Although Germanium performs amazingly at sites surrounding heterocoordinated impurities and undercoordinated defects or skins with unusual properties having important impact to electronic and optical devices, understanding the behavior of the local bonds and electrons at such sites remain a great challenge. Here we show that a combination of density functional theory calculations, zone-resolved X-ray photoelectron spectrometrics and bond order-length-strength correlation mechanism has enabled us to clarify the physical origin of the Ge 3d core-level shift for the undercoordinated (111) and (100) skin with and without heterocoordinated H2, O2, H2O, H2O2, HF impurities. The Ge 3d level shifts from 27.579 (for an isolated atom) by 1.381 to 28.960 eV upon bulk formation. Atomic undercoordination shifts the binding energy further to 29.823 eV for the (001) and 29.713 eV for the (111) monolayer skin. Addition of O2, HF, H2O, H2O2 and Au impurities results in quantum entrapment by different amounts but H adsorption leads to polarization.