Average mass of an atom in unified atomic mass units (1 u is 1/12 of the mass of a carbon-12 atom). Accounts for the natural mix of the element’s isotopes.
Number of the vertical column, 1 to 18 in IUPAC numbering. Elements in a group share the same outer-shell layout, so their properties are alike.
Number of the horizontal row. Usually equal to the number of electron shells in the atom; palladium is the exception, with four shells in period 5.
The subshell (s, p, d or f) that receives the last electrons in the usual filling order; it divides the table into four blocks. Real atoms sometimes differ: lanthanum starts the f-block but has no f electrons.
[Ar] 4s² 3d¹⁰ 4p²
How electrons are arranged in subshells. The bracket stands for the previous noble gas; the superscript is the number of electrons in a subshell.
2, 8, 18, 4
Number of electrons in each shell, from the nucleus outwards.
938.3 °C (1,211.4 K)
Temperature at which the solid turns liquid at standard pressure. Helium, carbon and arsenic do not melt at normal pressure: helium needs about 25 atm, carbon and arsenic turn straight into vapour.
2,833 °C (3,106 K)
Temperature at which the liquid boils at standard pressure. For carbon and arsenic, the temperature at which the solid turns straight into vapour (sublimation).
5.323 g/cm³
Mass of one cubic centimetre of the substance. For gases, at 0 °C and standard pressure.
2.01 Pauling
How strongly an atom pulls electrons towards itself in a chemical bond. On the Pauling scale it runs from 0.79 for caesium to 3.98 for fluorine.
7.899 eV
Energy needed to remove the most loosely bound electron from an atom. The lower it is, the more easily the element gives up an electron, which is typical of metals.
1.233 eV
Energy released when a neutral atom gains an electron. Highest for the halogens. Noble gases, nitrogen and some metals form no stable negative ion.
120 pm
Half the length of a single covalent bond between two atoms of the element. It shows the size of an atom inside a molecule or crystal: 76 pm for carbon, 132 pm for iron.
+4, +2, -4
Charges the atom would have in its compounds if all its bonds were ionic; the main ones are listed.
Germanium (Ge) is a chemical element with atomic number 32. It sits in group 14 and period 4 of the periodic table, in the p-block. It is a metalloid. At room temperature it is a solid. Its standard atomic weight is 72.630.
Origin of the name
In 1886 Clemens Winkler found a new element in argyrodite, a silver mineral from a mine near Freiberg in Saxony, and named it after his homeland, Germany (Latin Germania). It was the ‘eka-silicon’ that Dmitri Mendeleev had predicted years before in the gap between silicon and tin. Winkler first wanted to call it neptunium, because the planet Neptune too had been predicted before it was seen, but that name was already taken.
Where is germanium found?
Germanium is rare and almost never concentrated in ores of its own. It is recovered as a by-product, mainly from zinc ores and from the ash of certain coals.
What is germanium used for?
The first transistors and diodes were made of germanium, until silicon took its place. Today germanium goes into optical fibres, and because it lets infrared light through, its lenses are used in night-vision devices and thermal cameras.