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4Be9.0122
Alkaline Earth Metalssolid at STPS-block

Beryllium

Group: 2Period: 2Standard Atomic Weight: 9.0122 u

Why is Beryllium in this position?

Understanding the scientific rationale behind Beryllium's position in the periodic table:

Group Assignment
Group 2

Placed in Group 2 because its neutral atom has 2 valence electrons in the s-orbital (2s²).

Period Assignment
Period 2

Placed in Period 2 because its outermost occupied shell is n=2.

Orbital Block
S-block

Belongs to the s-block because its valence subshell is an s-orbital.

Chemical Category
Alkaline Earth Metals

Classified as an alkaline earth metal, though its small ionic radius causes anomalous covalent character and amphoteric oxide behavior.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 2]

Bohr Atomic Shell Model(2, 2)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

4 Protons (p⁺)5 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 2Shell L: Electron 2 of 2BeZ = 4

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):2 / 8 electrons (25%)
Aufbau Electron Configuration
1s² 2s²

Neutral ground state configuration. Valence electrons: 2.

Atomic & Quantum Properties

Electronegativity (Pauling)1.57 Pauling
1st Ionization Energy899.5 kJ/mol
Electron Affinity0 kJ/mol
Atomic Radius (empirical)112 pm
Common Oxidation States+2
Crystal StructureHCP

Physical & Thermal Properties

Density at STP1.85 g/cm³
Melting Point1287 °C (1560 K)
Boiling Point2469 °C (2742 K)
Magnetic OrderingDiamagnetic
Discovery Year1798
Discovered ByLouis-Nicolas Vauquelin

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • X-ray tube transmission output windows
  • James Webb Space Telescope primary beryllium-gold mirror segments
  • Non-sparking beryllium-copper safety tools for oil rigs and explosive environments
  • Neutron reflectors and moderators in nuclear reactors
Occurrence in Nature

Concentrated naturally in beryl (Be₃Al₂Si₆O₁₈) minerals including emeralds and aquamarines, and bertrandite ore.

Etymology & Name Origin

From Greek 'beryllos', referring to the gemstone mineral beryl

Important Chemical Compounds
BeO (Beryllium oxide)
BeCl₂ (Beryllium chloride)
BeSO₄ (Beryllium sulfate)
Interesting Chemical Facts
  • Beryllium compounds taste sugary-sweet, which originally earned the element the name 'Glucinium'.
  • It has one of the highest sound-transmission velocities of any metal (over 12,890 m/s).
  • Unlike other alkaline earth metals, beryllium forms predominantly covalent rather than ionic bonds due to high charge density.
Safety & Handling Note

Chronic inhalation of beryllium dust causes Berylliosis, an incurable and potentially fatal inflammatory lung condition.