16th Group

    Oxygen (O)

    • Default: H2O

    • Molecules:

      • Neutral atom:

        • Implicit Hydrogens are added to have 2 bonds (if Oxygen has at least 1 bond).

        • More than 2 bonds are forbidden

      • Charged atom:

        • Positive charge:

          • 1+: 3 bonds are necessary (including implicit Hydrogens).

          • 2+: 4 bonds are necessary (including implicit Hydrogens).

          • 3+: 3 bonds are necessary (including implicit Hydrogens).

          • 4+: 2 bonds are necessary (including implicit Hydrogens).

          • 5+: 1 bonds are necessary (including implicit Hydrogens).

          • 6+: 0 bonds are necessary (including implicit Hydrogens).

        • Negative charge: One or two the negative charges are accepted, with one or zero ligands, respectively.

      • Radical: Every added radical on these atoms decreases by one the number of bonds. Maximum two added radical is allowed.

      • Aromatic compounds: Oxygen may form aromatic bonds as well.

    Sulfur (S), Selenium (Se), Tellurium (Te), Polonium (Po)

    • Default: H2S, H2Se, H2Te, H2Po

    • Molecules:

      • Neutral atom:

        • 1 bond: 1 implicit Hydrogen is added

        • 2 bond: 0 implicit Hydrogen is added

        • 3 bond: valence error on S/Se/Te/Po atom

        • 4 bond: 0 implicit Hydrogen is added

        • 5 bond: 1 implicit Hydrogen is added

        • 6 bond: 0 implicit Hydrogen is added

        • More than 6 bonds are forbidden

      • Charged atom:

        • Positive charge:

          • Sulfur (S):

            • 1+: 3 or 5 bonds are necessary (including implicit Hydrogens).

            • 2+: 4 bonds are necessary (including implicit Hydrogens).

            • 3+: 3 bonds are necessary (including implicit Hydrogens).

            • 4+: 2 bonds are necessary (including implicit Hydrogens).

            • 5+: 1 bond is necessary (including implicit Hydrogens).

            • 6+: 0 bond is allowed.

            • 7+ or more: not allowed.

          • Selenium (Se), Tellurium (Te), Polonium (Po):

            • 1+: 1, 3 or 5 bonds are necessary (including implicit Hydrogens).

            • 2+: 0 or 4 bonds are necessary (including implicit Hydrogens).

            • 3+: 1 or 3 bonds are necessary (including implicit Hydrogens).

            • 4+: 0 or 2 bonds are necessary (including implicit Hydrogens).

            • 5+: 1 bond is necessary (including implicit Hydrogens).

            • 6+: 0 bond is allowed.

            • 7+ or more: not allowed.

        • Negative charge:

          • 1-: 1 bond accepted. ( Exception: 2 double bonded oxygens and 1 more ligand connected by a single bond)

          • 2-: Zero ligand is accepted

      • Radical: Every added radical on these atoms decreases by one the number of bonds. Maximum 2 added radical is allowed.

      • Aromatic compounds: Sulfur may form aromatic bonds as well.