Molybdenum (Mo) – element 42
Molybdenum is a chemical element with the symbol Mo and atomic number 42. It is a transition metal in group 6, period 5 of the periodic table (d-block), and is a solid at room temperature.
Molybdenum (Mo) has atomic number 42, atomic mass 95.95 u and electron configuration [Kr] 4d5 5s1.
Molybdenum facts
| Symbol | Mo |
|---|---|
| Atomic number | 42 |
| Atomic mass | 95.95 u (g/mol) |
| Category | transition metal |
| Group | group 6 |
| Period | 5 |
| Block | d-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d5 |
| Noble-gas notation | [Kr] 4d5 5s1 |
| Electrons per shell | 2, 8, 18, 13, 1 |
Bohr model and shells
Molybdenum has 42 electrons in 5 shells: 2, 8, 18, 13, 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 2896 K (2622.8 °C) |
|---|---|
| Boiling point | 4912 K (4638.9 °C) |
| Density | 10.28 g/cm³ |
| Electronegativity (Pauling) | 2.16 |
| Electron affinity | 72.1 kJ/mol |
| Ionization energies | 684.3, 1560, 2618 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 24.06 J/(mol·K) |
| Discovered by | Carl Wilhelm Scheele |
Use the atomic mass in the molar mass calculator for any formula containing Mo.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of molybdenum?
The atomic mass of molybdenum is 95.95 u, so one mole of molybdenum atoms weighs 95.95 g.
What is the electron configuration of molybdenum?
Molybdenum has 42 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁵, or [Kr] 4d⁵ 5s¹ in noble-gas notation. Electrons per shell: 2, 8, 18, 13, 1.
Is molybdenum a metal?
Yes. Molybdenum is a transition metal.
Where is molybdenum on the periodic table?
Molybdenum is in group 6, period 5, in the d-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.