The oxygen atom has two energy levels, with two electrons in the s orbital of the first, two electrons in the s orbital of the second and four electrons in the p orbital of the second. It has eight electrons, eight protons and eight neutrons.
An oxygen atom has an atomic radius of 0.65 angstroms and an ionic radius of 1.4 angstroms. It atomic volume is 14 cubic centimeters per mole, while its covalent radius is 0.73 angstroms. The atomic number for oxygen is 8 and its atomic weight is 15.99 unified atomic mass units. The possible oxidation states for an atom of oxygen are +2, +1, ?1 and ?2.