In addition to the types of compounds discussed so far, the group IVA elements also form several other
interesting compounds. Silicon has enough nonmetallic character that it reacts with many metals to
form binary silicides . Some of these compounds can be considered as alloys of silicon and the metal
that result in formulas such as Mo 3 Si and TiSi 2 . The presence of Si 2 2 ions is indicated by a Si – Si distance
that is virtually identical to that found in the element, which has the diamond structure. Calcium
carbide contains the C 2 2 , so it is an acetylide that is analogous to the silicon compounds.