anyone can help about atomic radii of lanthanides & actinides.?

Answer 1

I think you're talking about the lanthanide contraction.

Start at the link below. Do a google search if you want more.

Answer 2

nothing in general can be said about the radii of lanthnoids and actinoids however they generally decreases along the group known as lanthnoid contraction thus making the radii nearly same.

Answer 3

uh what about it? it's larger than some, and since most are radioactive the structure is unstable and you can see that in the unfilled shells. other than that pick up a chemistry text and start reading