Molybdenum

Molybdenum • Transition Metal

Primary XPS region: Mo3d
Overlapping regions: S2s
Binding energies of common chemical states:

Chemical state	Binding energy Mo3d_5/2
Mo metal	228.0 eV
MoO₂	229.5 eV
MoO₃	233.1 eV

Experimental information

S2s region strongly overlaps Mo3d when sulfur is present as sulfate.

Interpretation of XPS spectra

Mo3d peaks are asymmetric for molybdenum metal.
- Peaks are symmetric for Mo oxides.
Mo3d region has well separated spin-orbit components (Δ=3.15eV).

General comments

Multiple oxides observed (MoO, MoO₂, MoO₃).
- Argon sputtering reduces oxides to mixtures of lower oxidation state oxides and metal.

About this element

Symbol: Mo
Date of discovery: 1778
Name origin: Greek molubdos
Appearance: silverish
Discoverer: Carl Wilhelm Scheele
Obtained from: molybdenite, wulfenite

Melting point: 2890 K
Boiling point: 4885 K
Density[kg/m³]: 10280
Molar volume: 9.38 × 10^-6 m³/mol
Protons/Electrons: 42
Neutrons: 54
Shell structure: 2,8,18,13,1
Electron configuration: [Kr]4d55s1
Oxidation state: 2,3,4,5,6
Crystal structure: body centered cubic

Molybdenum, a silvery white, very hard, transition metal has one of the highest melting points of all pure elements. Until the eighteenth century, compounds of molybdenum were mistaken as other elements, such as lead. In fact, the element is named after the Greek molubdos, meaning "leadlike". Molybdenum was rarely used until the turn of the twentieth century when a French company, Schneider and Co., discovered it as a beneficial alloy agent in armor plates. Today, a large percentage of all molybdenum is used in notably high-strength alloys and high-temperature steels for aircrafts and missiles. Molybdenum also serves as a catalyst in the petroleum industry, extracting organic sulfurs from petroleum products. Equally important, molybdenum is necessary in plant nutrition and is found in certain enzymes, such as xanthene oxidase.