Question

Define oxidation and reduction in terms of both change in oxidation number and electron loss or gain.

Short answer

Oxidation and reduction can be defined in two ways: (1) Change in oxidation number: oxidation involves an increase in oxidation number, while reduction involves a decrease in oxidation number. (2) Electron loss or gain: oxidation is the loss of electrons, and reduction is the gain of electrons.

Step-by-step solution

Definition 1: Change in Oxidation Number

Oxidation and reduction reactions are chemical transformations that involve changes in the oxidation numbers of atoms. An oxidation reaction results in the increase of the oxidation number for an atom, while a reduction reaction leads to the decrease of the oxidation number.

Definition 2: Electron Loss or Gain

Oxidation and reduction reactions can also be described in terms of electron loss or gain. In electrochemistry, oxidation is a process in which an atom loses one or more electrons, and reduction is a process where an atom gains one or more electrons. Oxidation: Loss of electrons Reduction: Gain of electrons To summarize: Oxidation: 1. Increase in oxidation number 2. Loss of electrons Reduction: 1. Decrease in oxidation number 2. Gain of electrons

Key concepts

Change in Oxidation Number

In the realm of chemistry, understanding the concept of oxidation number is a cornerstone for identifying oxidation-reduction reactions. Oxidation numbers are essentially imaginary charges that an atom would have if all bonds to different atoms were completely ionic.

• **Oxidation** occurs when the oxidation number of an atom increases. This signifies a loss of control over electrons and hints at the atom's increased positive charge or reduced negative charge.
• **Reduction**, conversely, takes place when the oxidation number decreases. This entails a gain of electron control, moving the atom towards a more negative charge, or less positive one.

Keep in mind that oxidation and reduction are always interconnected processes. This interdependence stems from the need for electron balance in a chemical reaction, meaning whenever one atom's oxidation number increases, another's must decrease. By monitoring the change in oxidation numbers, one can effectively decipher the intricacies of a redox reaction.

Electron Transfer

Electron transfer plays a pivotal role in redox (reduction-oxidation) reactions. This principle helps explain the underlying processes governing oxidation and reduction at a fundamental level.

• During **oxidation**, an atom loses electrons, resulting in an increased oxidation state. It's as if the atom donates its electrons to another atom, becoming less negative as it loses electrons.
• Conversely, during **reduction**, an atom gains those electrons, culminating in a decreased oxidation state. The atom accepts electrons, adding to its electron cloud, making it more negative or less positive overall.

This transfer of electrons doesn't happen in isolation. In a chemical reaction, electrons lost by one atom must be gained by another, mirroring the principle of conservation of charge. Understanding electron transfer is crucial for comprehending how atoms interact during chemical reactions, as it influences not only the structure of molecules but also the energy changes within a system.

Redox Reactions

Redox reactions are an essential class of chemical reactions driven by the transfer of electrons between chemical species. These reactions are governed by simultaneous oxidation and reduction processes, hence the name "redox."

• In a redox reaction, you always have one element undergoing **oxidation** (losing electrons) and another experiencing **reduction** (gaining electrons). This electron transfer is the defining feature of all redox reactions.
• Redox reactions are fundamental to both natural processes, like cellular respiration, and technological applications, such as batteries and corrosion.

By understanding redox reactions, you gain insight into the balance and transfer of electrons, which is fundamental to the chemical workings of our world. Recognizing what gets oxidized and what gets reduced in a reaction can help predict the direction and feasibility of chemical processes.