We report electric field induced phase transitions of Au(111) surfaces and electric field stress induced elongation of Au tips during current voltage measurements with a scanning tunneling microscope (STM) in air. Transitions between the reconstructed square-root 3 x 22 and the unreconstructed 1 x 1 phase of the Au(111) surface are attributed to changes in the electronic surface excess charge density induced by the electric field between the tip and sample. Elongations of STM tips during tunneling spectroscopy give rise to a hysteresis in the current-voltage response at tip-to-sample biases greater than approximately 0.5 V and frequently result in the formation of a mechanical tip-sample contact.