The melting temperature of the fluorides of selected alkali metals and alkaline earths are listed below (see Table). If one considers the trend of the listed melting temperatures in terms of both the ionic character of the bonds and the ionic potentials of the compounds, which of these compounds follow Goldschmidt’s rules and which one do not, and why?
Fluoride compounds Ionic Potential Melting temperature (0C)
LiF 1.31 845
NaF 1.96 993
KF 0.72 858
RbF 0.657 795
CsF 0.598 682
BeF2 4.44 800 (sublimes)
MgF2 2.77 1261
CaF2 2 1423
SrF2 1.69 1573
BaF2 1.48 1355
3 answers