What Is Ruthenium?
Ruthenium, symbol Ru and atomic number 44, belongs to the transition metals — the wide central block known for hardness and multiple oxidation states.
A rare, hard, silvery-white platinum group metal.
As a transition metal in Period 5 and Group 8 (Transition Metals), ruthenium's placement on the table reflects its electron configuration of [Kr] 4d⁷ 5s¹, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Ruthenium is located in Period 5, which continues the transition metal pattern seen in Period 4 but one principal shell further out.
Within that row, ruthenium 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
Ruthenium has an atomic mass of 101.07 u and a density of 12.37 g/cm³. Its melting point is 2334°C and its boiling point is 4150°C.
Ruthenium 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
Ruthenium's electron configuration is [Kr] 4d⁷ 5s¹, 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 ruthenium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Ruthenium was formally discovered in 1844, K. Klaus, 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 Ruthenium Used For?
Ruthenium's specific properties make it useful in several applications, including:
- Electrical contacts
- Catalysts
- Hard disk coatings
- Solar cells
- Jewelry alloys
These uses reflect ruthenium'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 Ruthenium
- Ruthenium is one of the rarest metals on Earth — only a few tons produced annually worldwide.
- Ruthenium is element number 44 on the periodic table, in Period 5 and Group 8.
- Its standard atomic mass is 101.07 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Ruthenium's atomic number?
Ruthenium has atomic number 44.
What is Ruthenium's chemical symbol?
Ruthenium's symbol is Ru.
What group and period is Ruthenium in?
Ruthenium is in Period 5, Group 8 (Transition Metals).
What is Ruthenium's atomic mass?
Ruthenium's standard atomic mass is 101.07 u.