By comparing the site-specific adsorption of N2O with the non-site-specific adsorption of O2 at the clean Si(110) surface which shows a prominent 5 × 1 superstructure (both at 300 K), employing Auger electron spectroscopy (AES) and low energy electron diffraction (LEED), a model of the atomic nature of this surface has been derived which is in agreement with previous LEED and recent scanning tunneling microscopy (STM) work. The description of the real ‘5 × 1’ reconstructed Si(110) surface is based on a reduction of dangling bonds which is due to the formation of adatoms. The model also includes a kind of rest atoms, and atoms in nearest neighbour top layer chains along  (A). It is the ratio adatoms/rest-atoms/A-atoms which determines the primary superstructure. The spatial variation of this ratio at the same Si(110) surface is examined, which cannot be excluded as evidenced by STM, and is found to itself account for the more or less visible streaks (or even spots) very often reported in LEED studies.