Element 4
Beryllium (Be)
Beryllium (Be) is element 4 of the periodic table, an alkaline earth metal in period 2, group 2 (s-block) with an atomic mass of 9.0122 and is a solid at standard conditions.
At a glance
- Atomic number
- 4
- Symbol
- Be
- Atomic mass
- 9.0122 u
- Category
- Alkaline earth metals
- Period
- 2
- Group
- 2
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2
- Shorthand configuration
- [He] 2s2
- Electrons per shell
- 2, 2
- Oxidation states
- +2
Physical properties
- Melting point
- 1,560 K (1,286.85 °C)
- Boiling point
- 2,742 K (2,468.85 °C)
- Density
- 1.85 g/cm³
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.57
- Atomic radius
- 112 pm
- Covalent radius
- 96 pm
- Van der Waals radius
- 153 pm
- First ionization energy
- 900 kJ/mol
- Electron affinity
- 0 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Be-9 | 9.01218 | 100% | Stable |
Common uses
- Aerospace alloys
- X-ray windows
- Nuclear reactors
- Gyroscopes
Discovery
- Year
- 1798
- Discovered by
- Louis Nicolas Vauquelin
- Country
- France
Frequently asked questions
- Is beryllium a metal?
- Yes. Beryllium is a metal, classified as an alkaline earth metal on the periodic table.
- How many protons does beryllium have?
- Beryllium has 4 protons. Its atomic number is 4, which is also the number of electrons in a neutral atom of beryllium.
- What group and period is beryllium in?
- Beryllium is in group 2 and period 2 of the periodic table, in the s-block.
- What is the atomic mass of beryllium?
- The atomic mass of beryllium is 9.0122 u (unified atomic mass units).
Keep exploring
Beryllium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.