ARSENIC As      Z = 33

This element was probably first isolated by Albertus Magnus in the thirteenth century. Its name comes from the Greek arsenilon (yellow orpiment). Orpiment comes from auri pigmentum (gold pigment).

Ionization energies

AsI 9.8 eV, AsII 18.6 eV.

This element is not observed in the sun.

Leckrone et al. (1991a) detected an absorption line at 1937 in the spectrum of one Ap star of the Hg-Mn subgroup, which they identify with an AsI line from multiplet 1.


As has one stable isotope, As75 and 13 short-lived isotopes and isomers. In the solar system only As75 is observed.


As can be produced by the r process and the s process.

Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.