The oxygen atom has six valence electrons in its ground state.
In the ground state, an oxygen atom has an electron configuration of 1s² 2s² 2p⁴. The valence electrons are those electrons present in the outermost energy level, which for oxygen are in the 2p sublevel. In this case, there are four electrons in the 2p sublevel, and since each orbital can hold a maximum of two electrons, there are six valence electrons in total.