To make a large-scale representation of a hydrogen atom in its ground state, you start with a super ball (D=3.74 cm) to represent the nucleus. How far away, R, in km will you have to put the representation electron?

Answer 1

The diameter of a hydrogen atom is 1.06*10^-10m

Scale that diameter up to 3.74cm:

3.74*10^-2/1.06*10^-10 = 3.53*10^8m

so, the radius would be 1.76*10^5km, or about 43% of the way to the moon.