Calculate Highest Freq. & Smallest Wave in Aluminium

[Gasharan]

Homework Statement

Estimate the highest possible frequency (in Hertz), and the smallest possible wavelength, of a sound wave in aluminium, due to the discrete atomic
structure of this material. We're given the mass of aluminum, Young's Modulus, and mass density.

Homework Equations

w=k* √(Y/ρ)

The Attempt at a Solution

Basically, I know that the largest wave has to fit inside the interatomic distance, but I don't know how to find this distance.

 

[BigJDubs]

I also know that the highest frequency is related to Young's Modulus, mass density, and spring constant. However, I'm not sure how to go about finding the highest frequency from this information.