Question

the atomic radius refers to the distance from the nucleus of an atom to A. It's proton cloud B. It's electron cloud C. It's neutron cluster D. The nucleus of another atom

Answer 1

B. Its electron cloud (the boundary of it). This is the outside of the atom. Just as we measure a circle's radius from the centre to the circumference, we measure an atom's radius from its nucleus to its cloud of electrons.

Answer 2

B. It's electron cloud

Step-by-step explanation:

According to the quantum mechanical model of the atom, electrons no longer behave as particles but as waves. According to Heisenberg there is always a probability of finding electrons in space as they exist as electron clouds but it is not possible to define with certainty the position of an electron. Therefore an atom consists of the central nucleus and the electron cloud.