It is worth noting that for upper-level chemistry courses where epoxides would be introduced, the epoxide ring arrangement is one of the possible arrangements in addition to the straight-chain Lewis structures described above. As the calculated total bond number is 7 and four hydrogen atoms can form four single bonds, the only possible ring arrangement of C2H4O is ethylene oxide which forms three single bonds between C, C, and O. The formal charges on all atoms in the structure equal to zero, this is a stable compound. The number of bonding electrons = (3) -( ) -1 = 16e --11e --1e -= 4e - (5). Bond number = 4e -/2 = 2 bonds (double bond) (6). Only one bonding spot (K = 2 -1 = 1), meaning only one possible combination, skip this step (7)a. Complete octet on one atom, leaving the other atom filled with the rest electrons for all possible structures. 8). Check for the formal charges on each atom, and the structure with zeros on both atoms is the best representative for NO.