Periodic Table
4
Be
9.0122
Beryllium
Alkaline EarthAnomalous Group 2 metal; covalent, amphoteric oxide; diagonal with Al.
Electronic Configuration
1s² 2s²or1s² 2s²
Electron shells
2e⁻n=1
2e⁻n=2
Properties
Atomic number
4
Atomic mass
9.0122 u
Category
Alkaline Earth
Block / Group / Period
s · 2 · 2
Valence electrons
2
Oxidation states
+2
Electronegativity
1.57
Atomic radius
112 pm
Ionization energy
899 kJ/mol
Electron affinity
-48 kJ/mol
Melting point
1560 K / 1287 °C
Boiling point
2742 K / 2469 °C
Density
1.85 g/cm³
State at 25 °C
solid
JEE / NEET notes
- Diagonal relationship with Al.
- Forms covalent compounds (BeCl₂ is polymeric/covalent, electron deficient).
- Amphoteric oxide BeO; does not impart flame colour.
- Does not react with water even on heating.
Exceptions
- • Anomalous Group 2 element — covalent character, max covalency 4.
Ores & extraction
Ores: Beryl (Be₃Al₂Si₆O₁₈)
Uses
X-ray windows · Aerospace alloys · Nuclear reactors
Important compounds
BeCl₂BeOBeF₂
Personal Notes
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