An element crystallizes in a face-centered cubic lattice. If the length of an edge of the unit cell is 0.408 nm, and the density of the element is 19.3 g/cm3 , what is the identity of the element?

Au

Explanation:

For the density of a face-centered cubic:

where

= molar mass of the compound

avogadro's constant

the volume of a unit cell

Given that:

Density = 19.30 g/cm³

a = 0.408 nm

a =

a =

∴

Thus, the molar mass of 197.37 g/mol element is Gold (Au).

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally