Manganese
transition metalProperties
| Property | Value |
|---|---|
| Atomic Mass | 54.938 amu |
| Category | transition metal |
| Group | 7 |
| Period | 4 |
| Electron Configuration | 1s2 2s2 2p6 3s2 3p6 3d5 4s2 |
| Electronegativity | 1.55 (Pauling) |
| Oxidation States | 7, 4, 3, 2 |
| Melting Point | 1519 K (1245.8 °C) |
| Boiling Point | 2334 K (2060.8 °C) |
| Density | 7.21 g/cm³ |
| Discovered By | Johan Gottlieb Gahn (1774) |
About Manganese
Manganese is the transition metal whose colors give it away: pink Mn²⁺ in solution, brown MnO₂ that coats old battery cathodes, deep purple permanganate (MnO₄⁻) sitting in just about every undergrad lab. That color range is a direct readout of how many oxidation states it can occupy — every integer from +2 through +7, which is unusual even by 3d-block standards and traces back to the half-filled 3d⁵ 4s² configuration. About 90% of mined Mn ends up in steelmaking, where it scavenges sulfur and oxygen during smelting and ends up as an alloying element. Hadfield steel (around 13% Mn) work-hardens dramatically under impact, which is why it has been the standard for rock-crusher jaws and railway switch frogs since 1882. Biologically, Mn is the metal at the heart of the oxygen-evolving complex in photosystem II — a Mn₄CaO₅ cluster that splits two water molecules into O₂, four protons, and four electrons every time a plant photosynthesizes. The free oxygen in Earth's atmosphere passed through that cluster.
Fun Fact
The oxygen you are breathing right now was released by an enzyme that depends on manganese — photosystem II in plants uses a cluster of four manganese atoms to split water molecules, generating all the free oxygen in Earth's atmosphere.
Common Uses
- Steel deoxidizer and alloying element (~90% of supply)
- MnO₂ cathode in alkaline and zinc-carbon dry cells
- Potassium permanganate as oxidant and water-treatment reagent
- Hadfield steel (~13% Mn) for rail crossings and crusher jaws
- Glass decolorizer that masks green tints from iron impurities