Step 1: Understanding the Question:
Oxidation state is the charge an atom would carry if all bonds were completely ionic.
Oxygen usually has a specific common state, but peroxides are a well-known exception.
Step 2: Key Formula or Approach:
1. Sum of oxidation states in a neutral molecule is zero.
2. Standard oxidation state of Hydrogen is \(+1\).
3. Peroxides contain the \(-O-O-\) linkage.
Step 3: Detailed Explanation:
Take Hydrogen Peroxide (\(H_2O_2\)) as a representative example.
Let the oxidation state of oxygen be \(x\).
The oxidation state of hydrogen is \(+1\).
The molecule is neutral, so the sum is zero:
\[ 2(\text{H}) + 2(\text{O}) = 0 \]
\[ 2(+1) + 2(x) = 0 \]
\[ 2 + 2x = 0 \]
\[ 2x = -2 \]
\[ x = -1 \]
This is because in the peroxide bond \((O-O)\), neither oxygen atom takes electrons from the other; they only gain one electron from the adjacent hydrogen or metal.
Step 4: Final Answer:
The oxidation state of oxygen in peroxides is \(-1\).