For most alkali and alkali-earth elements
the semi-core and
states should be treated as valence states.
For lighter elements (Na-Ca) it is usually sufficient to treat the
the
and
states, respectively, as valence
states ( _pv), whereas for Rb-Sr the
and
states, respectively,
must be treated as valence states ( _sv). Hence the standard potentials are
Na_pv Mg or Mg_pv K_pv or K_sv Ca_pv or Ca_sv Rb_sv Sr_sv Cs_sv Ba_svFor K results should not be sensible to whether K_pv or K_sv is used. Likewise, for Mg the standard potential will be sufficient in most cases.