can anyone teach me how to find oxidation number. Please give me correct answer because it is urgent
Answers
Answer:
The oxidation number of a free element is always 0.
The oxidation number of a monatomic ion equals the charge of the ion.
The oxidation number of H is +1, but it is -1 in when combined with less electronegative elements.
The oxidation number of O in compounds is usually -2, but it is -1 in peroxides.
The oxidation number of a Group 1 element in a compound is +1.
The oxidation number of a Group 2 element in a compound is +2.
The oxidation number of a Group 17 element in a binary compound is -1.
The sum of the oxidation numbers of all of the atoms in a neutral compound is 0.
The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.
Explanation:
EXAMPLE:
What is the oxidation number of Cr in CrCl3 ?
Solution:
We use what rules we can to determine the oxidation numbers.
Rule 7 states that the oxidation number of Cl is -1.
We write the oxidation number of the element above its symbol and the total for 3 Cl atoms below the symbol.
This gives Cr-1Cl3
mmmmmmll-3mm.
Rule 8 states the numbers along the bottom must add up to zero. So the number under Cr must be +3.
This gives Cr-1Cl3
mmmmm+3ll-3mm.
There is only one Cr atom, so its oxidation number is +3.
This gives +3Cr-1Cl3
mmmmm+3ll-3mm.
The oxidation number of Cr in CrCl3 is +3.
