capacity
- 28.07 J/(mol·K)
- Appearance
- —
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Barium questions
What is Ba on the periodic table?
Ba is the symbol for barium, element 56 on the periodic table. It sits in group 2, period 6, in the alkaline earth metal category, and has an atomic mass of 137.33.
What is the atomic number of barium?
Barium has atomic number 56, so every barium atom has 56 protons in its nucleus. Its symbol is Ba and its atomic mass is 137.33.
Who discovered barium?
Barium was discovered by Carl Wilhelm Scheele in 1772 (Sweden). The name comes from Greek barys, “heavy”, for the density of its minerals.
What is barium used for?
Barium is used for: X-ray contrast (barium meal); oil drilling mud; green fireworks; glass and ceramics.
Is barium a metal?
Yes. Barium is a alkaline earth metal, one of the metallic elements.
What is the electron configuration of barium?
The electron configuration of barium is [Xe] 6s2. Its 56 electrons are arranged in shells as 2, 8, 18, 18, 8, 2.