(a) Define atomic radius.
(b) What are the difficulties in determining atomic radius?

Explanation

(a) Atomic radius is the distance between the centre of its nucleus and the outermost shell containing the electron.
(b) Difficulties in determining atomic radius
(i) The size of an atom is very small (`-1.2oversetoA` ie `1.2xx 10^(-10)`)
(ii) The atom is not a rigid sphere, it is more like a spherical cotton ball rather than like a cricket ball.
(iii) It is not possible to isolate an atom and measure its radius.
(iv) The size of an atom depends upon the type of atoms in its neighborhood and also the nature of bonding between them.