Valency of Tin (Sn)
Tin shows variable valency — most commonly 2 and 4 — because it is a p-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 Tin. 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 Tin page is one click away.
Counting the valence electrons
From the configuration [Kr] 4d^10 5s^2 5p^2, Tin's outermost shell carries 4 electrons. These are the electrons shown as dots in electron-dot diagrams — the hands Tin uses to hold other atoms.
Position check: Tin belongs to group 14 of the periodic table, period 5. For main-group elements in groups 13–18, a quick rule is valency = group number − 10, which gives 4 here.
Why Tin 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 Tin can offer different numbers of them in different compounds — giving ions such as Sn²⁺ and Sn⁴⁺ and families of compounds like SnX / Sn₄X₂.
Valency vs valence electrons
Valence electrons are what you count (4 for Tin); 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 Tin from its group?
Tin sits in group 14; groups 13–17 follow valency = group − 10, giving 4 (though Tin also shows 2 and 4).
Why does Tin show variable valency?
Because both its outer shell and the nearby inner subshell can participate in bonding, Tin forms more than one stable ion — hence valencies 2 and 4.