Germanium

Germanium (Ge) is a metalloid with atomic number 32 and an atomic mass of 72.63. Its electron configuration is [Ar] 3d10 4s2 4p2, which gives it 4 valence electrons.

Germanium key data

Symbol	Ge
Atomic number	32
Atomic mass (standard atomic weight)	72.63
Molar mass	72.63 g/mol
Protons	32
Neutrons (most abundant isotope, germanium-74)	42
Electrons (neutral atom)	32
Valence electrons	4
Category	Metalloid
Period	4
Group	14
Block	p-block
Noble gas notation	[Ar] 3d10 4s2 4p2
Full electron configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p2
Electrons per shell	2, 8, 18, 4

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

Measured properties of germanium

From PubChem, the US National Institutes of Health. Public domain. The electron affinity is the measured value for germanium, from Wikipedia’s electron affinity data page, in place of PubChem’s 1.35 eV.

Melting point	1211.4 K (938.25 °C), 50th of 103 by melting point
Boiling point	3106 K (2832.9 °C), 41st of 93 by boiling point
Density	5.323 g/cm³, 61st of 96 by density
State at room temperature	Solid
Electronegativity	2.01 (Pauling), 30th of 95 by electronegativity
Van der Waals radius	211 pm, joint 44th of 99 by atomic radius
First ionisation energy	7.9 eV (762 kJ/mol), 35th of 102 by first ionisation energy
Electron affinity	1.2327 eV (118.94 kJ/mol), 17th of 57 by electron affinity
Common oxidation states	+4, +2
Discovered	1886

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Germanium electron configuration

The full electron configuration of germanium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p2. With the noble-gas core collapsed it is [Ar] 3d10 4s2 4p2, and the outermost subshell is 4p2.

Bohr model of germanium (Ge): a nucleus and four shells holding 2, 8, 18 and 4 electrons from the inside out. — Bohr model of germanium (Ge). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Orbital box diagram of germanium (Ge), 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p2: one box per orbital, filled by Hund’s rule, showing two unpaired electrons, in 4p. — Orbital diagram of germanium (Ge). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one germanium atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

one atom = 72.63 / (6.02214076 × 10²³)
= 1.2060 × 10⁻²² g

Atoms in one gram

atoms per gram = 6.02214076 × 10²³ / 72.63
= 8.2915 × 10²¹ atoms

Germanium on the periodic table

Germanium is in period 4, group 14, in the p-block.

The other elements of group 14 are carbon, silicon, tin, lead and flerovium.