Beryllium vs Boron

Side-by-side comparison of Beryllium (Be, element 4) and Boron (B, element 5) by atomic structure and physical properties.

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PropertyBe Beryllium B Boron
Atomic number45
SymbolBeB
NameBerylliumBoron
Categoryalkaline-earth-metalmetalloid
Standard Atomic Weight9.012183 u10.8135 u
Period22
Group213
Blocksp
Phase at STPSolidSolid
Electron configuration[He]2s2[He]2s22p1
Oxidation states[0, 1, 2][-5, -1, 0, 1, 2, 3]
Electronegativity (Pauling)1.572.04
Electron affinity-0.5 eV0.27972 eV
Density1850 kg/m³2370 kg/m³
Melting point1286.85 °C2074.85 °C
Boiling point2470.85 °C3999.85 °C
Discovery year17971808

Key Differences

PropertyBe BerylliumB Boron
Standard Atomic Weight9.012183 u ↓ lower10.8135 u ↑ higher
Density1850 kg/m³ ↓ lower2370 kg/m³ ↑ higher
Melting point1286.85 °C ↓ lower2074.85 °C ↑ higher
Boiling point2470.85 °C ↓ lower3999.85 °C ↑ higher
Electronegativity (Pauling)1.57 ↓ lower2.04 ↑ higher
Electron affinity-0.5 eV ↓ lower0.27972 eV ↑ higher
Group2 13
Blocks p
Categoryalkaline-earth-metal metalloid
Electron configuration[He]2s2 [He]2s22p1
Discovery year1797 1808