Chapter 12 The Solid State - 12-2 Structures and Formulas of Ionic Solids - Review & Check for Section 12-2 - Page 449: 2

C

In a lattice there are $8\times 1/8$ C atoms in the vertexes and $6\times 1/2$ in each face, so 4 carbon atoms and 4 silicon atoms in the middle of the cell (from the figure). Mass: $4\times (12.011+28.085)\ g/mol\div 6.022\times 10^{23}\ atoms/mol=2.663\times10^{-22}\ g/cell$ Volume: $(436.0\times 10^{-10}\ cm)^3=8.288\times10^{-23}\ cm^3/cell$ Density: $2.663\times10^{-22}\ g/cell\div 8.288\times10^{-23}\ cm^3/cell=3.21\ g/cm^3$