Molybdenum (symbol Mo, atomic number 42) is a refractory metal that strengthens steel and catalyses petroleum refining. It is classified as a transition metal and sits in group 6, period 5 of the periodic table.
Overview
Molybdenum is the chemical element with atomic number 42 and the symbol Mo. With a standard atomic weight of 95.95, it is a transition metal. In the periodic table it occupies group 6 and period 5, and under standard conditions it is normally a solid. Molybdenum is a refractory metal that strengthens steel and catalyses petroleum refining.
Atomic structure
An atom of Molybdenum has 42 protons in its nucleus and, when neutral, 42 electrons arranged in the configuration [Kr] 4d5 5s1. Its standard atomic weight of 95.95 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Molybdenum was discovered in 1781 by Peter Jacob Hjelm. It follows Niobium (Nb) and precedes Technetium (Tc) in order of atomic number.
| Atomic number | 42 |
|---|---|
| Symbol | Mo |
| Atomic mass | 95.95 |
| Category | Transition metal |
| Group | 6 |
| Period | 5 |
| Electron configuration | [Kr] 4d5 5s1 |
| Phase at STP | Solid |
| Discovered | 1781 (Peter Jacob Hjelm) |