1. Identify the known oxidation numbers:
* K (Potassium): +1 (Group 1 elements always have +1)
* Cl (Chlorine): -1 (Except in rare cases like Cl₂O₇)
2. Set up an equation:
Let the oxidation number of Pt be 'x'. The sum of the oxidation numbers in a neutral compound must equal zero.
2(+1) + x + 6(-1) = 0
3. Solve for x:
2 + x - 6 = 0
x - 4 = 0
x = +4
Therefore, the oxidation number of Pt in K₂PtCl₆ is +4.
