AbstractRelativistic effects are known to alter the chemical bonds and spectroscopic properties of heavy‐element compounds. In this work, we introduce the concept of spin–orbit (SO) electronegativity of a heavy atom, as reflected by an SO‐induced change in the interatomic distance between the heavy atom (HA) and a neighboring light atom (LA). We provide a transparent interpretation of these SO effects by using the concept of spin–orbit electron deformation density (SO‐EDD). Spin–orbit coupling at the HA induces rearrangement of the electron density for the scalar‐relativistically optimized geometry that, in turn, exerts a new force on the LA. The resulting expansion or contraction of the HA−LA bond depends on the nature and electron configuration of the HA. In addition, we quantify the change in atomic electronegativity induced by SO coupling for a series of hydrides, thereby complementing the SO‐EDD picture. The trends in the SO‐induced electronegativity and the HA−LA bond length across the periodic table of elements are demonstrated and interpreted, and also linked, intuitively, with the SO‐induced NMR shielding at the LA.