Chemical element · reference page

32Ge

Germanium

Germanium is element 32 (Ge), located in period 4, group 14 and the p block. At room temperature its reference phase is solid. Its electron configuration is [Ar] 3d10 4s2 4p2.

Atomic number32

Standard atomic weight72.630(8)

Group14

Period4

Blockp

Electron configuration[Ar] 3d10 4s2 4p2

Electronic structure

What controls its chemistry

Group 14 elements have four valence electrons. That makes covalent bonding especially important for the lighter members, while metallic character increases down the group.

For germanium, the electron configuration [Ar] 3d10 4s2 4p2 sets the number and energy of the valence electrons that participate in bonding. Structure and oxidation state then determine the properties of its materials and compounds.

Chemical forms

Compounds, ions and materials

Typical compounds include oxides, halides and hydrides. The lighter members can build strong covalent networks or chains, while the heavier elements show increasing metallic bonding and greater importance of the +2 oxidation state.

Physical behaviour

State and phase changes

The reference phase at room temperature is solid. The listed density is 5.323 g/cm³. The melting point is 1 211 K (938.3 °C). The boiling point is 3 106 K (2 833 °C). Pressure, purity and crystal structure can shift measured physical properties.

Occurrence and applications

Where germanium is found and used

In practice, germanium is encountered in fibre optics, semiconductors and infrared optics.

In practice

Examples of real uses

Fibre optics

Germanium is used in optical fibres or dopants that control transmission, amplification or infrared response.

Semiconductors

Compounds or doped forms of germanium are used to control electrical conduction in semiconductor devices.

Infrared optics

Germanium is used in materials that transmit, detect or manipulate infrared radiation.

Periodic position

What its neighbours tell us

Germanium is in period 4 and group 14. In the neighbourhood shown here, it lies between gallium and arsenic in the same period; silicon is above it and tin below it in the same group. These positions make it possible to compare atomic size, ionisation energy and bonding behaviour with nearby elements.

Reference data

Physical and atomic properties

Classificationmetalloid

Phase at room temperatureSolid

Electron shells2 · 8 · 18 · 4

Density5.323 g/cm³

Melting point1 211 K (938.3 °C)

Boiling point3 106 K (2 833 °C)

Pauling electronegativity2.01

First ionisation energy762 kJ/mol

Electron affinity118.9 kJ/mol

Values describe the element or neutral atom where applicable. Physical data can depend on allotrope, pressure and measurement conditions.

History

Discovery and identification

The discovery of germanium is associated with Clemens Winkler. Recognition of the element, isolation of a pure sample and assignment of its modern atomic number did not necessarily occur at the same time.

Isotopes and atomic weight

How isotope composition changes the numbers

The standard atomic weight is 72.630(8). This value refers to the isotopic composition of natural terrestrial material, not to the mass of one specific atom.

Germanium has at least one stable isotope. Different isotopes have the same number of protons and therefore the same element identity, but different neutron numbers and atomic masses.

Safety

Handling and exposure

The hazards associated with germanium depend on chemical form, dose and route of exposure. Pure germanium, its ions and its compounds can have very different biological and environmental effects, so safety data should be checked for the actual substance being handled.