Inorganic elements

Group VIA

Atomic Number
Electron configuration
Oxidation numbers
 Atomic Weight
Chromium (Cr) 24 [Ar] 3d54S +2, +3, +6 52.00
Molybdenum (Mo) 42 [Kr] 4d55S +3, +4, +6 95.94
Tungsten (W) 74 [Xe] 4f145d46s2 +3, +4, +6 183.85

Chromium (group VIA)
Atomic Number
Electron configuration
Oxidation numbers
 Atomic Weight
Chromium (Cr) 24 [Ar] 3d54S +2, +3, +6 52.00

The most stable oxidation state of chromium is +3.

Oxygenated compounds of chromium

Name, example OxNum Properties
CrO   + 2 basic
Cr(OH)2   + 2 basic
Cr2O3   +3 amphoteric
CrO2- Chromite, Potassium chromite: KCrO2 +3  
CrO42- Chromate, Potassium chromate: K2CrO4 + 6  
Cr2O72- Dichromate, Potassium dichromate: K2Cr2O7. + 6  
       

Note: The name dichromate arise from the fact that it is thought as the dimerization of chromate.

Preparation of chromium

The principal chromium ore is the mixed oxide known as chromite (FeO.Cr2O3 also written as FeCr2O4)

 

Molybdenum (group VIA)
Atomic Number
Electron configuration
Oxidation numbers
 Atomic Weight
Molybdenum (Mo) 42 [Kr] 4d55S +3, +4 +6 95.94

Tungsten (group VIA)
Atomic Number
Electron configuration
Oxidation numbers
 Atomic Weight
Tungsten (W) 74 [Xe] 4f145d46s2 -2, -1, 0, 183.85