The hitherto elusive disilavinylidene (H2SiSi) molecule, which is in equilibrium with the mono‐bridged (Si(H)SiH) and di‐bridged (Si(H2)Si) isomers, was initially formed in the gas‐phase reaction of ground‐state atomic silicon (Si) with silane (SiH4) under single‐collision conditions in crossed molecular beam experiments. Combined with state‐of‐the‐art electronic structure and statistical calculations, the reaction was found to involve an initial formation of a van der Waals complex in the entrance channel, a submerged barrier to insertion, intersystem crossing (ISC) from the triplet to the singlet manifold, and hydrogen migrations. These studies provide a rare glimpse of silicon chemistry on the molecular level and shed light on the remarkable non‐adiabatic reaction dynamics of silicon, which are quite distinct from those of isovalent carbon systems, providing important insight that reveals an exotic silicon chemistry to form disilavinylidene. Si/C isoelectronicity: The gas‐phase bimolecular reaction of the ground‐state silicon with silane (SiH4) under single‐collision conditions provides a rare glimpse at previously disregarded silicon chemistry on the molecular level, which further develops our understanding of the concept of isoelectronicity proposed about a century ago.