Oxidation number rules for Elements and Monoatomic Ions. The oxidation number of any element is zero. The oxidation number of any monoatomic ion is the same as the charge on this ion. Oxidation removal of electrons. Reduction gain of electrons.
MOs can hold two electrons like atomic orbitals but have different shapes.
Lewis structures and the Octet Rule. The Octet Rule works not only for ionic compounds but for molecular compounds too. These numbers are the same. Carbon the most important element of life. Methane the simplest hydrocarbon.