About

Germanium is a lustrous, hard, grayish-white metalloid. As an important semiconductor, it was a key material in early transistors before being largely replaced by silicon. Today, it is primarily used in fiber-optic systems to increase refractive index, in infrared optics for thermal imaging cameras, and as a polymerization catalyst. It is also used in some high-efficiency solar cells.

Atomic Properties

Atomic Number32

Atomic Weight72.63 u

Neutrons (common)41

Electron Configuration[Ar] 3d¹⁰ 4s² 4p²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p²

Electrons per Shell2, 8, 18, 4

Electronegativity2.01

Electron Affinity119 kJ/mol

Oxidation States+4, +2, +1, -4

Covalent Radius122 pm

Van der Waals Radius211 pm

Ionic Radius53 pm

Periodic Table Position

Group14

Period4

BlockP

Chemical SeriesMetalloids

Physical Properties

State at STPsolid

Appearancegrayish-white

Crystal Structurediamond cubic

Magnetic Orderingdiamagnetic

Speed of Sound5,400 m/s

Poisson Ratio0.26

Thermal Properties

Melting Point1,211.4 K

Boiling Point3,106 K

Thermal Expansion0 1/K

Thermal Conductivity60.2 W/(m·K)

Specific Heat0.32 J/(g·K)

Molar Heat23.222 J/(mol·K)

Heat of Fusion36.94 kJ/mol

Heat of Vaporization334 kJ/mol

Abundance

In Earth's Crust1.5 ppm

In Ocean0 ppm

In Solar System0.2 ppm

In Universe2 ppm

Discovery

Discovered byClemens Winkler

Discovery Year1,886

Occurrenceprimordial

CAS Number7440-56-4

Electron Configuration

Energy

↿⇂

↿

Isotopes of Germanium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
⁶⁸Ge	67.928094	—	271.05 d	Electron Capture
⁶⁹Ge	68.927965	—	39.05 h	Positron Emission, Electron Capture
⁷⁰Ge	69.924250	20.57%	Stable	Stable
⁷¹Ge	70.924951	—	11.43 d	Electron Capture
⁷²Ge	71.922080	27.45%	Stable	Stable
⁷³Ge	72.923460	7.75%	Stable	Stable
⁷⁴Ge	73.921180	36.5%	Stable	Stable
⁷⁶Ge	75.921400	7.73%	1.88 Zy	Double Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Germanium in our interactive viewer.

View 3D Model of Germanium