Beryllium (Be)

Beryllium properties

Atomic number

4

Atomic mass

9.0122 u

Category

Alkaline earth metal

Group

2

Period

2

Block

s-block

State at room temp.

Solid

Electronegativity

1.57

Melting point

1,560 K (1,286.8 °C)

Boiling point

2,742 K (2,468.8 °C)

Density

1.85 g/cm³

Valence electrons

2

Common charges

+2

Oxidation states

+2

Atomic radius

153 pm

Ionization energy

9.323 eV

Electron affinity

—

Radioactive

No, has stable isotopes

Discovered

1798

Beryllium electron configuration

The electron configuration of Beryllium (Be) is [He] 2s2. Its 4 electrons are arranged in shells as 2, 2.

Protons, neutrons and electrons in Beryllium

A neutral Beryllium atom has 4 protons and 4 electrons. Most Beryllium atoms have about 5 neutrons: the atomic mass rounded to 9, minus the atomic number 4.

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

How many valence electrons does Beryllium have?

2

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

See every element: Periodic table with valence electrons

Beryllium 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 Beryllium

9.0122 g/mol

One mole of Beryllium atoms (6.022 × 10²³ atoms) has a mass of 9.0122 grams. Use this value to convert between grams and moles.

Beryllium facts

• Emerald and aquamarine are both gem varieties of beryl, a mineral made of beryllium, aluminum, silicon and oxygen.
• Beryllium was once called glucinium because some of its compounds taste sweet, but beryllium compounds are highly toxic and should never be tasted.
• Beryllium (Be) has atomic number 4 and is a solid at room temperature. It was discovered in 1798.

Position in the periodic table

Beryllium is element 4, in period 2 and group 2 of the periodic table, in the s-block.

All alkaline earth metals

Uses of Beryllium

Beryllium is added in small amounts to copper to make strong, springy alloys for electrical connectors and for non-sparking tools used around flammable gases. Because X-rays pass through it easily, thin beryllium sheets serve as windows in X-ray tubes and detectors. Its lightness and stiffness also suit aerospace parts, and the 18 mirror segments of the James Webb Space Telescope are made of gold-coated beryllium.

Who discovered Beryllium?

French chemist Louis-Nicolas Vauquelin discovered beryllium in 1798, as an oxide in the minerals beryl and emerald. The metal itself was first isolated in 1828, independently by Friedrich Wöhler and Antoine Bussy.

Where does the name come from?

Beryllium is named after beryl, the mineral in which it was discovered, from the Greek beryllos. It was long called glucinium, from the Greek glykys, 'sweet', because some of its compounds taste sweet.

Discovery timeline