The structural variability is obtained
due to irregularities in metallic radii which are far greater
than in lanthanoids 4 6 4 General
Characteristics
and Comparison
with Lanthanoids
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
5
5
5
5
5
6
6
6
6
7
7
Table 4