Name: measuring enzyme reaction rates
Uploaded: 2023-04-30T06:31:30.000Z
Duration: 8 min 7 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Physical Science

Matter and Its Interactions

HS-PS1-5

Enzyme Assays and Kinetics

酵素試金とカイネティクス

酵素反応速度論では、生物に必要な化学反応を促進する生体の酵素の触媒作用について説明します。フォーム製品の基板と呼ばれる分子に作用する酵素。酵素の速度論的パラメーターは直接または間接的に時間をかけて基板または製品の濃度の変化を測定するアッセイによって判別されます。
このビデオでは、酵素反応速度論 (レート方程式を含む) と運動モデルの基本原則をカバーします。酵素試金を支配する概念はまた、典型的な比色定量法に続いて議論します。アプリケーションの説明フェルスター共鳴エネルギー移動 (FRET) 分析、環境では、細胞外酵素を特徴付けるを介して酵素免疫測定法と調査 DNA 修復速度分子プローブの使用します。
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酵素は、生命に不可欠な生化学的触媒です。酵素試金は、酵素の触媒作用の解明、酵素反応の動力学的性質の研究に使用されます。このビデオは酵素反応速度論をカバーし、一般的な手順では、上に行くし、.いくつかのアプリケーションを表示
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<div class="chapter_text" id="script_1">
酵素は、蛋白質、または蛋白質のような分子を基板と呼ばれる反応物分子を対象とします。酵素は、生化学反応の活性化エネルギーを減らします。これにより、低エネルギーの要件と高速料金で発生する反応。
酵素反応は、3 つの基本コンポーネントに分けることができます。最初は、酵素-基質の形成酵素活性部位への基質の結合によって形成される複合体。複合体は、元の要素に分解できます。これは、2 番目の素の反応です。また、複雑な製品を形成し、酵素、3 番目の素反応を回復できます。
素反応の反応速度論は、基本レート法方程式によって与えられます。率法の方程式は、反応と速度定数の集積率を与えます。素反応のそれぞれは、独自の速度定数の個々 の料金法式を持ちます。これらの方程式は、ミカエリス-メンテン型方程式として知られているキネティック モデルまで蒸留することができます。これは、基質濃度の面での反応速度を与えることが実験的に決定します。ミカエリス-メンテン型方程式を用いた酵素反応のいくつかの一般的な傾向を識別できます。高基質濃度で飽和点に達すると、Vmax と呼ばれます。ここでは、率は全酵素濃度による制限は、製品に変換する酵素、基質分子の数あたりの時点、kcat として知られています。ミカエリス-メンテン型の速度論 kcat は反応速度を支配する 2 つの定数のいずれかです。その他の定数、KM は、親和性の定数と呼ばれます。KM は、反応速度が Vmax の半分に相当濃度と同じもです。高い親和性を持つ酵素が低い KM を持っているし、低い親和性をもつ酵素が高い KM を持っているし、Vmax に到達する時間がかかる中、高速 Vmax に達する。Kcat、KM を知って比較する酵素のことができます。これを行うには、酵素の効率と呼ばれる比率を使用します。高い kcat と低い KM 下 kcat ながら低い高い KM の結果の高い効率の結果します。
酵素反応速度論を解明するために使用する要素は、実験的に決定する必要があります。これらの試金は通常、制御された環境で酵素と基質ソリューションを混合することによって実行されます。観測は、基板、製品、または時間経過に伴って副生成物の濃度の変化を測定することによって作られています。
濃度の経年変化は、反応速度を決定するために使用されます。速度を決定するために複数の濃度で率データを取得する必要があります。占める割合バーク プロットとして知られている逆の初期濃度と逆の初期速度のプロットが直線の場合、反応はミカエリス-メンテン型の速度論に従います。斜面と直線の切片は、KM と Vmax は、kcat と酵素の効率を計算する使用できますの速度論的パラメーターの決定を許可します。
今では酵素反応速度論の原則を議論されている、典型的な酵素試金の実行方法を見てみましょう。
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<div class="chapter_text" id="script_2">
この手順では、比色定量法が示されています。最初のステップは、蛋白質濃度と吸光度を関連付ける標準的な曲線を生成します。濃度既知のソリューションは、コントロールのサンプルと一緒に用意しています。標的タンパク質と反応する開発者ソリューションは、着色された化合物を生成する追加されます。吸光度が測定し、標準曲線の生成を濃度に対してプロットします。
アッセイを実行するには、知られている基質濃度は酵素の適切な量と共に用意しています。酵素と基質は混合し、インキュベートする指定された時間間隔を許可しました。緩衝溶液と加熱ブロック pH と温度を管理します。焼入エージェントを追加して、反応を停止します。開発者ソリューションは反応に追加し、混合します。キュベットに配置されます、ソリューションと吸光度を測定します。基板の消費量は、標準曲線を測定した吸光度を比較することによって決まります。収集したデータを使用して、初期の反応速度は時間の経過と共に濃度をプロットすることによって決定されます。最後に、速度データと濃度、ミカエリス-メンテン型プロットが行われます。回転数と酵素の効率など酵素の動力学的性質の決定が可能になります。
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<div class="chapter_text" id="script_3">
今では試金プロシージャを確認しましたところ、その他さまざまな試金が実行されると、アプリケーションを見てみましょう。
この手順フレット分析を使用して蛋白質のペプチド結合を加水分解プロテアーゼの動力学を調査します。基板の消費と生産の継続的な定量分析を可能にする、反応速度の測定を支援、これらの排出量を測定できます。
酵素試金は、環境中の細胞外酵素活性レベルを決定する環境科学で使用できます。水、土壌、堆積物を環境から収集し、実験室で処理できます。これらの材料の細胞外の酵素活性は、酵素試金を使用して特徴付けることが。これは、環境が有機材料を処理する方法を理解するための便利なツールです。
細胞の DNA 修復機構は、核で見つかり酵素の速度論を研究することによって評価できます。ユニークな DNA シーケンスにバインドされたときのみ蛍光を発する蛍光の分子ビーコンを用いた DNA 損傷や損害、その酵素を削除します率が測定できます。レベルの DNA 修復は、蛍光に分類された胸の谷間製品を検出することにより、リアルタイムで測定できます。
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<div class="chapter_text" id="script_4">
酵素反応速度論とアッセイのゼウスのビデオを見てきただけ。このビデオ酵素反応速度論を説明した、分析概念について説明、一般的な手順を行って、いくつかのアプリケーションを説明しました。
見てくれてありがとう!
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Enzyme kinetics describes the catalytic effects of enzymes, which are biomolecules that facilitate chemical reactions necessary for living organisms. ...

酵素は、生命に不可欠な生化学的触媒です。酵素アッセイは、酵素反応の速度論的特性を研究するために使用され、酵素の触媒効果を解明します。このビデオでは、酵素の動態とアッセイを取り上げ、一般的な手順を説明し、いくつかのアプリケーションを紹介します。酵素は、基質と呼ばれる特定の反応物に作用するタンパク質、またはそれほど多くはないRNAです。酵素は、生化学反応を開始するために必要な活性化エネルギーを減らし、反応をより速い速度で起こします。酵素反応は、3つの基本要素に分けることができます。第一は、基質の酵素活性部位への結合によって形成される酵素 - 基質複合体の形成である。複合体は、元の成分に分解できます。これが2番目の基本反応です。あるいは、複合体は生成物を形成し、酵素、すなわち第三の基本反応を回復させることができる。素反応の動力学は、素速度法則方程式によって与えられます。レート法則方程式は、反応物の濃度とレート定数でレートを示します。各基本反応には、独自の速度定数を持つ個別の速度法則方程式があります。これらの方程式は、Michaelis-Menten方程式として知られる動力学モデルに蒸留できます。これにより、基質濃度に関する反応速度が得られます。これは実験的に決定できます。酵素反応の一般的な傾向は、Michaelis-Menten方程式を使用して特定できます。基板濃度が高いと、Vmaxと呼ばれる飽和点に達します。ここで、速度は総酵素濃度と、酵素が所定の時間あたりに生成物に変換する基質分子の数(kcatとも呼ばれます)によって制限されます。Michaelis-Menten kinetics では、kcat は反応速度を支配する 2 つの定数の 1 つです。もう 1 つの定数である KM は、親和定数として知られています。KMは、反応速度が2分の1Vmaxに相当する濃度にも相当します。親和性が高い酵素はKMが低く、Vmaxに早く到達しますが、親和性が低い酵素はKMが高くなり、Vmaxに到達するのに時間がかかります。kcatとKMを知ることで、酵素を比較することができます。これを行うには、酵素効率と呼ばれる比率を使用します。kcat が高く、KM が低いほど効率が高くなり、kcat が低く KM が高いほど効率が低くなります。酵素動態を解明するための因子は、実験的に決定する必要があります。これらのアッセイは、通常、制御された環境で酵素と基質溶液を混合することによって実行されます。観察は、基質、生成物、または副生成物の濃度の時間に対する変化を測定することによって行われます。時間の経過に伴う濃度の変化は、反応速度を決定するために使用されます。速度論を決定するには、複数の濃度で速度データを取得する必要があります。逆初期速度と逆初期濃度のプロット (Lineweaver-Burk プロット) が線形である場合、反応は Michaelis-Menten 速度論に従います。ラインの傾きと切片により、速度論パラメータKMとVmaxの決定が可能になり、これを使用してkcatと酵素効率を計算できます。酵素動態の原理について説明したところで、一般的な酵素アッセイがどのように行われるかを見てみましょう。この手順では、比色アッセイが実証されます。?最初のステップは、吸光度と基質濃度を相関させる標準曲線を生成することです。既知の濃度の溶液をコントロールサンプルと共に調製します。基質と反応する現像液を添加して、着色化合物を生成します。吸光度を測定し、濃度に対してプロットして標準曲線を生成します。アッセイを実施するために、既知の濃度の基質を適切な量の酵素とともに調製します。酵素と基質を混合し、設定された時間間隔でインキュベートします。pHと温度は、緩衝液と加熱ブロックで制御されます。反応を止めるために焼入れ剤を添加します。その後、開発者ソリューションが反応に追加され、混合されます。次に、溶液をキュベットに入れ、吸光度を測定します。消費される基質の量は、測定された吸光度を標準曲線と比較することによって決定されます。収集したデータを使用して、経時的な濃度をプロットすることにより、初期反応速度を決定します。最後に、速度データと濃度を使用して、Michaelis-Mentenプロットが作成されます。これにより、代謝回転数や酵素効率などの酵素の速度論的特性を決定することができます。アッセイの手順を確認したので、アッセイの他の方法とその応用について見てみましょう。この手順では、FRET分析を使用して、タンパク質のペプチド結合を加水分解するプロテアーゼの動態を研究します。これらの排出量を測定できるため、基質の消費と生産の連続的かつ定量的な分析が可能になり、反応速度の決定に役立ちます。酵素アッセイは、環境科学において、環境中の細胞外酵素活性のレベルを決定するために使用できます。水、土壌、堆積物は、環境から収集し、実験室で処理することができます。これらの材料の細胞外酵素活性は、酵素アッセイを用いて特徴付けることができます。これは、環境が有機物をどのように処理するかを理解するのに役立つツールです。細胞のDNA修復メカニズムは、核に見られる酵素の動態を研究することで評価できます。酵素がDNAの損傷または損傷を除去する速度は、蛍光分子ビーコンを使用して測定できます。蛍光分子ビーコンは、固有のDNA配列に結合した場合にのみ蛍光を発します。DNA修復のレベルは、蛍光標識された切断産物を検出することにより、リアルタイムで測定できます。JoVEの酵素動態とアッセイに関するビデオをご覧になりました。このビデオでは、酵素動態について説明し、アッセイの概念を取り上げ、一般的な手順を説明し、いくつかのアプリケーションについて説明しました。ご覧いただきありがとうございます!

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Biochemistry

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measuring enzyme reaction rates

Enzyme reaction rates can be measured with assays that track how substrate or product levels change over time. Enzymes are proteins, or sometimes RNAs, that speed up chemical reactions by lowering the activation energy needed to start them. They act on a specific substrate and help form a product that supports life processes.

Enzymatic reactions are often described in three steps. First, the substrate binds to the enzyme active site and forms an enzyme-substrate complex. That complex can fall apart again, or it can make product and release the enzyme. Each step has its own rate law and rate constant.

These steps are often simplified with the Michaelis-Menten equation. This model links reaction rate to substrate concentration and helps show general enzyme trends. At high substrate levels, the reaction reaches a saturation point called V max. The turnover number, or k cat, describes how many substrate molecules one enzyme converts per unit time. KM is the concentration where the rate is half of V max, and it also reflects affinity. A lower KM usually means higher affinity, while a higher KM usually means lower affinity. The ratio of k cat and KM is used as enzyme efficiency.

To find these values, scientists run assays in a controlled setting. They mix enzyme and substrate and measure changes in substrate, product, or byproducts over time. Reaction rates are collected at multiple substrate concentrations. If a Lineweaver-Burk plot, which graphs inverse initial rate against inverse initial concentration, is linear, the reaction follows Michaelis-Menten kinetics. The slope and intercept can then be used to determine KM and V max, and these values help calculate k cat and enzyme efficiency.

A common lab method is a colorimetric assay, which uses color to measure concentration. First, a standard curve is made from known concentrations and a control sample. A developer solution reacts with the substrate and creates a colored compound. Absorbance is measured and plotted against concentration to build the curve.

For the assay, a known amount of substrate and enzyme is prepared. The two are mixed and incubated for a set time. Buffer solutions and heating blocks keep pH and temperature controlled. A quenching agent stops the reaction, and developer solution is added. The samples are placed in cuvettes, and absorbance is measured. The amount of substrate used is found by comparing the result to the standard curve. Initial rates are then plotted over time, and the Michaelis-Menten plot is used to determine turnover number and enzyme efficiency.

Other assay methods can track reactions in real time. FRET, or Förster resonance energy transfer, can measure a protease breaking a peptide bond in a protein. The emitted signal can be monitored continuously, which helps quantify substrate consumption and product formation. Enzyme assays are also used in environmental science to measure extracellular enzyme activity in waters, soils, and sediments. These samples are processed in the lab to help explain how the environment breaks down organic material.

Enzyme kinetics can also be used to study DNA repair. Enzymes in the nucleus remove DNA lesions, or damage, and their activity can be followed with fluorescent molecular probes. These beacons fluoresce only when they bind specific DNA sequences. The fluorescent cleavage products make it possible to measure DNA repair in real time.

Measuring Enzyme Reaction Rates

dialysis: diffusion based separation

Dialysis for Buffer Exchange in Biochemistry

Dialysis is a common biochemistry technique for buffer exchange and desalting. It separates molecules by diffusion through a semipermeable membrane, which lets small molecules pass while holding larger biomolecules inside the sample. The membrane is the key part of the setup. Its pores create a molecular weight cutoff, so a membrane such as a 10 kDa membrane usually keeps molecules larger than 10 kilodaltons inside. This cutoff is not exact, because membranes have a range of pore sizes.

enzyme assays and kinetics

Enzyme reaction rates can be measured with assays that track how substrate or product levels change over time. Enzymes are proteins, or sometimes RNAs, that speed up chemical reactions by lowering the activation energy needed to start them. They act on a specific substrate and help form a product that supports life processes. Enzymatic reactions are often described in three steps. First, the substrate binds to the enzyme active site and forms an enzyme-substrate complex. That complex can fall...

maldi-tof mass spectrometry

How MALDI-TOF Reads Biomolecules

MALDI-TOF mass spectrometry reads biomolecules by using a laser, a matrix, and a time-of-flight analyzer. MALDI, or matrix-assisted laser desorption ionization, helps fragile molecules keep their structure while they are moved into the mass analyzer. The analyzer then separates compounds based on size and charge. In MALDI, the sample is mixed into a matrix, usually an organic compound with aromatic and conjugated double bonds. A laser pulse strikes the spot, and the matrix absorbs most of the...

tandem mass spectrometry

Tandem Mass Spectrometry for Biomolecule Analysis

Tandem mass spectrometry is used to isolate a biomolecule and break it into smaller pieces so its makeup can be studied. Because biomolecules often have large, complex structures, it can be hard to identify their molecular composition and sequence from a single measurement. By linking mass spectrometers in series, the technique first selects one ion and then analyzes the fragments it produces. The process starts with an ion source that converts the sample into ions. A mass analyzer then...

protein crystallization

Protein Crystals for Structure Analysis

Protein crystals help scientists study protein structure and function. A crystal is a solid lattice made from purified protein molecules. These crystals are useful in structural biology because they reveal details that methods like mass spectrometry and SDS-PAGE cannot show on their own. Protein crystallization is paired with recombinant protein expression and x-ray diffraction to support this work. The process starts with a large amount of very pure protein. Researchers often make that...

chromatography-based biomolecule purification methods

chromatography-based-biomolecule-purification-methods

Protein Purification with SEC and IMAC

Protein purification with size-exclusion chromatography and affinity chromatography helps isolate biomolecules from complex mixtures. These methods are common in biochemistry because purified samples are needed before a biomolecule’s properties and activity can be studied. The video focuses on the principles behind size-exclusion chromatography, affinity chromatography, and immobilized metal affinity chromatography, or IMAC. Size-exclusion chromatography, or SEC, separates molecules by size. A...

two-dimensional gel electrophoresis

Protein Mapping with 2D Gel Electrophoresis

Protein mapping with 2D gel electrophoresis separates complex protein mixtures across two steps. The method combines isoelectric focusing, or IEF, with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or SDS-PAGE. Together, these methods can resolve thousands of biomolecules from a single sample by their isoelectric point and molecular weight. The first dimension is IEF. Each protein has an isoelectric point, or pI, which is the pH where its net charge is zero. Proteins are loaded...

metabolic labeling

Tracking Cell Chemistry with Metabolic Labels

Metabolic labeling tracks cell chemistry by using chemical analogs that cells take up and build into biomolecules. These labels help scientists follow biochemical changes and modifications inside cells. The labeled products can then be studied with tools such as SDS-PAGE and NMR to learn more about metabolic pathways. Several labeling strategies are shown here. Isotopic labeling uses analogs that match the natural molecule but contain uncommon isotopes, such as carbon-13 and nitrogen-15 in an...

electrophoretic mobility shift assay (emsa)

electrophoretic-mobility-shift-assay-emsa

Detecting Protein-DNA Binding by EMSA

Electrophoretic mobility shift assay, or EMSA, is a biochemical method used to detect binding between proteins and nucleic acids. It is also called a gel shift assay. The test compares how a labeled nucleic acid moves through a gel before and after it binds a protein. EMSA is used to see whether a specific protein binds to a specific nucleic acid. First, the nucleic acid is labeled to make a probe. The transcript describes radioactive phosphorus-32 as a common label. The probe is then mixed...

photometric protein determination

Measuring Protein Concentration with Absorbance

Measuring protein concentration with absorbance is a key step in many biochemical assays. Photometric methods use the fact that samples with more light-absorbing material transmit less light. Because concentration and absorption are directly related, this makes it possible to measure an unknown sample. The core idea comes from the Beer-Lambert Law. This law states that the concentration of a light-absorbing species is proportional to its absorbance. The video also introduces the Bradford assay...

density gradient ultracentrifugation

Sucrose Gradient Separation in an Ultracentrifuge

Sucrose gradient separation in an ultracentrifuge is a lab method for isolating cell parts and biomolecules. It uses differences in density to make particles sink or rise in a liquid. A high-speed ultracentrifuge speeds up this process so components can be separated without destroying them. The basic idea starts with a suspension, which is particles mixed in a liquid solvent. Particles that are denser than the solvent sediment, while less dense particles float. A rotor inside the...

co-immunoprecipitation and pull-down assays

co-immunoprecipitation-and-pull-down-assays

Protein Interaction Capture Methods in Cells

Co-immunoprecipitation and pull-down assays are laboratory methods used to capture stable protein-protein interactions. Protein-protein interactions help control many biological functions, but many of them have not yet been identified. These assays are related to immunoprecipitation, which isolates a target protein from a mixed sample using an antibody. In co-immunoprecipitation, or CoIP, an antibody binds the target protein, and that protein is already attached to another protein that the...

reconstitution of membrane proteins

Membrane Proteins in Liposome Models

Membrane proteins can be moved into liposome models so their function can be studied outside a cell. Reconstitution means restoring an isolated biomolecule to a working form. For membrane proteins, that usually means placing a purified protein into an artificial lipid membrane. Cell membranes are made mainly of phospholipids and membrane proteins. The phospholipids form a bilayer with hydrophilic phosphate heads facing water and hydrophobic fatty acid tails facing inward. Some membrane...

f&#246;rster resonance energy transfer (fret)

FRET as a Molecular Ruler in Cells

Föster resonance energy transfer, or FRET, is a way to study close-range biochemical interactions using light-emitting molecules. A donor fluorophore can pass energy to an acceptor fluorophore when their emission and absorption spectra overlap. This transfer happens only when the pair is very close together, usually within 10 nm. Because FRET depends on distance, it is often called a molecular or spectroscopic ruler. The strength of the signal is measured as FRET efficiency, which describes...

surface plasmon resonance (spr)

SPR Biosensors for Tracking Binding Kinetics

Surface plasmon resonance, or SPR, is a way to track biomolecular binding on a label-free biosensor. It is used to measure molecular affinity, kinetics, specificity, and concentration. The method works with a thin metal layer on a prism, where changes in reflected light reveal interactions in real time. SPR sensors use a thin layer of a noble metal on the face of a prism. Light is reflected from the prism-metal interface into a photodetector. At one specific angle, called the surface plasmon...

biochemistry

このコレクションでは、親和性クロマトグラフィーなどの一般的に使用される精製方法や、MALDI-TOFなどの分析方法について紹介します。さらに、共同免疫沈降法や代謝標識法など、生体分子の相互作用や機能を評価する方法も紹介します。

Measure enzyme reaction rates with assays, standard curves, and Michaelis-Menten plots. Learn how kcat, KM, colorimetric assays, FRET, and DNA repair studies work.

Measuring Enzyme Reaction Rates | JoVE K12

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-5.

Life Science

Structure and Function

HS-LS1-1.

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-6.

Inheritance and Variation of Traits

HS-LS3-1.

Overveiw

Principles of Enzyme Kinetics

Enzyme Assay

Applications

Summary

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Atomic Structure

All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons, neutrons, and ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Electronic Structure of Atoms


An atom comprises protons and neutrons, which are contained inside the dense, central&#160;core called the nucleus, with electrons present around the ...

Electron Behavior

Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside in ...

Electron Orbital Model

Orbitals are the areas outside of the atomic nucleus where electrons are most likely to reside. They are characterized by different energy levels, shapes, ...

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

Electron Configurations

Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Halogens

Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. ...

Noble Gases


The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name &ldquo;noble&rdquo; because they were ...

Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms. [Clarification Statement: Examples of properties that could be predicted from patterns could include reactivity of metals, types of bonds formed, numbers of bonds formed, and reactions with oxygen.] [Assessment Boundary: Assessment is limited to main group elements. Assessment does not include quantitative understanding of ionization energy beyond relative trends.]

HS-PS1-1

Atomic Number and Mass Number

The number of protons in the nucleus of an atom is its atomic number (Z). This is the defining trait of an element. Its value determines the identity of ...

Chemical Reactions

A chemical reaction is a process by which the bonds in the atoms of substances are rearranged to generate new substances. Matter cannot be created or ...

Chemical Equations

Chemical equations represent the identities and relative quantities of substances involved in a chemical reaction. The substances undergoing reaction are ...

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Predicting Reaction Outcomes

Kinetics describes the rate and path by which a reaction occurs. In contrast, thermodynamics deals with state functions and describes the properties, ...

Chemical Reactions in Aqueous Solutions

Chemical substances interact in many different ways. Certain chemical reactions exhibit common patterns of reactivity. Due to the vast number of chemical ...

Multi-Step Reactions

Chemical reactions often occur in a stepwise fashion involving two or more distinct reactions taking place in a sequence. A balanced equation indicates ...

Reaction Mechanisms

Chemical reactions often occur in a stepwise fashion, involving two or more distinct reactions taking place in a sequence. A balanced equation indicates ...

Rate-Determining Steps

Relating Reaction Mechanisms
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest ...

Reaction Stoichiometry

A balanced chemical equation provides a great deal of information in a very succinct format. Chemical formulas provide the identities of the reactants and ...

Limiting Reactant

The relative amounts of reactants and products represented in a balanced chemical equation are often referred to as stoichiometric amounts. However, in ...

Reaction Yield

The theoretical yield of a reaction is the amount of product estimated to form based on the stoichiometry of the balanced chemical equation. The ...

stoichiometry-product-yield-and-limiting-reactants

Stoichiometry, Product Yield, and Limiting Reactants

Chemical equations represent how a chemical reaction proceeds from reactants to products through physical or chemical change using chemical formulas.
...

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Preparation of 25% v/v Ethylenediamine in Deionized WaterExpand
	Here, we show the laboratory ...

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Synthesis of tris(ethylenediamine)nickel chlorideExpand
	In this lab, you will combine nickel ...

Balancing Redox Equations

Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or ...

Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties. [Clarification Steatement: Examples of chemical reactions could include the reaction of sodium and chlorine, of carbon and oxygen, or of carbon and hydrogen.] [Assessment Boundary: Assessment is limited to chemical reactions involving main group elements and combustion reactions.]

HS-PS1-2

What is Matter?

The substance of the universe&#8212;from a grain of sand to a star&#8212;is called matter. Scientists define matter as anything that occupies space and ...

Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. [Clarification Statement: Emphasis is on understanding the strengths of forces between particles, not on naming specific intermolecular forces (such as dipole-dipole). Examples of particles could include ions, atoms, molecules, and networked materials (such as graphite). Examples of bulk properties of substances could include the melting point and boiling point, vapor pressure, and surface tension.] [Assessment Boundary: Assessment does not include Raoult’s law calculations of vapor pressure.]

HS-PS1-3

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

types-of-chemical-reactions-anabolic-and-catabolic

Types of Chemical Reactions: Anabolic and Catabolic

The first law of thermodynamics holds that energy can neither be created nor destroyed&#8212;it can only change form. An organism&#39;s essential function ...

types-of-chemical-reactions-exchange-and-reversible

Types of Chemical Reactions: Exchange and Reversible

An exchange reaction is a chemical reaction in which both synthesis and decomposition occur, chemical bonds are both formed and broken, and chemical ...

Energy Transfer in Chemical Reactions

Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ...

Arrhenius Plots

The Arrhenius equation relates the activation energy and the rate constant, k, for chemical reactions. In the Arrhenius equation, k = Ae&#8722;Ea/RT, R is ...

Reaction Rate

The rate of reaction is the change in the amount of a reactant or product per unit time. Reaction rates are therefore determined by measuring the time ...

Measuring Reaction Rates

Polarimetry finds application in chemical kinetics to measure the concentration and reaction kinetics of optically active substances during a chemical ...

factors-influencing-the-rate-of-chemical-reactions

Factors Influencing the Rate of Chemical Reactions

A variety of factors influence the rate of chemical reactions. For a chemical reaction to happen, atoms must collide with enough energy to overcome the ...

Catalysis

The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed ...

Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy. [Clarification Statement: Emphasis is on the idea that a chemical reaction is a system that affects the energy change. Examples of models could include molecular-level drawings and diagrams of reactions, graphs showing the relative energies of reactants and products, and representations showing energy is conserved.] [Assessment Boundary: Assessment does not include calculating the total bond energy changes during a chemical reaction from the bond energies of reactants and products.]

HS-PS1-4

Measuring Enzyme Reaction Rates

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