Finding the size of an atom is a lot more complicated than measuring the radius of a ball because ltbrlt (i) the size of an atom is very small
(ii) the electron cloub sorrounding the nucleus does not have a sharp boundary.
(iii) we cannot isolate a single and measure its diameter the way we can measure the diameter of a ball
(iv) atomic radius charges as atom moves from one environment to the other and also when the atom is present in different bonded states.

Options

A. `(i),(ii)`
B. `(ii),(iii)`
C. `(i),(ii),(iii),(iv)`
D. `(ii),(iii),(iv)`

Answer

C

Explanation

`(a)` Atomic radii are so small that they are often stated in Angustoms `(1Å = 10^(-10)m)` or in the `SI` units, nanometers `(1nm = 10^(-9)m)` or picometers `(1"pm" = 10^(-12)m)`. To convert form `Å` to `nm`, move the decimal point one place to the left `(1Å =0.1 nm`). for example, the atomic radius of `Li` is `1.52Å` or `0.512 nm`.
`(2)` Atomic orbitals described in terms of probability desctributions of electrons over certain region in space are somewhat indefinite because the probability of finding an electron never becomes zero even at great distance form the nucleus, i.e., the size of an atom cannot be defined and determined precisely.
`(4)` If we are measuring the size of an atom when it is occupying a lattice site in the crystal, the value will be different from the one when it is colliding with another atom in the gaseous state. Furthermore, the size of the neutral atom will be different from the one when it is present as a cation or anion. Consequently, we cannot have one set of atomic radii applicable under all conditions.