We investigate the electrical properties of individual silicon nanocrystals (NCs) by means of atomic/electrostatic force microscopy at atmospheric pressure, with the sensitivity of the elementary charge. Using a tip bias close to the sample surface potential for the sample topography imaging, NCs reveal charge blinking properties, corresponding to multi-state charge fluctuations of their defect states. A transition from the NC charge state blinking to NC charging is observed upon biasing the atomic force microscopy tip during topography imaging, leading to both charging of the sample oxide surface and of the NCs, together with faint diffusion of the NC charge along the sample oxide surface. Our results achieved with standard atomic force microscopy demonstrate the possibility to produce experimental results on the electrostatic properties of silicon nanocrystals in the elementary charge sensitivity limit, which is of primary importance for charge-sensitive electro-optical devices.