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 3d⁵
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, 13, 2
Number of electrons in each shell, from the nucleus outwards.
1,246 °C (1,519 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.
2,061 °C (2,334 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).
7.3 g/cm³
Mass of one cubic centimetre of the substance. For gases, at 0 °C and standard pressure.
1.55 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.
7.434 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.
no stable negative ion
Energy released when a neutral atom gains an electron. Highest for the halogens. Noble gases, nitrogen and some metals form no stable negative ion.
139 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.
+7, +4, +3, +2
Charges the atom would have in its compounds if all its bonds were ionic; the main ones are listed.
Manganese (Mn) is a chemical element with atomic number 25. It sits in group 7 and period 4 of the periodic table, in the d-block. It is a transition metal. At room temperature it is a solid. Its standard atomic weight is 54.938.
Origin of the name
The name goes back to the Latin magnes. Since antiquity glassmakers had used a black mineral, now called pyrolusite, to clear their glass; it was known as black magnesia, and in the 16th century glassmakers were calling it manganesum, from which came manganese. The white magnesia later gave its name to magnesium, so the two elements share one root. In 1774 Carl Wilhelm Scheele recognised that pyrolusite contained a new element, and that same year Johan Gottlieb Gahn extracted the metal by heating the mineral with charcoal.
Where is manganese found?
The main ore of manganese is pyrolusite. Most of the world’s known manganese lies in South Africa, in the Kalahari manganese field. Huge numbers of manganese nodules cover parts of the deep ocean floor.
What is manganese used for?
Most manganese goes into steel: it takes oxygen and sulfur out of molten steel and makes the steel stronger and tougher, as in railway rails. Manganese dioxide is a key ingredient of ordinary dry-cell batteries, and the deep-purple potassium permanganate is a strong oxidiser, used in laboratories and to disinfect water.
Interesting facts
In photosynthesis, a small cluster of manganese atoms in plants splits water and releases the oxygen we breathe.
Manganese is an essential trace element for people, needed in milligram amounts.