21 The elements of chromium and Manganese family 21.1 The elemental substances of Cr,Mo and W 21.2 The compounds of chromium 21.3 The elemental substance of Mn -21.4 The compounds of manganese21.2 The compounds of chromium 21.1 The elemental substances of Cr, Mo and W §21 The elements of chromium and Manganese family 21.3 The elemental substance of Mn 21.4 The compounds of manganese