→ The actinoid metals are all silvery in appearance but display a variety of structures. The structural variability is obtained due to irregularities in metallic radii which are far greater than in lanthanoids.
→ The magnetic properties of the actinoids are more complex than those of the lanthanoids.
→ It is evident from the behaviour of the actinoids that the ionization enthalpies of the early actinoids, though not accurately known, but are lower than for the early lanthanoids.
→ The stable oxidation state of all the lanthanoids is (+3). In actinoids, oxidation states (+2) to (+6) are seen.
→ In lanthanoids only promethium is radioactive but all the actinoids are radioactive.