Homework SourseAr is a solid below 189 oC with a facecentered cubic array o
Ar is a solid below -189 oC with a face-centered cubic array of atoms and a supposed density of 1.66 g/cm3. Assuming that the atoms are spheres in contact along the face diagonal, what is the radius of a Ar atom (in Angstroms)? An angstrom = 10-10 m or 10-8 cm. Hint, first find the length of an edge of the unit cell. (Argon\'s actual density is 1.65 g/cm3.)
Ar is a solid below -189 oC with a face-centered cubic array of atoms and a supposed density of 1.66 g/cm3. Assuming that the atoms are spheres in contact along the face diagonal, what is the radius of a Ar atom (in Angstroms)? An angstrom = 10-10 m or 10-8 cm. Hint, first find the length of an edge of the unit cell. (Argon\'s actual density is 1.65 g/cm3.)
Solution
density=mass/volume
number of atoms in 1 unit cell=4
or density=molar mass*n/(a^3*Na)
or 1650=40*10^-3*4/(a^3*6*10^23)
or a=5.447*10^-10 m
so 4r=2^0.5 *a
so,
4*r=2^0.5 * 5.447*10^-10
or r=1.926*10^-10 m
=1.926 Angstormss
