Arsenic is an element and not a chemical. It belongs to Group 15 (pnictogens) on the periodic table. Its chemical symbol is As, and it has an atomic number of 33. Arsenic occurs in many different forms, including elemental arsenic, inorganic arsenic compounds, and organic arsenic compounds.

Some common examples of inorganic arsenic compounds include:

- Arsenic trioxide (As2O3): This is the most common form of inorganic arsenic. It is a white powder that is used in the production of other arsenic compounds, as well as in some pesticides and wood preservatives.

- Arsenic pentoxide (As2O5): This is a white or yellow powder that is used in the production of other arsenic compounds, as well as in some herbicides and insecticides.

- Sodium arsenite (Na3AsO3): This is a white powder that is used in the production of other arsenic compounds, as well as in some herbicides and insecticides.

- Calcium arsenate (Ca3(AsO4)2): This is a white powder that is used in the production of other arsenic compounds, as well as in some herbicides and insecticides.

Some common examples of organic arsenic compounds include:

- Monomethylarsonic acid (MMA): This is a colorless liquid that is found in some plants and animals, as well as in some pesticides.

- Dimethylarsinic acid (DMA): This is a colorless liquid that is found in some plants and animals, as well as in some pesticides.

- Trimethylarsine (TMAs): This is a colorless gas that is found in some industrial processes, as well as in some pesticides.

- Tetramethylarsonium (TMAs+): This is a colorless liquid that is found in some industrial processes, as well as in some pesticides.