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 The lanthanoid
and actinoid contractions, have extended effects on the sizes, and
therefore, the properties of the elements succeeding them in their
respective periods The lanthanoid contraction is more important because
the chemistry of elements succeeding the actinoids are much less known
at the present time 4