The 5f electrons, will therefore,
be more effectively shielded from the nuclear charge than the 4f electrons
of the corresponding lanthanoids Because the outer electrons are less
firmly held, they are available for bonding in the actinoids A comparison of the actinoids with the lanthanoids, with respect to
different characteristics as discussed above, reveals that behaviour similar
to that of the lanthanoids is not evident until the second half of the
actinoid series However, even the early actinoids resemble the lanthanoids
in showing close similarities with each other and in gradual variation in
properties which do not entail change in oxidation state