Question

why is the atomic size of neon greater than fluorine

Answer 1

Fluorine is highly electronegative. The attraction between nucleus and the outermost electrons are large . Therefore , the atomic radius decreases. But in case of neon, the electronegativity is less. Hence the attraction is less. Neon has weak van der waals forces. So neon is large in size than fluorine.

Answer 2

In neon the electrons are more crowded and hence the force of attraction from the nucleus decreases and this results in greater size of neon than fluorine.