Chemical shifts of the K (alpha 1) and K (alpha 2) lines (the 2p (3/2) -> 1s (1/2) and 2p (1/2) -> 1s (1/2) transitions, respectively) of the X-ray emission spectrum of the Yb atom in fluorides have been calculated by ab initio modeling the electronic structure. The valence transition Yb(II) -> Yb(III) has been analyzed by examples of YbF2, YbF3, and Yb2F4 molecules and YbF2 (+) cation. The relativistic pseudopotential and basis sets corresponding to it have been constructed for the ytterbium atom. They were used in calculations by the two-component noncollinear version of the density functional theory (DFT) with the PBE0 exchange-correlation functional. Results for the three-coordinated Yb(II) in the FYbF2YbF dimer demonstrated a very weak dependence of the chemical shift on the coordination number of the Yb atom and on the molecular association of ytterbium difluoride. Chemical shifts of the X-ray emission spectrum for the ytterbium compound are related mainly to the change in the occupation of the 4 f shell.