This may be referred to as the actinoid contraction (like lanthanoid
contraction) The contraction is, however, greater from element to element
in this series resulting from poor shielding by 5f electrons There is a greater range of oxidation states, which is in part attributed to
the fact that the 5f, 6d and 7s levels are of comparable energies The
known oxidation states of actinoids are listed in Table 4