Question

By Xray studies, the packing of atoms in a crystal of gold is found to be in layers such that starting from any layer, every fourth layer is found to be idential, Then density of gold is found to be 19.4 g cm-3 and its atomic mass is 197amu. a) The coordination no of gold atom in the crystal is b)The fraction occupied by gold atoms in the crystal is>​

Answer 1

Explanation:

By X-ray studies, the packing of atoms in a crystal of gold is found to be in layers such that starting from any layer, every fourth layer is found to be exactly identical . The density of gold is found to be 19.4 g cm^(-3) and its atomic mass is 197 a.m.u. <br> The coordination number of gold atom in the crystal is.

Answer 2

Answer:

The third layer's spheres are not lined up with those of the first or second layer in cubic tight packing. Therefore, the exact pattern of layers may be expressed as ABCABC if we take the first layer to be "A," the second layer to be "B," and the third layer to be "C." Cubic close-packed (CCP) or face-centered cubic (FCC) structures are the names given to this type of crystal.

Explanation:

Layers are arranged in a cubic tight packing pattern of the ABC ABC..... kind.

Consequently, 12 is the coordination number.

The crystal of gold possesses cubic close packing i.e., CCP.

The packing percentage in CCP is 74%.

So, the packing fraction = 74% = $\frac{74}{100}$ = 0.74

Hence, a) the coordination number of gold atoms in the crystal is 12. b)The fraction occupied by gold atoms in the crystal is 0.74.

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