Final answer:
To determine the oxidation number for an element, use established rules such as elements in an elemental state having an oxidation number of 0, monatomic ions being equal to their charge, and in compounds, assigning specific values based on the element's typical bonding preferences and overall charge of the compound.
Step-by-step explanation:
The concept of oxidation numbers is crucial in understanding redox (reduction-oxidation) reactions in chemistry. Assigning oxidation numbers to the elements in a molecule is straightforward with the help of established rules. Here is how to determine the oxidation number for an element:
- Atoms in their elemental state have an oxidation number of 0. For instance, O₂ or Na.
- For monatomic ions, the oxidation number is equal to the ion's charge, such as Na⁺ (Na⁺⁺⁺) has an oxidation number of +1.
- In molecules, hydrogen has an oxidation number of +1 when combined with nonmetals, and -1 when it's combined with metals.
- Oxygen has an oxidation number of -2 in most compounds but can differ in cases like peroxides or when bonded to fluorine.
- Fluorine is always assigned an oxidation number of -1, while other halogens are typically -1 except when they are combined with oxygen or other halogens.
- The overall sum of oxidation numbers in a compound should equal the net charge of the compound.
- The most electronegative element in a molecule is assigned a negative oxidation number.
By applying these rules systematically, you can deduce the oxidation numbers of all elements in any given chemical compound.