Valency of Selenium (Se)
The valency of Selenium is 2 — it has 6 valence electrons, and it loses them to complete its outer shell.
This is the fast lane: one page, one fact, zero digressions. Read the quick answer, check the table, and if your exam needs the full derivation, the sections below walk through it step by step — in Bangla and English, like every page here. Need the whole picture instead — history, characteristics, uses, exam questions? The full Selenium page is one click away.
Counting the valence electrons
From the configuration [Ar] 3d^10 4s^2 4p^4, Selenium's outermost shell carries 6 electrons. These are the electrons shown as dots in electron-dot diagrams — the hands Selenium uses to hold other atoms.
Position check: Selenium belongs to group 16 of the periodic table, period 4. For main-group elements in groups 13–18, a quick rule is valency = group number − 10, which gives 6 here.
Valency vs valence electrons
Valence electrons are what you count (6 for Selenium); valency is what the atom will do to complete its outer shell (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 Selenium from its group?
Selenium sits in group 16; groups 13–17 follow valency = group − 10, giving 6 (though Selenium also shows 2).
Why does Selenium show a fixed valency?
Selenium has 6 valence electrons and reaches a complete outer shell in one consistent way, so its valency stays fixed at 2.