Mo 42

Molybdenum (Mo)

transition-metal

Period: 5 Group: 6 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Kr] 5s¹ 4d⁵

Melting point

2622.85 °C (2896 K)

Boiling point

4638.85 °C (4912 K)

Density

1.020000e+4 kg/m³

Oxidation states

−4, −2, −1, 0, +1, +2, +3, +4, +5, +6

Electronegativity (Pauling)

2.16

Ionization energy (1st)

Discovery year

1778

Atomic radius

145 pm

Details

Name origin Greek: molybdos (lead).

Discovery country Sweden

Discoverers Carl Wilhelm Scheele

Molybdenum is a hard refractory transition metal of group 6. It is notable for its high melting point, useful alloying behavior, and rich redox chemistry. In nature it occurs mainly as molybdenite, and industrially it is important in steels, superalloys, catalysts, and lubricating sulfide materials. In biology, molybdenum is an essential trace element because several enzymes use molybdenum cofactors for oxygen-atom transfer and related redox reactions.

The metal is silvery white, very hard, but is softer and more ductile than tungsten. It has a high elastic modulus, and only tungsten and tantalum, of the more readily available metals, have higher melting points. It is a valuable alloying agent, as it contributes to the hardenability and toughness of quenched and tempered steels. It also improves the strength of steel at high temperatures.

The name derives from the Greek molybdos for "lead". The ancients used the term "lead" for any black mineral that leaves a mark on paper. Molybdenum was discovered by the Swedish pharmacist and chemist Carl Wilhelm Scheele in 1778. It was first isolated by the Swedish chemist Peter-Jacob Hjelm in 1781.

Molybdenum was discovered by Carl Welhelm Scheele, a Swedish chemist, in 1778 in a mineral known as molybdenite (MoS2) which had been confused as a lead compound. Molybdenum was isolated by Peter Jacob Hjelm in 1781. Today, most molybdenum is obtained from molybdenite, wulfenite (PbMoO4) and powellite (CaMoO4). These ores typically occur in conjunction with ores of tin and tungsten. Molybdenum is also obtained as a byproduct of mining and processing tungsten and copper.

From the Greek word molybdo, lead. Before Scheele recognized molybdenite as a distinct ore of a new element in 1778, it was confused with graphite and lead ore. The metal was prepared in impure form in 1782 by Hjelm. Molybdenum does not occur natively, but is obtained principally from molybdenite. Wulfenite, and Powellite are also minor commercial ores.

Read about Molybdenum on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 145 pm

Covalent radius 154 pm

Van der Waals radius 209 pm

Metallic radius 130 pm

Density

Molar volume 0.0094 L/mol

Phase at STP solid

Melting point 2622.85 °C

Boiling point 4638.85 °C

Specific heat capacity 0.251 J/(g·K)

Molar heat capacity 24.06 J/(mol·K)

Crystal structure bcc

Chemical

Electronegativity (Pauling) 2.16

Electronegativity (Allen) 1.47

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −4, −2, −1, 0, +1, +2, +3, +4, +5, +6

Valence electrons 6

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.29020055 eV

Heat of vaporization 5.088874 eV

Heat of sublimation 6.819713 eV

Heat of atomization 6.819713 eV

Atomization enthalpy

Nuclear

Stable isotopes 6

Discovery year 1778

Abundance

Abundance (Earth's crust) 1.2 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 315 pm

Electronic Structure

Electrons per shell 2, 8, 18, 13, 1

Identifiers

CAS number 7439-98-7

Term symbol

InChI InChI=1S/Mo

InChI Key ZOKXTWBITQBERF-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 42

Electrons 42

Charge Neutral

Configuration Mo: 4d⁵ 5s¹

[Kr] 4d⁵ 5s¹

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s¹

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

6/6

↑

1/2 1↑

↑

5/10 5↑

Total electrons: 42 Unpaired: 6

Atomic model

Protons 42

Neutrons 54

Electrons 42

Mass number 96

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
94 Stable	93.9050849 ± 0.00000048	9.1500%	Stable
95 Stable	94.90583877 ± 0.00000047	15.8400%	Stable
96 Stable	95.90467612 ± 0.00000047	16.6700%	Stable
97 Stable	96.90601812 ± 0.00000049	9.6000%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 2597.8 °C below melting point (2622.85 °C)

Melting point 2622.85 °C

Boiling point 4638.85 °C

Below melting by 2597.8 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

2622.85 °C

Boiling point Literature

4638.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.29020055 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

5.088874 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

6.819713 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

1.020000e+4 kg/m³

At standard conditions

Current density Calculated

1.020000e+4 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 42 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Mo I	0	818	721	808
Mo II	+1	209	0	0
Mo III	+2	62	0	0
Mo IV	+3	29	0	0
Mo V	+4	966	923	929
Mo VI	+5	245	245	245
Mo VII	+6	413	0	413
Mo VIII	+7	109	0	109
Mo IX	+8	231	0	231
Mo X	+9	120	0	120

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Mo I	0	428
Mo II	+1	249
Mo III	+2	120
Mo IV	+3	81
Mo V	+4	258
Mo VI	+5	113
Mo VII	+6	96
Mo VIII	+7	77
Mo IX	+8	93
Mo X	+9	48

NIST Levels Holdings →

42 Mo 95.95

Molybdenum — Atomic Orbital Visualizer

[Kr]5s14d5

Energy levels 2 8 18 13 1

Oxidation states -4, -2, -1, 0, +1, +2, +3, +4, +5, +6

HOMO 5s n=5 · l=0 · m=0

Molybdenum — Atomic Orbital Visualizer Preview

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42 Mo 95.95

Molybdenum — Crystal Structure Visualizer

Body-Centered Cubic · Pearson cI2

Experimental

Pearson cI2

Coord. № 8

Packing 68.000%

Molybdenum — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+3	6	N/A	69 pm
+4	6	N/A	65 pm
+5	4	N/A	46 pm
+5	6	N/A	61 pm
+6	4	N/A	41 pm
+6	5	N/A	50 pm
+6	6	N/A	59 pm
+6	7	N/A	73 pm

Compounds

95.950 u

Mo+2

95.950 u

97.905 u

Mo+4

95.950 u

98.908 u

92.907 u

96.906 u

94.906 u

89.914 u

100.910 u

Mo+3

95.950 u

91.907 u

95.905 u

99.907 u

93.905 u

Isotopes (4)

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
94 Stable	93.9050849 ± 0.00000048	9.1500% ± 0.0900%	Stable	stable
95 Stable	94.90583877 ± 0.00000047	15.8400% ± 0.1100%	Stable	stable
96 Stable	95.90467612 ± 0.00000047	16.6700% ± 0.1500%	Stable	stable
97 Stable	96.90601812 ± 0.00000049	9.6000% ± 0.1400%	Stable	stable

94 Stable

Atomic mass (u) 93.9050849 ± 0.00000048

Natural abundance 9.1500% ± 0.0900%

Half-life Stable

Decay mode

stable

95 Stable

Atomic mass (u) 94.90583877 ± 0.00000047

Natural abundance 15.8400% ± 0.1100%

Half-life Stable

Decay mode

stable

96 Stable

Atomic mass (u) 95.90467612 ± 0.00000047

Natural abundance 16.6700% ± 0.1500%

Half-life Stable

Decay mode

stable

97 Stable

Atomic mass (u) 96.90601812 ± 0.00000049

Natural abundance 9.6000% ± 0.1400%

Half-life Stable

Decay mode

stable

Spectral Lines

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
382.2548 nm	290	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3P*	Measured	NIST
383.9084 nm	360	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3P*	Measured	NIST
386 nm	N/A	ID 915	emission	1s.5s 3S → 1s.5p 3P*	Measured	NIST
393.8911 nm	1400	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3P*	Measured	NIST
394.8336 nm	50	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 1F*	Measured	NIST
400.9437 nm	35	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 1D*	Measured	NIST
403.6485 nm	40	Mo VI	emission	4p6.7f 2F* → 4p6.8g 2G	Measured	NIST
405.4556 nm	50	Mo VI	emission	4p6.7f 2F* → 4p6.8g 2G	Measured	NIST
406.1547 nm	210	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3P*	Measured	NIST
406.2019 nm	15000	Mo VI	emission	4p6.7p 2P* → 4p6.7d 2D	Measured	NIST
406.4706 nm	14	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 1D*	Measured	NIST
406.527 nm	3500	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3F*	Measured	NIST
407.1568 nm	2800	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 1F*	Measured	NIST
407.4773 nm	3100	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3F*	Measured	NIST
416.4901 nm	75	Mo VI	emission	4p6.6g 2G → 4p6.7f 2F*	Measured	NIST
418.4284 nm	60	Mo VI	emission	4p6.6g 2G → 4p6.7f 2F*	Measured	NIST
418.6616 nm	2700	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3D*	Measured	NIST
422.59 nm	N/A	ID 896	emission	2p 2P* → 2s 2S	Measured	NIST
423.2026 nm	40000	Mo VI	emission	4p6.7p 2P* → 4p6.7d 2D	Measured	NIST
427.2928 nm	100	Mo VI	emission	4p6.7p 2P* → 4p6.7d 2D	Measured	NIST
433.4926 nm	840	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3D*	Measured	NIST
436 nm	N/A	ID 915	emission	1s.4p 3P* → 1s.4d 3D	Measured	NIST
438.442 nm	2900	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3D*	Measured	NIST
439.9605 nm	28	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3D*	Measured	NIST
446.6307 nm	79	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 1D*	Measured	NIST
447.4143 nm	63	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3F*	Measured	NIST
454.3076 nm	570	Mo V	emission	4p6.4d.(2D<3/2>).6s 2[3/2] → 4p6.4d.6p 3F*	Measured	NIST
462.464 nm	840	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 1D*	Measured	NIST
463.7675 nm	41	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3F*	Measured	NIST
466.0971 nm	100	Mo VI	emission	4p6.5f 2F* → 4p6.6d 2D	Measured	NIST
468.7277 nm	22	Mo V	emission	4p6.4d.(2D<5/2>).6s 2[5/2] → 4p6.4d.6p 3D*	Measured	NIST
474.6519 nm	8000	Mo VI	emission	4p6.5f 2F* → 4p6.6d 2D	Measured	NIST
504.622 nm	N/A	Mo VI	emission	4p6.7g 2G → 4p6.8h 2H*	Measured	NIST
504.622 nm	N/A	Mo VI	emission	4p6.7g 2G → 4p6.8h 2H*	Measured	NIST
524.749 nm	N/A	Mo VI	emission	4p6.7h 2H* → 4p6.8i 2I	Measured	NIST
524.749 nm	N/A	Mo VI	emission	4p6.7h 2H* → 4p6.8i 2I	Measured	NIST
527.675 nm	N/A	Mo VI	emission	4p6.7i 2I → 4p6.8k 2K*	Measured	NIST
527.675 nm	N/A	Mo VI	emission	4p6.7i 2I → 4p6.8k 2K*	Measured	NIST
558.5 nm	200	Mo VI	emission	4p6.8d 2D → 4p6.8f 2F*	Measured	NIST
562 nm	350	Mo VI	emission	4p6.8d 2D → 4p6.8f 2F*	Measured	NIST
587.138 nm	300	Mo VI	emission	4p6.7d 2D → 4p6.8p 2P*	Measured	NIST
603.562 nm	10	Mo VI	emission	4p6.4f 2F* → 4p6.5d 2D	Measured	NIST
618.867 nm	1400	Mo VI	emission	4p6.4f 2F* → 4p6.5d 2D	Measured	NIST
633.604 nm	1000	Mo VI	emission	4p6.4f 2F* → 4p6.5d 2D	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Van der Waals Radii

Batsanov

Alvarez

UFF

MM3

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆ (Gould–Bučko)

Miedema Parameters

Miedema molar volume

Miedema electron density

Supply Risk & Economics

Production concentration

Relative supply risk

Reserve distribution

Political stability (top producer)

Political stability (top reserve)

Phase Transitions & Allotropes

Melting point	2895.15 K
Boiling point	4912.15 K

Oxidation State Categories

−1 extended

+3 extended

−2 extended

+5 extended

0 extended

+4 main

+2 extended

+6 main

+1 extended

−4 extended

Advanced Reference Data

Screening Constants (10)

n	Orbital	σ
1	s	0.8744
2	p	4.0282
2	s	11.1232
3	d	14.7717
3	p	16.5264
3	s	16.0185
4	d	30.6076
4	p	27.0232
4	s	25.9036
5	s	35.894

Crystal Radii Detail (8)

Charge	CN	r_crystal (pm)	Origin
3	VI	83	estimated,
4	VI	79	from r^3 vs V plots, from metallic oxides,
5	IV	60	from r^3 vs V plots,
5	VI	75	from r^3 vs V plots,
6	IV	55	from r^3 vs V plots,
6	V	64
6	VI	73	from r^3 vs V plots,
6	VII	87

Isotope Decay Modes (58)

Isotope	Mode	Intensity
81	B+	—
81	B+p	—
82	B+	—
82	B+p	—
83	B+	100%
83	B+p	—
84	B+	100%
84	B+p	—
85	B+	100%
85	B+p	0.1%

X‑ray Scattering Factors (909)

Energy (eV)	f₁	f₂
10	—	2.2382
10.1447	—	2.20464
10.3088	—	2.17288
10.4756	—	2.14408
10.645	—	2.11566
10.8172	—	2.09307
10.9921	—	2.12057
11.1699	—	2.20711
11.3506	—	2.32651
11.5342	—	2.50051

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

1.2 milligrams per kilogram

References (1)

[5] Molybdenum https://education.jlab.org/itselemental/ele042.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

1×10-2 milligrams per liter

References (1)

[5] Molybdenum https://education.jlab.org/itselemental/ele042.html

Sources

Sources of this element.

Molybdenum is also recovered as a by-product of copper and tungsten mining operations. The metal is prepared from the powder made by the hydrogen reduction of purified molybdic trioxide or ammonium molybdate.

References (1)

[6] Molybdenum https://periodic.lanl.gov/42.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Molybdenum

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Molybdenum

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Molybdenum

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Molybdenum

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Molybdenum

This section provides all form of data related to element Molybdenum.

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9 PubChem Elements

Molybdenum

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.