What Is Osmium?
Osmium, symbol Os and atomic number 76, belongs to the transition metals — the wide central block known for hardness and multiple oxidation states.
The densest naturally occurring element (22.59 g/cm³).
As a transition metal in Period 6 and Group 8 (Transition Metals), osmium's placement on the table reflects its electron configuration of [Xe] 4f¹⁴ 5d⁶ 6s², which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Osmium is located in Period 6, an unusually long row that includes the entire lanthanide series.
Within that row, osmium sits in Group 8 (Transition Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Osmium has an atomic mass of 190.230 u and a density of 22.59 g/cm³. Its melting point is 3033°C and its boiling point is 5012°C.
Osmium is malleable and ductile in its pure metallic form, and like other transition metals it can typically form more than one stable oxidation state.
Electron Configuration Explained
Osmium's electron configuration is [Xe] 4f¹⁴ 5d⁶ 6s², describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine osmium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Osmium was formally discovered in 1803, Tennant, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Osmium Used For?
Osmium's specific properties make it useful in several applications, including:
- Fountain pen tips
- Phonograph needles
- Electrical contacts
- Alloy hardening
- Chemical catalysts
These uses reflect osmium's underlying classification as a transition metal, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Osmium
- A cube of osmium 10cm × 10cm × 10cm weighs 22.59 kg — densest natural element.
- Osmium is element number 76 on the periodic table, in Period 6 and Group 8.
- Its standard atomic mass is 190.230 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Osmium's atomic number?
Osmium has atomic number 76.
What is Osmium's chemical symbol?
Osmium's symbol is Os.
What group and period is Osmium in?
Osmium is in Period 6, Group 8 (Transition Metals).
What is Osmium's atomic mass?
Osmium's standard atomic mass is 190.230 u.