Barium (Ba)

Barium properties

Atomic number

56

Atomic mass

137.33 u

Category

Alkaline earth metal

Group

2

Period

6

Block

s-block

State at room temp.

Solid

Electronegativity

0.89

Melting point

1,000 K (726.8 °C)

Boiling point

2,118 K (1,844.8 °C)

Density

3.51 g/cm³

Valence electrons

2

Common charges

+2

Oxidation states

+2

Atomic radius

268 pm

Ionization energy

5.212 eV

Electron affinity

—

Radioactive

No, has stable isotopes

Discovered

1808

Barium electron configuration

The electron configuration of Barium (Ba) is [Xe] 6s2. Its 56 electrons are arranged in shells as 2, 8, 18, 18, 8, 2.

Protons, neutrons and electrons in Barium

A neutral Barium atom has 56 protons and 56 electrons. Most Barium atoms have about 81 neutrons: the atomic mass rounded to 137, minus the atomic number 56.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Barium have?

2

Barium has 2 valence electrons in its outermost shell, shell 6. These are the electrons involved in chemical bonding.

See every element: Periodic table with valence electrons

Barium orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Barium

137.33 g/mol

One mole of Barium atoms (6.022 × 10²³ atoms) has a mass of 137.33 grams. Use this value to convert between grams and moles.

Compounds containing Barium

Barium facts

• Barium's name comes from the Greek barys, meaning 'heavy', after its dense mineral barite.
• Barium sulfate is safe to swallow because it does not dissolve, but soluble barium compounds such as barium chloride are poisonous.
• Barium (Ba) has atomic number 56 and is a solid at room temperature. It was discovered in 1808.

Position in the periodic table

Barium is element 56, in period 6 and group 2 of the periodic table, in the s-block.

All alkaline earth metals

Uses of Barium

Barium is mined mostly as the mineral barite (barium sulfate), which is ground up and added to drilling fluids to make them heavy enough to control pressure in oil and gas wells. Doctors use a barium sulfate 'barium meal' to make the digestive tract show up on X-rays. Barium compounds also give fireworks a green color and are used in glass, ceramics, and capacitors.

Who discovered Barium?

English chemist Humphry Davy first isolated barium metal in 1808 in London by electrolysis of barium compounds. Carl Wilhelm Scheele had already recognized its oxide, baryta, as a new substance in 1774.

Where does the name come from?

Barium comes from baryta, an old name for barium oxide, from the Greek barys, meaning 'heavy'. Its common mineral, baryte (barite), is unusually dense, and Humphry Davy named the metal in 1808 after isolating it.

Discovery timeline