42 - Molybdenum transition metal
Discovered by Carl Scheele in 1778
Molybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele.
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 13 | 2 in 4s + 6 in 4p + 5 in 4d |
| 5 | 1 | 1 in 5s |
gray metallic Appearance
96 u Atomic Mass
1.45 Å Atomic Radius
4.91k K Boiling Point
6 Group
4, 6 Common Oxidation States
1.54 Å Covalent Radius
10.3 g/cm³ Density
72.1 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d5 Electron Configuration
[Kr] 4d5 5s1 Electron Configuration (semantic)
2.16 Electronegativity
42 Electrons
7.09 eV First Ionization Energy
2, 3, 4, 5, 6 ICSD Oxidation States
684.3, 1560, 2618, 4480, 5257, 6640.8, 12125, 13860, 15835, 17980, 20190, 22219, 26930, 29196, 52490, 55000, 61400, 67700, 74000, 80400, 87000, 93400, 98420, 104400, 121900, 127700, 133800, 139800, 148100, 154500 kJ/mol Ionization Energies
2.89k K Melting Point
56 Mendeleev Number
24.1 J/(mol·K) Molar Heat
5 Number of Shells
54 Neutrons
42 Atomic Number
20 Number of Isotopes
-2, -1, 1, 2, 3, 4, 5, 6 Oxidation States
5 Period
Solid Phase
42 Protons
2, 8, 18, 13, 1 Electron Shell Occupations