Final answer:
To determine oxidation numbers in a molecule, apply several rules such as hydrogen typically being +1, oxygen -2 (except in peroxides, or when bound to fluorine), and halogens generally -1 (unless combined with oxygen), ensuring that the sum of oxidation numbers equals the charge on the molecule or ion.
Step-by-step explanation:
To find the oxidation numbers of atoms in a molecule containing oxygen (O), hydrogen (H), and a halogen, you can follow these general rules:
- Hydrogen is usually assigned an oxidation number of +1 except when it forms compounds with metals (where it can be -1).
- Oxygen is typically assigned an oxidation number of -2, but in peroxides, it has an oxidation number of -1. When bonded to fluorine, oxygen can have a positive oxidation number.
- Halogens such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) usually have negative oxidation numbers (-1), but when they are combined with oxygen, their oxidation numbers can be positive.
- The sum of oxidation numbers in a neutral molecule must be 0, and in a polyatomic ion, it must equal the ion's charge.
Examples: In H2O, hydrogen has an oxidation number of +1 and oxygen has an oxidation number of -2. For halogens in a molecule like HCl, hydrogen would still be +1, while chlorine would be -1. In polyatomic ions like chlorate (ClO3-), chlorine would have an oxidation number of +5 and oxygen would have -2.