Manganese

Manganese (Mn) is a transition metal with atomic number 25 and an atomic mass of 54.938. Its electron configuration is [Ar] 3d5 4s2.

Manganese key data

Symbol	Mn
Atomic number	25
Atomic mass (standard atomic weight)	54.938
Molar mass	54.938 g/mol
Protons	25
Neutrons (most abundant isotope, manganese-55)	30
Electrons (neutral atom)	25
Category	Transition metal
Period	4
Group	7
Block	d-block
Noble gas notation	[Ar] 3d5 4s2
Full electron configuration	1s2 2s2 2p6 3s2 3p6 3d5 4s2
Electrons per shell	2, 8, 13, 2

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

Measured properties of manganese

From PubChem, the US National Institutes of Health. Public domain. PubChem’s periodic table gives no value for the rows not shown.

Melting point	1519 K (1245.9 °C), 39th of 103 by melting point
Boiling point	2334 K (2060.9 °C), 52nd of 93 by boiling point
Density	7.3 g/cm³, 44th of 96 by density
State at room temperature	Solid
Electronegativity	1.55 (Pauling), 52nd of 95 by electronegativity
Van der Waals radius	197 pm, joint 63rd of 99 by atomic radius
First ionisation energy	7.434 eV (717.3 kJ/mol), 45th of 102 by first ionisation energy
Common oxidation states	+7, +4, +3, +2
Discovered	1774

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.

Manganese electron configuration

The full electron configuration of manganese is 1s2 2s2 2p6 3s2 3p6 3d5 4s2. With the noble-gas core collapsed it is [Ar] 3d5 4s2, and the outermost subshell is 4s2.

Bohr model of manganese (Mn): a nucleus and four shells holding 2, 8, 13 and 2 electrons from the inside out. — Bohr model of manganese (Mn). 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 manganese (Mn), 1s2 2s2 2p6 3s2 3p6 3d5 4s2: one box per orbital, filled by Hund’s rule, showing five unpaired electrons, in 3d. — Orbital diagram of manganese (Mn). 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 manganese 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 = 54.938 / (6.02214076 × 10²³)
= 9.1227 × 10⁻²³ g

Atoms in one gram

atoms per gram = 6.02214076 × 10²³ / 54.938
= 1.0962 × 10²² atoms

Manganese on the periodic table

Manganese is in period 4, group 7, in the d-block.

The other elements of group 7 are technetium, rhenium and bohrium.