This is indicated from the abnormally low value of the third
ionisation enthalpy of lanthanum, gadolinium and lutetium In their chemical behaviour, in general, the earlier members of the series
are quite reactive similar to calcium but, with increasing atomic number,
they behave more like aluminium Values for E
o for the half-reaction:
Ln
3+(aq) + 3e
– ® Ln(s)
4 5