Osmium (symbol Os, atomic number 76) is the densest naturally occurring element, used in hard, wear-resistant tips. It is classified as a transition metal and sits in group 8, period 6 of the periodic table.
Overview
Osmium is the chemical element with atomic number 76 and the symbol Os. With a standard atomic weight of 190.23, it is a transition metal. In the periodic table it occupies group 8 and period 6, and under standard conditions it is normally a solid. Osmium is the densest naturally occurring element, used in hard, wear-resistant tips.
Atomic structure
An atom of Osmium has 76 protons in its nucleus and, when neutral, 76 electrons arranged in the configuration [Xe] 4f14 5d6 6s2. Its standard atomic weight of 190.23 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Osmium was discovered in 1803 by Smithson Tennant. It follows Rhenium (Re) and precedes Iridium (Ir) in order of atomic number.
| Atomic number | 76 |
|---|---|
| Symbol | Os |
| Atomic mass | 190.23 |
| Category | Transition metal |
| Group | 8 |
| Period | 6 |
| Electron configuration | [Xe] 4f14 5d6 6s2 |
| Phase at STP | Solid |
| Discovered | 1803 (Smithson Tennant) |