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

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Earth and Environmental Science

Earth's Systems

ESS.EES.3.1

Redox Reactions

酸化還元、または 酸化還元反応の際には 電子が原子間を移動します 電子を放出する分子は酸化し 電子を受ける分子は還元され の電気を帯びます 例えば、中性ナトリウムと塩素の原子が イオンになると、ナトリウムは電子を失い、酸化します 塩素は電子を得て、還元されます さらに電子を放出した分子は 還元剤と呼ばれ 電子を受けた分子は 酸化剤と呼ばれます ナトリウムは酸化し、還元剤となります 塩素は還元し、酸化剤となります

Flowers, P., Theopold, K., Langley, R., Robinson, W. R., Clark, M. A., Douglas, M., Choi, J. Section 4.2: 化学反応の分類.化学2eで。OpenStaxです。テキサス州ヒューストン(2019)。

酸化還元反応

酸化還元反応とは、還元剤となる原子から、電子を受け取る酸化剤となる原子へ電子が移動することで、原子の酸化状態を変化させる反応です。この反応で、電子を提供する原子は酸化され（電子を失い）、電子を受け取る原子は還元されます（電子を得ることで少ない正の電荷をもちます）。酸化還元反応におけるエネルギーの動きは、原子が結合電子を引き寄せる力（電気陰性度）に左右されます。酸化剤が還元剤よりも電気陰性であれば、エネルギーが放出されます。しかし、酸化剤が還元剤よりも電気陰性度が少なければ、エネルギーの投入が必要になります。
 
 <h4>還元剤は酸化されます</h4>
 
 酸化とは、電子を失うことでしょうか、それとも電子を得ることでしょうか？専門用語は時に紛らわしいです。OIL、 RIGという頭文字が覚えるためによく使われています。これは「酸化(oxidation)は(is)損失(loss)、還元(reduction)は(is)得る(gain)」の略です。つまり、原子が酸化されると、電子は失われます。還元剤として、酸化された原子は他の原子に電子を移動させ、他の原子を還元させます。OIL RIGを頭に入れておけば、酸化還元反応に関する質問には答えることが可能です。
 
 <h4>電気陰性度とエネルギー</h4>
 
 酸化還元反応は、エネルギーを発生させる場合と必要とする場合があります。原子がより電気陰性度の高い原子に電子を奪われると、エネルギー的に有利な反応となり、エネルギーが放出されます。これは、強い人が弱い人に綱引きで勝つようなもので、電気陰性度の高い原子ほど自分自身へ電子を引き寄せる力が大きいため、非常に理にかなっています。この種の反応の生物学的な例として、細胞呼吸が挙げられます。この反応では、エネルギーが放出され、細胞が利用しやすいエネルギー形態であるATPが生成されます。
 
 その他の酸化還元反応は、エネルギーを放出するのではなく、必要とします。電子が電気陰性度の高い原子から電気陰性度の低い原子に移動する場合、エネルギーを消費しなければなりません。これは、弱い人間が強い人間に綱引きで勝つようなもので、外部からのエネルギーが必要です。生物学的な例は、光合成が挙げられます。この反応では、光というエネルギーの助けにより、電子が水から二酸化炭素へと移動します。

酸化還元反応または酸化還元反応には、ある分子または原子から別の分子または原子への電子の移動が含まれます。原子が電子を獲得すると、別の...

Education

JoVE Core

Biology

生物学

Fundamentals

基礎

Chemistry of Life

生命の化学

KEY TERMS AND CONCEPTS

主要用語と概念

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,...

atomic structure

Atoms and Their Subatomic Particles

Atoms are the smallest units of elements, and they make up all matter. Each atom contains three subatomic particles: protons, neutrons, and electrons. These particles give an atom its mass and its charge. The idea that matter is made of tiny particles goes back to Democritus, a Greek philosopher around 450 B.C. He used the word atomos, which means “indivisible.” The idea was not accepted at the time, but it returned many centuries later. In the 19th century, John Dalton proposed an atomic...

isotopes

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electron behavior

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electron orbital model

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covalent bonds

Electronegativity and Covalent Bond Polarity

Covalent bonds form when two atoms share electrons to fill their valence shells. The way those shared electrons are pulled depends on electronegativity, which is an atom’s ability to attract electrons in a bond. When atoms have similar electronegativities, they form nonpolar covalent bonds. When their electronegativities differ, the bond is polar because the electrons are shared unevenly. The number of covalent bonds an atom can make depends on its valence electrons. Oxygen has six valence...

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...

elements and compounds

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

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pH Scale in Everyday Solutions

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chemical reactions

Atoms, Bonds, and Chemical Reactions

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

Water molecules stick to each other through cohesion. Water is neutral overall, but it is a polar molecule. The oxygen atom in one water molecule has a partial negative charge, and it can bind with a hydrogen atom that has a partial positive charge in another water molecule. This forms a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules, and these bonds give water its cohesive nature. Cohesion helps water form droplets on a surface. Water does not...

adhesion

Water Climbing by Adhesion

Water can climb or stick to surfaces because of adhesion, which is the attraction between different kinds of molecules. In water, this is easy to see on polar surfaces such as glass or cellulose in plants. The positive hydrogen side of water is more attracted to the negative oxygen in silica than to nearby water molecules. This attraction helps explain capillary action. If a narrow glass tube is placed in a beaker of water, water molecules attach to the tube’s surface and the water level rises.

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.

Electron Transfer in Redox | JoVE K12

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JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

Minnesota Academic Standards in Science

Chemistry

3.1.1 9C.3.1.1.1

Alabama Course of Study Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

9-12.B.1.4.b

Florida Department of Education

High School

Life Science

SC.912.L.18

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Electron Transfer in Redox

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