oxidation and reduction

• Oxidation states, also known as oxidation numbers, are integral in understanding the degree of oxidation or reduction an atom undergoes within a molecule.
• Oxidation states serve as a foundational concept in the study of redox reactions, where electron transfer is the primary event.
• Elemental Form Rule: Atoms in their elemental form always have an oxidation state of zero.
• Monoatomic Ion Rule: The oxidation state of a monoatomic ion is equivalent to its charge.
• Oxygen Rule: Oxygen predominantly possesses an oxidation state of -2, with exceptions in peroxides where it's -1, and in compounds with fluorine, where it can assume a positive value.
• Hydrogen Rule: Hydrogen generally exhibits an oxidation state of +1, but in metal hydrides, such as LiH, its oxidation state is -1.
• Neutral Compound Rule: For neutral compounds, the sum of the oxidation states of all atoms is zero.
• Polyatomic Ion Rule: For polyatomic ions, the sum of oxidation states corresponds to the ion's charge.
• Fluorine Rule: Fluorine, being the most electronegative element, always has an oxidation state of -1.
• Other Halogens Rule: Other halogens typically exhibit an oxidation state of -1, but when combined with oxygen or fluorine, they can manifest positive oxidation states.
• Oxidation is characterised by a loss of electrons, leading to an increase in the oxidation state.
• Reduction involves a gain of electrons, resulting in a decrease in the oxidation state.
• Redox reactions are those that involve simultaneous oxidation and reduction.
• The substance causing another to be reduced is the oxidising agent, while the substance causing oxidation is the reducing agent.
• Oxidation states help in understanding the electron distribution in molecules and ions.
• In covalent compounds, the more electronegative atom is assigned the negative oxidation state.
• Transition metals often have multiple oxidation states due to the availability of d-orbitals for electron accommodation.
• Understanding oxidation states is pivotal in balancing redox reactions.
• Reducing agent is oxidised in a redox reaction, oxidation state increases, loses electrons and causes the reduction of another species
• Oxidising agent is reduced in a redox reaction, oxidation state decreases, gains electrons and causes the oxidation of another species