The arsenate is an ion with the chemical formula AsO3−4. 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. Resonance disperses the ion's −3 charge across all four oxygen atoms.
Adamite, a naturally occurring arsenate mineral.
Pourbaix diagram showing the distribution of arsenate and arsenite species in water. Oxygenated waters have a high pe value and arsenate species dominate. In deoxygenated water, with low pe, arsenite species dominate.
Arsenic is a chemical element; it has symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is a notoriously toxic heavy metal. It occurs naturally in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.
Arsenic
A large sample of native arsenic from Sainte-Marie-aux-Mines, France
Realgar
The arsenic labyrinth, part of Botallack Mine, Cornwall
