Quick Facts
| Property | Value |
|---|---|
| Symbol | Ge |
| Atomic Number | 32 |
| Atomic Mass | 72.63 u |
| Category | Metalloid |
| Period | 4 |
| Group | 14 |
| Block | p |
| Electron Configuration | [Ar] 3d¹⁰ 4s² 4p² |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 5.323 g/cm³ |
| Melting Point | 938.25°C (1211.40 K) |
| Boiling Point | 2833°C (3106 K) |
| Appearance | Grayish-white, lustrous, brittle metalloid |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Ar] 3d¹⁰ 4s² 4p² |
| Electronegativity | 2.01 (Pauling scale) |
| First Ionization Energy | 762.2 kJ/mol |
| Atomic Radius | 122 pm |
| Covalent Radius | 122 pm |
| Van der Waals Radius | 211 pm |
History and Discovery
Discovered by: Clemens Winkler Year of Discovery: 1886 Location: Freiberg, Germany
Etymology
Named after Germany ("Germania" in Latin), the homeland of its discoverer.
Discovery Story
Dmitri Mendeleev predicted "eka-silicon" in 1871 with remarkable accuracy. Clemens Winkler discovered germanium in 1886 in a new mineral called argyrodite. The properties matched Mendeleev's predictions almost exactly, further validating the periodic table's predictive power.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ⁷⁰Ge | 20.52% | Stable | - |
| ⁷²Ge | 27.45% | Stable | - |
| ⁷³Ge | 7.76% | Stable | - |
| ⁷⁴Ge | 36.52% | Stable | - |
| ⁷⁶Ge | 7.75% | 1.78 × 10²¹ years | β⁻β⁻ |
Occurrence
Natural Abundance
Germanium is relatively rare, comprising about 1.5 ppm of Earth's crust. It is dispersed in many minerals but concentrated in few. Found in sphalerite (zinc ore), coal, and some copper ores. Major producers are China, Russia, and the United States.
Extraction and Production
- Byproduct: From zinc ore processing and coal fly ash
- Zone Refining: For high-purity semiconductor-grade material
- Sources: Zinc production residues, coal combustion
- Global production: about 130 tons annually
Applications and Uses
Electronics and Optics
- Fiber optics (germanium-doped silica)
- Infrared optics (lenses, windows)
- Solar cells (multi-junction cells)
- Semiconductor devices (SiGe technology)
Specialty Applications
- Gamma-ray spectroscopy (HPGe detectors)
- Night vision systems
- Thermal imaging cameras
- Satellite solar panels
Catalysts
- PET plastic production
- Polymerization catalysts
Historical Use
- First transistor (1947) used germanium
- Early semiconductor era dominated by germanium before silicon
Biological Role
Germanium has no known essential biological role. Some organic germanium compounds are marketed as supplements but have no proven benefits.
In the Human Body
Germanium is not normally present in significant amounts. Some dietary intake occurs from plants and water.
Health Claims
Organic germanium supplements are marketed with various health claims, but these are not supported by scientific evidence. Inorganic germanium compounds can be toxic.
Safety and Hazards
Toxicity
Elemental germanium has low toxicity. Germanium dioxide and organic germanium compounds can be toxic to kidneys with chronic high-dose exposure.
Handling Precautions
- Germanium dust may irritate respiratory system
- Some germanium compounds are toxic
- Handle germanium tetrachloride with care (corrosive)
- Standard semiconductor handling procedures apply
Environmental Impact
Germanium is rare and production volumes are low. Mining byproduct status limits dedicated environmental impacts.
Interesting Facts
- The first working transistor (1947) used germanium, launching the electronics age
- Germanium's properties were predicted by Mendeleev 15 years before its discovery
- Germanium is transparent to infrared light, making it ideal for thermal imaging
- Silicon eventually replaced germanium in most semiconductor applications
- Germanium is one of the few substances that expands when solidifying