Name: electron transfer in redox
Uploaded: 2019-03-11T09:21:00.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Earth and Environmental Science

Earth's Systems

ESS.EES.3.1

Redox Reactions

أثناء الأكسدة والاختزال أو تفاعلاتها يتم نقل الإلكترونات بين الذرات. يتأكسد الجزيء الذي يتبرع بالإلكترون ويختزل الجزيء الذي يستقبل الإلكترون. لديه شحنة إيجابية أقل.على سبيل المثال عندما تصبح ذرات الصوديوم والكلور المحايدة أيونات يفقد الصوديوم إلكترونًا. إنه مؤكسد ويكسب الكلور إلكترونًا يصبح مختزل. علاوة على ذلك فإن الجزيء الذي يتبرع بإلكترون يسمى عامل الاختزال في حين أن الجزيء الذي يستقبل الإلكترون هو العامل المؤكسد.مرة أخرى يتم أكسدة الصوديوم لذلك هو عامل الاختزال ويتم اختزال الكلور لذلك فهو عامل مؤكسد.

الزهور ، ب. ، ثيوبولد ، ك. ، لانجلي ، ر. ، روبنسون ، دبليو آر ، كلارك ، إم إيه ، دوغلاس ، إم ، تشوي ، ج. القسم 4.2: تصنيف التفاعلات الكيميائية. في الكيمياء 2 ه. OpenStax. هيوستن ، تكساس (2019).

تفاعلات اأكسدة-اختزال

تعمل تفاعلات الأكسدة و الإختزال على تغيير حالات أكسدة الذرات عن طريق نقل الإلكترونات من ذرة واحدة ، عامل الاختزال ، إلى ذرة أخرى تستقبل الإلكترون ، العامل المؤكسد. هنا ، الذرة التي تتبرع بالإلكترونات تتأكسد _ فهي تفقد الإلكترونات _ و الذرة التي تقبل الإلكترونات تُختزل _ يكون لها شحنة موجبة أقل لأنها تكتسب الإلكترونات. تعتمد حركة الطاقة في تفاعلات الأكسدة والاختزال على قدرة الذرات على جذب إلكترونات الرابطة _ و على سالبيتهاالكهربية. إذا كان العامل المؤكسِد أكثر كهرسلبية من العامل المختِزل ، عندها يتم إطلاق الطاقة. ومع ذلك ، إذا كان العامل المؤكسد أقل كهرسلبية من العامل المختزل ، فإن مدخلات الطاقة مطلوبة.

<h4>عوامل الإختزال تتأكسد</h4>

هل الأكسدة خسارة أو اكتساب للإلكترونات؟ يمكن أن تكون المصطلحات محيرة. يشيع استخدام اختصار OIL RIG للتذكر. إنها تعني الأكسدة هي الخسارة؛ الاختزال هو الربح. لذلك ، إذا تأكسدت الذرة ، فإنها تفقد الإلكترونات. كعامل مختِزل ، تنقل الذرة المؤكسَدة الإلكترونات إلى ذرة أخرى ، مما يؤدي إلى اختزالها. مع وضع OIL RIG في الاعتبار ، يمكن الإجابة على معظم الأسئلة المتعلقة بأعضاء تفاعل الأكسدة والاختزال.

<h4>الكهرسلبية و الطاقة</h4>

تفاعلات الأكسدة والاختزال إما تنتج أو تتطلب الطاقة. إذا فقدت الذرة إلكتروناً إلى ذرة أكثر كهرسلبية ، فهذا تفاعل مفضل من ناحية الطاقة ، ويتم إطلاق الطاقة. هذا في الواقع منطقي للغاية _ مشابه لرجل قوي يربح شد الحبل مع رجل أضعف _ لأن ذرة أكثر كهربية لديها قدرة أكبر على سحب الإلكترونات إلى نفسها. مثال حيوي على هذا النوع من التفاعل هو التنفس الخلوي ، حيث يتم إطلاق الطاقة واستخدامها لإنشاء أدينوسين ثلاثي الفوسفات (ATP) ، وهو شكل من أشكال الطاقة التي يمكن للخلايا استخدامها بسهولة.

تتطلب تفاعلات الأكسدة والاختزال الأخرى طاقة بدلاً من إطلاقها. إذا انتقل الإلكترون من ذرة أكثر كهرسلبية إلى ذرة أقل كهرسلبية ، فيجب استخدام الطاقة. هذا مثل رجل أضعف يفوز في شد الحبل مع رجل أقوى _ يتطلب طاقة من مصدر خارجي. و من الأمثلة البيولوجية على ذلك التمثيل الضوئي ، حيث يتم نقل الإلكترونات من الماء إلى ثاني أكسيد الكربون بمساعدة الطاقة في شكل ضوء.

<h4>نقل غير كامل للإلكترونات</h4>

يمكن أن يحدث تفاعل الأكسدة والاختزال ليس فقط عند نقل الإلكترون ، و لكن أيضا عندما يكون هناك تغيير في مشاركة الإلكترون في الروابط التساهمية! على سبيل المثال ، عندما يتفاعل الميثان و الأكسجين ، ينتجان ثاني أكسيد الكربون والماء. في هذه الحالة ، يتأكسد الكربون الموجود في الميثان. و ذلك لأن الإلكترونات في الميثان يتم تقاسمها بالتساوي بين الكربون و الهيدروجين ، في حين أن الكربون الموجود في ثاني أكسيد الكربون موجب جزئياً لأن الأكسجين يجذب الإلكترونات أكثر مما يفعل الكربون.

تتضمن تفاعلات الأكسدة والاختزال أو الأكسدة والاختزال نقل الإلكترونات من جزيء أو ذرة إلى أخرى. عندما تكتسب ذرة إلكترونا ، فإن ذرة أخرى ...

Education

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علم الأحياء

Fundamentals

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Chemistry of Life

كيمياء الحياة

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

electron transfer in redox

Redox reactions are chemical reactions that involve electron transfer between atoms or molecules. When one particle gains electrons, another must lose them at the same time. That is why oxidation and reduction always happen together.

The two roles in a redox reaction are linked. The atom that is oxidized acts as the reducing agent, or reductant. The atom that is reduced acts as the oxidizing agent, or oxidant. A simple way to remember the ideas is OIL-RIG, which means oxidation is losing electrons and reduction is gaining electrons.

Redox reactions also change oxidation states, or oxidation numbers. An oxidation state is the charge an atom would have if all of its bonds were purely ionic. Checking whether oxidation numbers change in the reactants can help identify a redox reaction.

A sodium and chlorine reaction makes this idea clear. Sodium is oxidized, and chlorine is reduced to form sodium chloride. The process can be shown with half-reactions, which separate the fate of each reactant. In these equations, sodium goes from an oxidation number of 0 to 1+, while chlorine in Cl2 goes from 0 to 1-.

Electron transfer is not always complete. A redox reaction can also happen when the sharing of electrons changes in a covalent bond. Methane and oxygen can react to form carbon dioxide and water. In methane, electrons are shared equally between carbon and hydrogen, but in carbon dioxide the carbon is partially positive because oxygen pulls electrons more strongly. In that reaction, carbon dioxide is oxidized and oxygen is reduced.

Electron Transfer in Redox

the periodic table and organismal elements

the-periodic-table-and-organismal-elements

Periodic Table Basics for Living Things

The periodic table helps explain which elements living things need and how those elements are related. Elements are the smallest units of matter that cannot be broken down further by chemical processes. There are 118 known elements, but not all occur naturally, and even fewer are essential for life. Living matter is made mostly of carbon, nitrogen, hydrogen, and oxygen. Together, these elements make up most of the human body and are also found in all life on Earth. Smaller amounts of calcium,...

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covalent bonds

Electronegativity and Covalent Bond Polarity

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ionic bonds

Ionic Compounds and Electrolytes

Ionic compounds form when atoms gain or lose electrons to reach a more stable electron configuration. The charged particles that result are called ions. Ionic bonds are electrostatic attractions between oppositely charged ions. The most reactive elements include those with one valence electron, such as potassium, and those that need one more valence electron, such as chlorine. Ions that lose electrons become positive cations. Ions that gain electrons become negative anions. Cations and anions...

hydrogen bonds

Hydrogen Bonds in Water

Hydrogen bonds in water are weak attractions between atoms that are already part of other chemical bonds. One atom is electronegative, such as oxygen, and carries a partial negative charge. The other is a hydrogen atom that is bonded to another electronegative atom and has a partial positive charge. These attractions form because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom like oxygen or nitrogen. The electrons in that bond are shared unequally.

van der waals interactions

Intermolecular Forces in Polar Solutions

Intermolecular forces are the attractions and repulsions that act between atoms and molecules. These electrostatic forces come from particles with permanent, partial, or temporary charges. For neutral atoms and molecules, the main types are ion-dipole, dipole-dipole, and dispersion forces, which are together called van der Waals forces. Polar molecules have a partial positive end and a partial negative end. That separation of charge creates a dipole. In water, oxygen is more electronegative...

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Elements, Compounds, and Bonding

Elements and compounds are the two main kinds of pure substances. A pure substance contains only one kind of matter. An element contains only one type of atom. A compound contains two or more types of atoms joined by a chemical bond. Elements can be atomic or molecular, depending on their basic units. They are unique forms of matter with specific chemical and physical properties. Ordinary chemical reactions cannot break an element into a smaller substance. There are 118 elements, but only 98...

molecular shapes

Electron Geometry and Lone Pairs

Electron geometry and lone pairs help explain why molecules take specific shapes. The arrangement of electron groups around a central atom controls the molecular geometry. Valence electrons form bonding pairs, which sit mainly between bonded atoms, or lone pairs, which belong to one atom only. Electron pairs in the valence shell spread out to reduce repulsion. They do this by maximizing the distance between one another. A diatomic molecule has two regions of electron density, and these are...

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chemical reactions

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Chemical reactions rearrange atoms to form new substances. In a reaction, the starting materials are called reactants, and the new substances are called products. The atoms stay the same type and number, but their bonds change, so the substances become different compounds. During a chemical reaction, bonds between atoms break and form again. This means the shared electrons are rearranged. Some reactions happen on their own, while others need an energy source such as heat or light. In biology,...

redox reactions

Redox reactions are chemical reactions that involve electron transfer between atoms or molecules. When one particle gains electrons, another must lose them at the same time. That is why oxidation and reduction always happen together. The two roles in a redox reaction are linked. The atom that is oxidized acts as the reducing agent, or reductant. The atom that is reduced acts as the oxidizing agent, or oxidant. A simple way to remember the ideas is OIL-RIG, which means oxidation is losing...

cohesion

Water Molecules and Surface Tension

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adhesion

Water Climbing by Adhesion

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states of water

Water Phase Changes and Ice Density

Water changes between solid, liquid, and gas states as temperature and molecular motion change. In this lesson, the focus is on how water freezes, melts, vaporizes, and returns to liquid or solid form. The balance between intermolecular forces, which pull molecules together, and kinetic energy, which pushes them apart, controls each state. Water freezes when intermolecular forces become stronger than kinetic energy. Unlike most substances, ice is less dense than liquid water. This happens...

specific heat

How Specific Heat Affects Temperature

Specific heat capacity describes how much energy a substance needs to rise by 1 degree Celsius for each gram. It is often written with calories, grams, and degrees Celsius, but it can also be shown in joules, kilograms, and Kelvin. For water, 1 gram needs 1 calorie to increase by 1°C, which is also written as 1 cal/g-°C or 4186 J/kg/K. Water has a high specific heat capacity, so it takes in a large amount of heat before its temperature changes much. It also gives off a lot of heat when it...

vaporization

Vaporization, Boiling, and Evaporation

Vaporization changes a liquid into vapor when temperature adds enough kinetic energy to overcome intermolecular forces. It is a surface phenomenon, which means it starts at the liquid’s surface. The energy needed to vaporize a set amount of liquid at a given pressure and constant temperature is called the heat of vaporization. Water shows this process clearly. When liquid water is vaporized, it becomes steam. One way this happens is boiling, which occurs when vapor bubbles form beneath the...

solvents

Water as a Biological Solvent

Water acts as a biological solvent in many living systems. A solvent is a substance, usually a liquid, that dissolves another substance called a solute. When a solvent and a solute mix, they form a solution, which is a uniform mixture of both parts. Water is called a universal biological solvent because its polar structure helps it dissolve many other polar compounds. Polarity means that one side of the molecule has a slight positive charge and the other side has a slight negative charge.

carbon skeletons

Carbon Backbones in Biomolecules

Carbon backbones give biological molecules their structure and flexibility. Living things are built from macromolecules that contain carbon atoms, and organic compounds are defined by a carbon backbone. Carbon is tetravalent, so each carbon atom can bond with four other atoms. Its valence electrons are stable, so carbon rarely becomes an ion. As carbon chains get longer, they can form ring structures, double bonds, and branching side chains. Carbon-carbon bonds create the carbon skeleton.

key terms and concepts

Learn how redox reactions move electrons, change oxidation states, and use half-reactions to track sodium, chlorine, methane, and oxygen.

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Minnesota Academic Standards in Science

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Electron Transfer in Redox

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