What region of the electromagnetic spectrum contains wavelengths the size of an atom? (10^-10 meters) what frequency does this wavelength correspond to?

If a photon has a wavelength of about 10^-10 meters, it would be certainly in the X rays region and it would have a frequency of 2.99792458x10^18 Hz, that you can easily calculate using the relation that states that the product of the wavelength and the frequency of an electromagnetic wave aka light is always equal to 299,792,458 m/s which is the exact value of the speed of light!

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.