Germanium (Ge)

Grayish-white metalloid

Germanium was the original semiconductor before silicon took over, now used in fiber optics and infrared lenses, and with [Ar] 3d¹⁰ 4s² 4p², germanium has a bandgap of 0.67 eV and was used in the first transistor (1947). It is transparent to infrared radiation and used in night-vision optics.

Key metrics

Density5.32g/cm³

Melting point1,211K

Boiling point3,106K

Electronegativity2.01Pauling

Discovery

1886discovered

Discovered by: Clemens Winkler
Reactivity profile: Stable at room conditions
Reactivity: Low
Bonding: Covalent

Electron configuration

\textcolor{#6b7280}{[Ar]}\; \textcolor{#22c55e}{3_{d}^{10}}\; \textcolor{#ef4444}{4_{s}^{2}}\; \textcolor{#3b82f6}{4_{p}^{2}}

[Ar] 3d10 4s2 4p2

Wave function

\Psi_{\text{Ge}} \approx \frac{1}{\sqrt{32!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{32}(\mathbf{r}_{32}) \right|

Probability density $|\Psi|^2$ across the Ge valence shell.

Crystal structure

Diamond Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number4

Atoms per cell8

Atomic packing factor0.34

Physical properties

Atomic radius: 125 pm
Ionization energy: 762 kJ/mol
Electron affinity: 119 kJ/mol
Crystal structure: Diamond cubic

Oxidation states

+2+4

Acid/base

Can act as acid or base

Strongly acidicStrongly basic

State at 25 °CSolid

1211 K3106 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

422.7nmGe I (blue)Violet100%

468.5nmGe IBlue60%

565.7nmGe I (yellow)Yellow40%

Dominant line 422.7 nmRange 423–566 nmTransitions 3