The arsenate ion has the formula AsO₄³⁻.Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms.The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry.The ion's 3- charge is dispersed across all four oxygen atoms through resonance.

Arsenate readily reacts with metals to form arsenate metal compounds. Arsenate is a moderate oxidizer and an electron acceptor, with an electrode potential of +0.56 V for its reduction to arsenite.Due to arsenic having the same valency and similar atomic radius to phosphorus, arsenate shares similar geometry and reactivity with phosphate. Arsenate can replace phosphate in biochemical reactions and is toxic to most organisms.[