Mn · Element 25 · Transition metal
Essential in trace amounts, brittle in bulk, and the reason your steel does not shatter in the cold.
Structure
Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.
Measured values
Every bar shows where manganese sits among all 118 elements for that property.
Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.
Same element, different neutrons
All manganese atoms have the same number of protons, 25, and differ only in their number of neutrons: those variants are its isotopes. The most common, Mn-55, has 30 neutrons and makes up 100% of natural manganese.
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| Mn-54 | 29 | — | 312.20 days | ε/β⁺ |
| Mn-55 most common | 30 | 100% | Stable | — |
Here the classroom shortcut, rounded atomic mass (54.938) minus atomic number, gives the same answer: 30.
Decay modes
Data: IAEA Nuclear Data Section, LiveChart of Nuclides, ground-state evaluations, retrieved October 10, 2026. Abundance is the share of atoms in the natural element; a dash means the isotope has no standard natural abundance.
Size, to scale
Radius 127 pm — that is 0.127 nm, so about 3.94 million of them side by side would span a millimetre.
Thermal range
Manganese is liquid over a 815 K window, from 1519 K to 2334 K.
The story
Manganese (Mn) is element 25, a hard, brittle, silvery-gray transition metal in group 7. It melts at 1,246 °C (1,519 K) and has a density of 7.21 g/cm³. It is the twelfth most abundant element in Earth's crust and is essential both to steelmaking and to living things.
Manganese has 25 electrons in four shells, arranged 2, 8, 13, 2, with the configuration [Ar] 3d⁵ 4s². Its common oxidation states are +2, +4 and +7, which give it compounds of many colors: pale pink Mn²⁺ salts, brown-black manganese dioxide (+4) and the deep purple permanganate ion (+7).
Natural manganese consists of a single stable isotope, manganese-55. Manganese-53, with a half-life of 3.7 million years, is used to date meteorites.
The mineral pyrolusite, manganese dioxide, was used as a black pigment in prehistoric cave paintings and later by glassmakers to remove color from glass. It was called black magnesia, after the Magnesia region of Greece, and was long confused with magnetic iron ore.
In 1774 Carl Wilhelm Scheele showed that pyrolusite contained a new element. The same year his friend Johan Gottlieb Gahn isolated the impure metal by heating pyrolusite with charcoal.
The name manganese comes, through Italian, from magnesia, the same source as the name of magnesium.
Applications
About 90% of manganese goes into steel. It removes oxygen and binds sulfur, which would otherwise make steel brittle, and it increases strength and hardness. Most steels contain under 1% manganese. Hadfield steel, with about 12 to 14%, hardens under impact and is used for rail crossings, rock crushers and excavator teeth.
Where it comes from
950 mg/kg of Earth's crust · more abundant than 90% of elements
Manganese makes up about 0.1% of Earth's crust. It occurs in many minerals, and large areas of the deep ocean floor are covered with ferromanganese nodules and crusts, which also contain nickel, copper and cobalt.
South Africa holds about 70% of the world's known manganese resources, mostly in the Kalahari manganese field, and mines the most manganese, followed by Gabon, Ghana and Australia (USGS).
Handling
Manganese is an essential nutrient. It activates many enzymes, including manganese superoxide dismutase, and in plants a cluster of four manganese atoms splits water to release oxygen during photosynthesis.
Breathing manganese dust or fumes over months or years, as in some mining, smelting and welding work, can cause manganism, a nerve disorder with symptoms similar to Parkinson's disease. High levels in drinking water may also affect children's development. Potassium permanganate is a strong oxidizer that can burn the skin and start fires with combustible materials.
Quick answers
Manganese (symbol Mn) is element 25 on the periodic table, a transition metal in period 4, group 7. Essential in trace amounts, brittle in bulk, and the reason your steel does not shatter in the cold. At room temperature it is a solid.
[Ar] 3d⁵ 4s², giving 4 occupied shells with the distribution 2, 8, 13, 2.Manganese melts at 1519 K (1245.9 °C) and boils at 2334 K (2060.9 °C).
The standard atomic weight of manganese is 54.938 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.
The most common manganese atom, Mn-55, has 30 neutrons: its mass number, 55, minus its atomic number, 25. It makes up 100% of natural manganese. The classroom shortcut, rounded atomic mass (54.938) minus atomic number, gives the same 30.
Manganese has a density of 7.21 g/cm³. Water is 1.0 g/cm³, so a block of manganese is about 7.2× heavier.
Manganese has a Pauling electronegativity of 1.55. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). Values in this middle band tend to form covalent rather than strongly ionic bonds.
Manganese was discovered in 1774 by Johan Gottlieb Gahn. Origin of the name: Latin magnes, "magnet".
Manganese makes up about 950 mg/kg of the Earth's crust — common enough to be mined at scale.