Final answer:
The rules for assigning oxidation numbers in compounds include: assigning an oxidation number of 0 to atoms in their elemental state, assigning an oxidation number equal to the charge of monatomic ions, assigning specific oxidation numbers to fluorine, oxygen, and hydrogen in compounds, and ensuring the sum of oxidation numbers in a species equals its charge.
Step-by-step explanation:
The rules for assigning oxidation numbers in compounds are as follows:
- Atoms in their elemental state are assigned an oxidation number of 0. For example, H₂, Br₂, Na, Be, K, O₂, and P₄ all have an oxidation number of 0.
- Atoms in monatomic ions are assigned an oxidation number equal to their charge. For example, Na⁺ has an oxidation number of +1, and Cl⁻ has an oxidation number of -1.
- Fluorine is assigned a -1 oxidation number in compounds, oxygen is usually assigned a -2 oxidation number (except in peroxide compounds and binary compounds with fluorine), and hydrogen is usually assigned a +1 oxidation number (except when it exists as the hydride ion). For example, in H₂O, the H atoms each have an oxidation number of +1, while the O atom has an oxidation number of -2.
- All other atoms in compounds are assigned an oxidation number so that the sum of the oxidation numbers on all the atoms in the species equals the charge on the species (which is zero if the species is neutral).