Formal Oxidation States For Pyrite, Marcasite, and Arsenopyrite
From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite is probably best described as Fe2+S22ā. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear SāS bonds. These persulfide units can be viewed as derived from hydrogen disulfide, H2S2. Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite, MoS2, features isolated sulfide (S2ā) centers because the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Whereas pyrite has S2 subunits, arsenopyrite has AsS units, formally derived from deprotonation of H2AsSH. Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+(AsS)3ā.
Read more about this topic: Pyrite
Famous quotes containing the words formal and/or states:
“There must be a profound recognition that parents are the first teachers and that education begins before formal schooling and is deeply rooted in the values, traditions, and norms of family and culture.”
—Sara Lawrence Lightfoot (20th century)
“I cannot say what poetry is; I know that our sufferings and our concentrated joy, our states of plunging far and dark and turning to come back to the world—so that the moment of intense turning seems still and universal—all are here, in a music like the music of our time, like the hero and like the anonymous forgotten; and there is an exchange here in which our lives are met, and created.”
—Muriel Rukeyser (1913–1980)