Thus, the configurations of Am and Cm are [Rn] 5f 
77s
2 and
[Rn] 5f
 76d
17s
2 Although the 5f orbitals resemble the 4f orbitals in their
angular part of the wave-function, they are not as buried as 4f orbitals
and hence 5f electrons can participate in bonding to a far greater extent The general trend in lanthanoids is observable in the actinoids as well There is a gradual decrease in the size of atoms or M
3+ ions across the
series