From left, an orange H, then 1 black dot above 1 orange dot, then a black O with 2 black dots both above and below, then 1 black dot above 1 orange dot, then an orange H. Refer to the diagram to complete the sentence with the correct numbers. When hydrogen shares electrons with oxygen, the outermost shell of the hydrogen atoms are full with electrons and oxygen’s valence shell is full with electrons. Because the valence shells of these atoms are full, the atoms are stable.