Germanium, crystal structure melting point

Silicon and germanium crystallize in the diamond structure. However, they have somewhat weaker covalent bonds than carbon as a consequence of less efficient orbital overlap. These weaker bonds result in lower melting points for silicon (1420°C for Si and 945°C for Ge, compared with 4100°C for diamond) and greater chemical reactivity. Both sihcon and germanium are semiconductors, described in Chapter 7. 

The densities of liquids under normal pressures are not too dissimilar to those of their solids between the melting and boiling points. Generally a liquid is less dense than its solid at the melting point, but there are a few exceptions of which water is one ice floats on water. These less dense solids have rather open crystal structures. Silicon, germanium and tin are other examples. Another similarity between normal liquids and solids is that they have a low compressibility due to there not being a great deal of space between the molecules in a liquid. 

---