* Bragg's Law: Diffraction of X-rays or other electromagnetic radiation by a crystal lattice is governed by Bragg's Law:
nλ = 2d sin θ
Where:
* n is an integer (order of diffraction)
* λ is the wavelength of the radiation
* d is the spacing between crystal planes (lattice spacing)
* θ is the angle of incidence of the radiation
* Sodium Yellow Light Wavelength: Sodium yellow light has a wavelength of about 589 nm (nanometers). This wavelength is much larger than the typical spacing between atomic planes in crystals (which is on the order of a few angstroms, or 0.1 nm).
* Diffraction Limit: For effective diffraction, the wavelength of the radiation should be comparable to or smaller than the spacing between the diffracting elements (the lattice planes). Since the wavelength of sodium yellow light is much larger, it won't be diffracted by the NaCl crystal lattice.
What to use instead:
To determine the lattice spacing of NaCl, you need to use radiation with a wavelength comparable to the interatomic distances in the crystal. X-rays are commonly used for this purpose because they have wavelengths in the angstrom range (0.1-10 nm).
In summary:
* Sodium yellow light has a wavelength too large for diffraction by NaCl crystal lattice.
* X-rays are the appropriate tool for determining lattice spacing due to their shorter wavelengths.
