Calculate the radius of a platinum atom in cm, given that Pt has an FCC crystal structure, a density of 21.4 g/cm3, and an atomic weight of 195.08 g/mol.

Respuesta :

Answer:

Radius of platinum atom is [tex]1,38\times10^{-8} \ cm.[/tex]

Explanation:

We know, Density in solid state is also given by , [tex]\rho=\dfrac{Z\times M}{N_A\times a^3}[/tex]

Here, Z= total no of atom or molecule per unit cell. ( Z = 4 for FCC structure )

M = atomic weight = 195.08 gm/mol.

N_A= Avogadro's number = [tex]6.023\times 10^{23} .[/tex]

a= size of side of cube.

Also for, FCC crystal [tex]a=\sqrt2\times 2r[/tex]    ....1

Since,[tex]\rho=\dfrac{Z\times M}{N_A\times a^3}\\[/tex]

Therefore, [tex]a^3=\dfrac{Z\times M}{N_A\times \rho}[/tex]

Putting all values , [tex]a=3.9\times 10^{-8} \ cm.[/tex]

Putting value of a in equation 1 we get,

[tex]r=\dfrac{a}{\sqrt2\times2}=1.38\times 10^{-8} \ cm.[/tex]

Hence, this is the required solution.