Mo
Molybdenum
Element 42 · Transition metal
Molybdenum (Mo)
Molybdenum is a silvery metal with one of the highest melting points of all elements. It strengthens steel at high temperatures.
- Transition metal
- Period 5
- Group 6
- d-block
- solid at room temperature
Key properties
- Atomic mass
- 95.95
- u
- Electron configuration
- [Kr] 4d5 5s1
- Melting point
- 2,622.9 °C
- 2,896 K
- Boiling point
- 4,638.9 °C
- 4,912 K
- Density
- 10.2 g/cm³
- Electronegativity
- 2.16
- Pauling
- Atomic radius
- 209 pm
- van der Waals
- 1st ionisation energy
- 7.092 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about molybdenum
- 01
Molybdenum steel was used in World War I tank armour.
- 02
Nitrogen-fixing bacteria need molybdenum to turn air into fertiliser.
- 03
Molybdenum disulfide is a slippery solid lubricant, much like graphite.
Applications
What is molybdenum used for?
- Alloy and stainless steel
- Catalysts in oil refining
- Lubricants (MoS₂)
- Heating elements
History
Discovery & name origin
Discovered by
Year
Where
Sweden
Name origin
Greek molybdos, “lead” — its ore was confused with lead ore.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 42
- Atomic mass
- 95.95 u
- Group
- 6
- Period
- 5
- Block
- d-block
- Electron configuration
- [Kr] 4d5 5s1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d5
- Electrons per shell
- 2, 8, 18, 13, 1
- Electronegativity (Pauling)
- 2.16
- Electron affinity
- 0.746 eV
- Atomic radius (van der Waals)
- 209 pm
- Stable isotopes
- 6
Oxidation states
Highlighted: common oxidation states (+6).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st684.3
- 2nd1,560
- 3rd2,618
- 4th4,480
- 5th5,257
- 6th6,640.8
- 7th12,125
- 8th13,860
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 2,896 K · 2,622.9 °C · 4,753.1 °F
- Boiling point
- 4,912 K · 4,638.9 °C · 8,381.9 °F
- Density
- 10.2 g/cm³
- Molar heat capacity
- 24.06 J/(mol·K)
- Appearance
- Grey metallic
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Molybdenum questions
What is Mo on the periodic table?
Mo is the symbol for molybdenum, element 42 on the periodic table. It sits in group 6, period 5, in the transition metal category, and has an atomic mass of 95.95.
What is the atomic number of molybdenum?
Molybdenum has atomic number 42, so every molybdenum atom has 42 protons in its nucleus. Its symbol is Mo and its atomic mass is 95.95.
Who discovered molybdenum?
Molybdenum was discovered by Carl Wilhelm Scheele in 1778 (Sweden). The name comes from Greek molybdos, “lead” — its ore was confused with lead ore.
What is molybdenum used for?
Molybdenum is used for: alloy and stainless steel; catalysts in oil refining; lubricants (MoS₂); heating elements.
Is molybdenum a metal?
Yes. Molybdenum is a transition metal, one of the metallic elements.
What is the electron configuration of molybdenum?
The electron configuration of molybdenum is [Kr] 4d5 5s1. Its 42 electrons are arranged in shells as 2, 8, 18, 13, 1.