Why do silicon atoms form single bonds?
Atoms generally bond together so that energy levels are filled. A silicon atom needs to find four other electrons to "borrow" ( ionic bonding ) or to "share" ( covalent bonding ). Those additional four electrons bring the number of valence electrons to the desired eight that will fill silicon's valence shell. In the silicon crystals that form the backbone of the electronics industry, each silicon atom forms covalent bonds with four other silicon atoms, sharing one of its electrons (and receiving a shared electron in return) from each of the four neighbors. Such bonding is best illustrated using a lattice diagram as shown to the right below. The red circles represent the positive core of silicon atoms. The atomic core consists of the nucleus (which contains 14 protons and 14 neutrons in the most common isotope of silicon) and the non-valence electrons (10 of them in silicon). We can let the circles include the non-valence electrons since those elec
