+---------+----------+----------+--------------------+ | Group | VI. | VII. | VIII. | +---------+----------+----------+--------------------+ | Series 1| -- | -- | | | | | | | | " 2| O | F | | | | | | | | " 3| S | Cl | | | | | | | | " 4| Cr | Mn | Fe Co Ni Cu | | | | | | | " 5| Se | Br | | | | | | | | " 6| Mo | -- | Ru Rh Pd Ag | | | | | | | " 7| Te | I | | | | | | | | " 8| -- | -- | -- -- -- -- | | | | | | | " 9| -- | -- | | | | | | | | " 10| W | -- | Os Ir Pt Au | | | | | | | " 11| -- | -- | | | | | | | | " 12| U | -- | | | | | | | +---------+----------+----------+--------------------+ | |R_{2}O_{6}|R_{2}O_{7}| Higher oxides | | | | | | | |RO_{3} | -- | RO_{4} | | | | | | | |RH_{2} | RH | Hydrogen compounds | +---------+----------+----------+--------------------+ TABLE II