This element was discovered in 1803 by W. Wollaston in London. The name alludes to the asteroid Pallas discovered in 1802 by Olbers. Pallas Athene is the name of the goddess of wisdom in Greek mythology.

Ionization energy
PdI 8.3 eV, PdII 19.4 eV, PdIII 32.9 eV.

Absorption lines of PdI
The equivalent width of PdI 3405(2) in the sun is 0.036.

Behavior in non-normal stars
Pd was first discovered by Bidelman (1966) in one Ap star. PdII was found by Adelman (1974) in one Bp star of the Si-4200 subgroup and by Adelman et al. (1979) in another Ap star of the Cr-Eu subgroup.

Pd occurs in the form of six stable isotopes, namely Pd 102 104, 105, 106, 108 and 110, which occur in the solar system with frequencies 1%, 11%, 22%, 27%, 27% and 12% respectively. There exist also 15 short-lived isotopes and isomers. The longest lived is Pdl07 with a half life of 7 × 106 years, which can be used for radioactive dating.

Pd 105, 106 and 108 are produced by both the r process and the s process. Pd110 is a pure r process product, Pd104 a pure s process product and pd102 are pure p process product.

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