I second **Squink **that what you mean by the ratio of expansion needs to be clarified a little. But if you just wonder what relative packing densities of aluminum vs. copper ions is, that’s easy: copper has about 9x10[sup]22[/sup] atoms per cc at solid density, while aluminum has only 6x10[sup]22[/sup]. If copper expanded to a gas at atmospheric densities and temperatures, where the atom density is a few times 10[sup]18[/sup], and expanded by a factor of 67K, then aluminum expanded to the same density would increase in volume by a factor of only 44K. Still impressive.
Sorry, but this doesn’t really make any sense. Elemental copper has a melting point of 1358 Kelvin, and vaporization point of 2835 Kelvin. Once it is a gas, it’ll act like…well, a gas, such that the volume will be related to some function of pressure and temperature. I’ve never heard of anyone working with gaseous copper in any quantity, so I don’t know how much it would vary from and ideal gas, but it won’t have any kind of constant volume. Ditto for aluminum. What kind of class did you say this was?