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A crystal mth a simple cubic lattice and a monoatomic basis has an atomic ra- dius of 2.5 A and an atomic weight of 5.42. Calculate its density, assuming that the atoms touch each other.

Respuesta :

Answer:

density = 0.071984 g/cm³

Explanation:

For a simple cubic lattice structure;

There are 8 atoms in the unit cell, with each edge of the cell contributing 1/8th atom to one unit cell.

Thus, in a unit cell, the required number of atoms = 8/8 = 1

The mass of the unit cell can be calculated by using the formula:

[tex]Mass \ of \ the \ unit \ cell = \dfrac{no \ of atoms \ \times Atomic \ weight }{Avogadro \ No}[/tex]

[tex]Mass \ of \ the \ unit \ cell = \dfrac{1 \ \times 5.42 }{6.023\times 10^{23}}[/tex]

[tex]Mass \ of \ the \ unit \ cell = 8.998 \times 10^{24 } \ g[/tex]

Similarly, given the atomic radius = 2.5 angstrom = [tex]2.5 \times 10^{-10} \ meter[/tex]

Thus, volume V = a³

The edge length for the simple cubic radius  is:

a = 2 × r

a = 2 × [tex]2.5 \times 10^{-10}[/tex]

a = [tex]5 \times 10^{-10}[/tex] m

a = [tex]5 \times 10^{-8} \ cm[/tex]

Now;

volume V = a³

volume V = [tex](5 \times 10^8)^3[/tex]

volume V = [tex]1.25 \times 10^{-22}[/tex] cm³

Finally; the density = mass/volume

density =  [tex]\dfrac{8.998 \times 10^{-24}}{1.25 \times 10^{-22}}[/tex]

density = 0.071984 g/cm³