Final answer:
In the compound K₂Cr₂O₇, the oxidation states are +1 for potassium (K), +6 for chromium (Cr), and -2 for oxygen (O).
Step-by-step explanation:
The student asked about the oxidation state of each element in K₂Cr₂O₇. To calculate the oxidation states, we can use the rules for oxidation numbers and work from known to unknown. We know that potassium (K) has an oxidation state of +1 since it is in group 1 of the periodic table.
Oxygen usually has an oxidation state of -2. The compound is neutral, so all oxidation states must sum up to zero.
Now, let's determine the oxidation state of chromium (Cr). The formula for potassium dichromate is K₂Cr₂O₇. With two potassium ions, we have a total of +2 from potassium. There are seven oxygen atoms, each with an oxidation number of -2, giving us -14 in total.
To balance this, the two chromium atoms together must have an oxidation state that sums up to +12. Therefore, each chromium atom must have an oxidation state of +6.
So, in K₂Cr₂O₇, the oxidation states are: