Valency of Copper (Cu)
Copper shows variable valency — most commonly 1 and 2 — 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 Copper. 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 Copper page is one click away.
Counting the valence electrons
From the configuration [Ar] 3d¹⁰ 4s¹, Copper'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: Copper belongs to group 11 of the periodic table, period 4.
Why Copper has more than one valency
The common valencies are 1 and 2. Both the outer s electrons and the nearby (n−1)d electrons sit close in energy, so Copper can offer different numbers of them in different compounds — giving ions such as Cu¹⁺ and Cu²⁺ and families of compounds like Cu₁X₂ / CuX.
Valency vs valence electrons
Valence electrons are what you count (1 for Copper); valency is what the atom will do to complete its outer shell (1 and 2 here). Keep the two words straight and half the periodic-table chapter writes itself.
Students also ask
How do I find the valency of Copper from its group?
Copper sits in group 11; for this transition group the safe exam answer is its common valency, 1 and 2.
Why does Copper show variable valency?
Because both its outer shell and the nearby inner subshell can participate in bonding, Copper forms more than one stable ion — hence valencies 1 and 2.