Valency of Ruthenium (Ru)
Ruthenium shows variable valency — most commonly 2 and 4 — because it is a d-block element whose outer electrons can join bonding in more than one way.
Teachers call it "one fact, fully handled" — exactly what this page does for Ruthenium. The answer sits at the top in bold; scroll for the working, the shell-by-shell breakdown and the two questions students ask most. Need the whole picture instead — history, characteristics, uses, exam questions? The full Ruthenium page is one click away.
Counting the valence electrons
From the configuration [Kr] 4d⁷ 5s¹, Ruthenium's outermost shell carries 1 electron. For a d-block element the nearby inner "d" subshell can also lend electrons, which is where variable valency comes from.
Position check: Ruthenium belongs to group 8 of the periodic table, period 5.
Why Ruthenium has more than one valency
The common valencies are 2 and 4. Both the outer s electrons and the nearby (n−1)d electrons sit close in energy, so Ruthenium can offer different numbers of them in different compounds — giving ions such as Ru²⁺ and Ru⁴⁺ and families of compounds like RuX / Ru₄X₂.
Valency vs valence electrons
Valence electrons are what you count (1 for Ruthenium); valency is what the atom will do to complete its outer shell (2 and 4 here). Keep the two words straight and half the periodic-table chapter writes itself.
Students also ask
How do I find the valency of Ruthenium from its group?
Ruthenium sits in group 8; for this transition group the safe exam answer is its common valency, 2 and 4.
Why does Ruthenium show variable valency?
Because both its outer shell and the nearby inner subshell can participate in bonding, Ruthenium forms more than one stable ion — hence valencies 2 and 4.