Final answer:
A hydrogen atom is approximately 1.2 x 10^-10 meters in diameter, which is 100,000 times larger than the diameter of a proton.
Step-by-step explanation:
The size of a proton is on the order of 10-15 meters, as can be inferred from the value of 1.2 femtometers given for the proton radius (1 fm = 10-15 m).
As given, the diameter of a hydrogen atom is 100,000 times the diameter of a proton.
To find the size of a hydrogen atom, we multiply the diameter of a proton by 100,000.
Therefore, the size of a hydrogen atom is 1.2 x 10-15 m (the diameter of the proton) multiplied by 100,000, which is 1.2 x 10-10 m.
This is already in scientific notation.
Comparing to the provided electric potential example where the radius of a hydrogen atom is about 0.5 x 10-10 m, we can confirm the order of magnitude for the hydrogen atom's diameter.