Valency of Arsenic (As)
The valency of Arsenic is 3 — it has 5 valence electrons, and it loses them to complete its outer shell.
Looking for Arsenic's valency without wading through a whole chapter? Here is the direct answer first, then the tables and derivations examiners want to see. Every number on this page comes from the same engine that powers the interactive table. Need the whole picture instead — history, characteristics, uses, exam questions? The full Arsenic page is one click away.
Counting the valence electrons
From the configuration [Ar] 3d^10 4s^2 4p^3, Arsenic's outermost shell carries 5 electrons. These are the electrons shown as dots in electron-dot diagrams — the hands Arsenic uses to hold other atoms.
Position check: Arsenic belongs to group 15 of the periodic table, period 4. For main-group elements in groups 13–18, a quick rule is valency = group number − 10, which gives 5 here.
Valency vs valence electrons
Valence electrons are what you count (5 for Arsenic); valency is what the atom will do to complete its outer shell (3 here). Keep the two words straight and half the periodic-table chapter writes itself.
Students also ask
How do I find the valency of Arsenic from its group?
Arsenic sits in group 15; groups 13–17 follow valency = group − 10, giving 5 (though Arsenic also shows 3).
Why does Arsenic show a fixed valency?
Arsenic has 5 valence electrons and reaches a complete outer shell in one consistent way, so its valency stays fixed at 3.