Concept explainers
In an FCC structure, the atoms are found on the corners of the cubic unit cell and at the center of each face. The unit cell has an edge whose length is the distance from the center of one corner atom to the center of another corner atom on the same edge. The atoms on the diagonal of any face are touching. One of the faces of the unit cell is shown below in the following:
a. Show the distance
b. What is the relationship between the length of the face diagonal and the radius of the atoms in the cell?
Face diagonal
c. How is the radius of the atoms related to
d. Silver metal crystals have an FCC structure. The unit cell edge in silver is
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Chapter 16 Solutions
EBK CHEMICAL PRINCIPLES IN THE LABORATO
- Consider the three types of cubic units cells. (a) Assuming that the spherical atoms or ions in a primitive cubic unit cell just touch along the cubes edges, calculate the percentage of occupied space within the unit cell. (Recall that the volume of a sphere is (4/3)r3, where r is the radius of the sphere.) (b) Compare the percentage of occupied space in the primitive cell (pc) with the bcc and fcc unit cells. Based on this, will a metal in these three forms have the same or different densities? If different, in which is it most dense? In which is it least dense?arrow_forwardThe edge length of the unit cell of tantalum metal, Ta, is 330.6 pm; the unit cell is body-centered cubic (one atom at each lattice point). Tantalum has a density of 16.69 g/cm3. What is the mass of a tantalum atom? Use Avogadros number to calculate the atomic mass of tantalum.arrow_forwardCalculate the percent of volume that is actually occupied by spheres in a body-centered cubic lattice of identical spheres You can do this by first relating the radius of a sphere, r, to the length of an edge of a unit cell, l. (Note that the spheres do not touch along an edge but do touch along a diagonal passing through the body-centered sphere.) Then calculate the volume of a unit cell in terms of r. The volume occupied by spheres equals the number of spheres per unit cell times the volume of a sphere (4r3/3).arrow_forward
- Crystalline polonium has a primitive cubic unit cell, lithium has a body-centered cubic unit cell, and calcium has a face-centered cubic unit cell. How many Po atoms belong to one unit cell? How many Li atoms belong to one unit cell? How many Ca atoms belong to one unit cell? Draw each unit cell. Indicate on your drawing what fraction of each atom lies within the unit cell.arrow_forwardAluminum metal crystallizes with a face-centered cubic unit cell. The volume of the cell is 0.0662 nm3. (a) What is the atomic radius of aluminum in cm? (b) What is the volume of a single aluminum atom? (c) What is the density of a single aluminum atom? (d) In face-centered cubic cell packing, the fraction of empty space is 26.0%. When this is factored in, what is the calculated density of aluminum?arrow_forwardThe unit cell of silicon carbide, SiC, is illustrated below. (a) In what type of unit cell are the (dark gray) C atoms arranged? (b) If one edge of the silicon carbide unit cell is 436.0 pm, what is the calculated density of this compound? A portion of the solid-state structure of silicon carbide.arrow_forward
- Spinel is a mineral that contains 37.9% aluminum, 17.1% magnesium, and 45.0% oxygen, by mass, and has a density of 3.57 g/cm3.The edge of the cubic unit cell measures 809 pm. How many of each type of ion are present in the unit cell?arrow_forwardCalculate the percent of volume that is actually occupied by spheres in a face-centered cubic lattice of identical spheres. You can do this by first relating the radius of a sphere, r, to the length of an edge of a unit cell, l. (Note that the spheres do not touch along an edge but do touch along the diagonal of a face.) Then calculate the volume of a unit cell in terms of r. The volume occupied by spheres equals the number of spheres per unit cell times the volume of a sphere (4r3/3).arrow_forwardWhat is a lattice? What is a unit cell? Describe a simple cubic unit cell. How many net atoms are contained in a simple cubic unit cell? How is the radius of the atom related to the cube edge length for a simple cubic unit cell? Answer the same questions for the body-centered cubic unit cell and for the face-centered unit cell.arrow_forward
- Lithium hydride (LiH) has the sodium chloride structure, and the length of the edge of the unit cell is 4.086 108 cm. Calculate the density of this solid.arrow_forwardOutline a two-dimensional unit cell for the pattern shown here. If the black squares are labeled A and the white squares are B, what is the simplest formula for a compound based on this pattern?arrow_forwardIridium metal, Ir, crystallizes in a face-centered cubic (close-packed) structure. The edge length of the unit cell was found by x-ray diffraction to be 383.9 pm. The density of iridium is 22.42 g/cm3. Calculate the mass of an iridium atom. Use Avogadros number to calculate the atomic mass of iridium.arrow_forward
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