Unit Cell Video Lessons

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# Problem: Iridium crystallizes in a face-centered cubic unit cell that has an edge length of 3.833 Å. The atom in the center of the face is in contact with the corner atoms, as shown in the drawing.Calculate the density of iridium metal.

###### FREE Expert Solution

We are being asked for the density of Iridium Ir, given the unit cell edge length of 3.833 Å.

Looking at the illustration, Iridium has a face-centered cubic structure.

Recall that the face-centered cubic lattice contains an atom in each of the faces of the cube and an atom in each of the corners

It looks like this:

There are 4 atoms in a unit cell for a Face Centered Cubic structure (z=4).

An FCC unit cell contains four atomsone-eighth of an atom at each of the eight corners (8 x 1/8 = 1 atom from the corners) and one-half of an atom on each of the six faces (6 x 1/2 = 3 atoms from the faces).

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###### Problem Details

Iridium crystallizes in a face-centered cubic unit cell that has an edge length of 3.833 Å. The atom in the center of the face is in contact with the corner atoms, as shown in the drawing.

Calculate the density of iridium metal.