What is the oxidation number of Cr in CrSe?
The known oxidation numbers of chromium are +2, +3, and +6, while the known oxidation numbers of selenium are -2, +4, and +6. Within this constraint, the only oxidation numbers that can match the formula given are -2 for selenium and +2 for chromium.
True however I believe the question did not place Chromium in any compund therefore technically its oxidation number would be O as it is in its natural state as Cr. Chromium (symbol: Cr) can have several oxidation numbers, depending on the nature of the compound it is found in. Possible oxidation numbers for Chromium are: 6 5 4 3 2 1 -1 -2
K2CrO4 has 2x K(potassium) atoms per 1xCr (chromium) atom per 4xO (oxygen) atoms. The oxidation number of oxygen is always -2 (except when chemically bound to fluorine, which is the only element higher in electronegativity/ionization energy than oxygen) K is an alkali metal, (in column 1A of the periodic table) and henceforth will almost always have an oxidation number of +1. With this information, we can deduct that... 2 K atoms will each have +1…