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Q

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Crystals
« on: July 05, 2021, 01:03:49 PM »
Experimentally it has been found that nickel has a density of 8,9 gcm-3 and that radius of its atom is 1,25 Å. Determine which type of cubic crystal lattice does nickel crystalize in.
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I don't know how to approach the problem because I cannot get a hang of how to calculate side of the unit cell. I know that it cannot possibly be cP (primitive) for the reason that the only metal that crystalizes in that crystal lattice is α-polonium. for that sake, it remains only cI or cF, but in both of these the relationship between radius and length of the side is differently expressed; cF: a=2√(2)r, cI: a=(4√(3)r)/(3)

sjb

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Re: Crystals
« Reply #1 on: July 05, 2021, 03:26:22 PM »

Orcio_87

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Re: Crystals
« Reply #2 on: July 05, 2021, 04:01:46 PM »
How to calculate side of the unit cell ?

For cF (r - is the atom radius):

a = 2r √2

As of cI I think it will be:

a = 4r / √3

Q

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Re: Crystals
« Reply #3 on: July 06, 2021, 04:54:06 AM »
How to calculate side of the unit cell ?

For cF (r - is the atom radius):

a = 2r √2

As of cI I think it will be:

a = 4r / √3

I understand that, but I have to figure out which of these two unit cells does nickel crystalize in.

Orcio_87

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Re: Crystals
« Reply #4 on: July 06, 2021, 05:07:14 AM »
Figuring out may be a bad way.

Did you considered calculating density of cI and cF unit cells and comparing it to the experimental data ?