Why is the C 60form of carbon called buckminsterfullerene?

Which of the following elements reacts with sulfur to form a solid in which the sulfur atoms form a closest packed array with all of the octahedral holes occupied: Li, Na, Be, Ca, or Al?

The solid-state structure of silicon is shown below. Unit cell for silicon (a) Describe this crystal as pc, bcc, or fcc. (b) What type of holes are occupied in the lattice? (c) How many Si atoms are there per unit cell? (d) Calculate the density of silicon in g/cm3 (given that the cube edge has a length of 543.1 pm). (e) Estimate the radius of the silicon atom. (Note: The Si atoms on the edges do not touch one another.)

Materials containing the elements Y, Ba, Cu, and O that are superconductors (electrical resistance equals zero) at temperatures above that of liquid nitrogen were recently discovered. The structures of these materials are based on the perovskite structure. Were they to have the ideal perovskite structure, the superconductor would have the structure shown in pant (a) of the following figure. a. What is the formula of this ideal perovskite material? b. How is this structure related to the perovskite structure shown in Exercise 85? These materials, however, do not act as superconductors unless they are deficient in oxygen. The structure of the actual superconducting phase appears to be that shown in pan (b) of the figure. c. What is the formula of this material?

If one edge of the silicon carbide unit cell is 436.0 pm, what is the calculated density of this compound? (a) 0.803 g/cm3 (b) 0311g/cm3 (c) 321 g/cm3

If an ionic solid has an fcc lattice of anions (X) and all of the tetrahedral holes are occupied by metal cations (M), is the formula of the compound MX, MX2, or M2X?

Like ZnS, lead(II) sulfide, PbS (commonly called galena), has a 1:1 empirical formula with a 2+ cation combined with the sulfide anion. Unit cell of PbS Sample of galena Does PbS have the same solid structure as ZnS? If different, how are they different? How is the unit cell of PbS related to its formula?

Phase diagrams for materials that have allotropes can be more complicated than those shown in the chapter. Use the phase diagram for carbon given here to answer the following questions. (a) How many triple points are present and what phases are in equilibrium for each? (b) Is there a single point where all four phases are in equilibrium? (c) Which is more stable at high pressures, diamond or graphite? (d) Which is the stable phase of carbon at room temperature and 1 atmosphere pressure?

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?