Name: protein mapping with 2d gel electrophoresis
Uploaded: 2023-04-30T06:31:06.000Z
Duration: 7 min 31 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Structure and Properties of Matter

HS-PS1-10.

Two-Dimensional Gel Electrophoresis

二维凝胶电泳（2DGE）是一种能够从混合物中分离数千种生物分子的技术。该技术结合了两种不同的分离方法：等电聚焦（IEF）和十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）。该方法通过生物分子的等电点（一种电化学性质）和分子量，在凝胶的两个维度上实现化合物的物理分离。
本视频中的实验流程涵盖了二维凝胶电泳（2DGE）的主要原理，以及对复杂蛋白质溶液组成进行表征的一般操作步骤。在应用部分展示了该技术的三个实例，包括用于疾病发生与发展过程中的生物标志物检测、患者治疗过程的监测，以及翻译后修饰（PTM）蛋白质的研究。

二维凝胶电泳

二维凝胶电泳（2DGE）是一种能够从混合物中分离数千种生物分子的技术。该技术结合了两种不同的分离方法：等电聚焦（IEF）和十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）。该方法通过生物分子的等电点（一种电化学性质）和分子量，在凝胶的两个方向上实现化合物的物理分离。
本视频中的实验流程涵盖了二维凝胶电泳（2DGE）的主要原理，以及对复杂蛋白质溶液组成进行表征的一般操作步骤。在应用部分展示了该技术的三个实例，包括疾病发生与发展过程中的生物标志物检测、对患者治疗过程的监测，以及翻译后修饰（PTM）后蛋白质的研究。
<div class="chapter_text" id="script_0">
二维凝胶电泳（2D凝胶电泳）是一种利用两种不同分离方法的技术，能够从单一混合物中分离数千种蛋白质。其中一种技术——SDS-PAGE（十二烷基硫酸钠聚丙烯酰胺凝胶电泳）——单独使用时无法完全分离复杂的混合物。二维凝胶电泳将SDS-PAGE与第二种方法——等电聚焦（IEF）相结合，后者根据蛋白质的等电点进行分离，从而能够分辨细胞裂解液中几乎所有可能存在的蛋白质。本视频将介绍二维凝胶电泳的原理、通用实验步骤及其在生物医学领域的一些应用。
</div>
<div class="chapter_text" id="script_1">
二维凝胶电泳首先以等电聚焦（IEF）作为第一维分离。每种蛋白质都有一个pH值，称为等电点（pI），在此pH下其净电荷为零。当蛋白质处于电场中时，会向带相反电荷的电极移动。待分析的样品被加样到固定pH梯度（IPG）胶条上，该胶条内嵌有两性电解质分子，这些分子同时含有酸性基团和碱性基团。随后在pH梯度胶条上施加电场，促使蛋白质迁移，直至到达与其pI相匹配的pH区域，此时蛋白质失去净电荷而停止移动。
在进行第二维电泳之前，胶条中已分离的蛋白质需用SDS处理，使其变性并带上均匀的负电荷。处理完成后，将IPG胶条置于聚丙烯酰胺凝胶上。施加电场后，蛋白质向阳极迁移，其中分子量较大的蛋白质在凝胶中移动较慢。
当蛋白质混合物根据等电点（pI）和分子量完成二维分离后，可通过染色方法显现出蛋白质组图谱，并对目标蛋白质进行鉴定。
了解了二维凝胶电泳的基本原理后，接下来我们介绍一个典型的实验室操作流程。
</div>
<div class="chapter_text" id="script_2">
在进行实验之前，必须将蛋白质溶解于培养基中。通过使用变性剂破坏氢键相互作用、非离子型去污剂防止蛋白质电荷改变、还原剂断裂二硫键以及缓冲液，可实现样品中蛋白质的去聚集和溶解。为了去除干扰性的高丰度蛋白质及其他分子，样品需通过离心并收集沉淀物进行连续提取；随后用核酸内切酶处理，该酶可降解可能干扰实验的任何DNA。
蛋白质溶解完成后，通过用胶条清洗液冲洗IPG胶条，并将其倒置晾干以进行准备。每根胶条随后被分配一个胶条支架编号。准备就绪后，细胞提取物以缓慢滑动的方式从负极端向正极端加样至胶条上。为实现再水化，在电极上方及凝胶胶条下方放置湿润的吸水纸；然后将IPG胶条整齐排列于等电聚焦（IEF）仪器中。施加高电流后，蛋白质开始迁移。
</div>
<div class="chapter_text" id="script_3">
完成第一维电泳后，使用制胶装置制备用于SDS-PAGE的凝胶。将IPG胶条倒置放入含有SDS的平衡缓冲液中进行处理。向电泳装置中加入电泳缓冲液以准备电泳。用镊子取出经处理的IPG胶条，将其置于凝胶板上方，并用琼脂糖封胶液密封。然后通过电源施加电场，并持续通电直至迁移最快的蛋白质距离凝胶底部约1 cm。
电泳完成后，需对蛋白质进行显色检测。传统方法是使用考马斯亮蓝或硝酸银染色。感兴趣的蛋白质可从凝胶中转移出来，并通过蛋白质印迹（Western blot）进行分析。
另一种鉴定方法是将蛋白质从凝胶中切下，进行酶解消化，然后通过质谱分析进行鉴定。
</div>
<div class="chapter_text" id="script_4">
现在我们已经回顾了一项实验流程，接下来让我们探讨二维凝胶电泳的一些应用。
该技术最常见的用途之一是鉴定参与疾病发生和发展的分子。将二维凝胶电泳与质谱分析相结合，能够检测患病组织与健康组织相比，特定蛋白质的上调或下调表达。
此外，二维凝胶电泳还可用于监测患者对潜在治疗药物的反应进程。可在给药后的不同时间点采集患者的样本。通过这种方式，结合Western印迹或质谱分析的二维凝胶电泳，能够检测与不良反应（如炎症）相关的蛋白质，或在症状缓解状态下某些蛋白质的缺失情况。
二维凝胶电泳的另一项应用是在翻译后修饰（PTM）研究中分析蛋白质的结构与功能。翻译后修饰是指蛋白质从mRNA翻译完成后所发生的化学修饰。PTM可调控多种生物学功能，包括蛋白质信号传导、基因表达，或导致氧化损伤。二维凝胶电泳对甲基化、乙酰化等修饰具有较高的敏感性，这些修饰可引起蛋白质等电点（pI）和分子量的变化。
</div>
<div class="chapter_text" id="script_5">
您刚刚观看了 JoVE 关于二维凝胶电泳的视频。该视频介绍了该技术的原理、典型的实验步骤，以及其在生物医学领域中的若干应用。
感谢观看！
</div>

双向凝胶电泳（2DGE）是一种能够从混合物中分离数千种生物分子的技术。该技术包括两个不同的步骤……

二维凝胶电泳（2D凝胶电泳）是一种利用两种不同分离方法的技术，能够从单一混合物中分离数千种蛋白质。其中一种技术——SDS-PAGE（十二烷基硫酸钠聚丙烯酰胺凝胶电泳）——单独使用时无法充分分离复杂的混合物。二维凝胶电泳将SDS-PAGE与第二种方法——等电聚焦（IEF）相结合，后者根据蛋白质的等电点进行分离，从而能够分辨细胞裂解液中几乎所有可能存在的蛋白质。本视频将介绍二维凝胶电泳的原理、通用实验步骤以及其在生物医学领域的一些应用。二维凝胶电泳首先以等电聚焦（IEF）作为第一维。每种蛋白质都有一个pH值，称为等电点（pI），在此pH值下其净电荷为零。当蛋白质处于电场中时，会向带相反电荷的电极移动。待分析的样品被加样到固定化pH梯度（IPG）胶条上，该胶条内嵌有两性电解质分子，这些分子同时含有酸性基团和碱性基团。随后在pH梯度胶条上施加电场，促使蛋白质迁移，直至到达与其pI相匹配的pH位置，此时蛋白质失去净电荷而停止移动。在进行第二向电泳之前，将对固定在胶条中的蛋白质进行SDS处理，使其变性并带上均匀的负电荷。处理完成后，将IPG胶条置于聚丙烯酰胺凝胶上。在电场作用下，蛋白质向阳极移动，其中分子量较大的蛋白质在凝胶中的迁移速度较慢。在根据等电点（pI）和分子量对蛋白质混合物进行分离后，通过染色法显现蛋白质组图谱，并鉴定目标蛋白质。在讨论了二维凝胶电泳的原理之后，接下来让我们回顾一个典型的实验室操作流程。在进行实验之前，必须将蛋白质溶解于培养基中。通过使用变性剂破坏氢键相互作用、非离子型去污剂防止蛋白质电荷改变、还原剂断裂二硫键以及缓冲液，可实现样品中蛋白质的去聚集和溶解。为了去除干扰性的高丰度蛋白质及其他分子，样品需通过离心并收集所得沉淀物进行连续提取；随后用核酸内切酶处理，该酶可降解可能干扰实验的任何DNA。蛋白质溶解后，用胶条清洗液冲洗IPG胶条，并倒置晾干。每根胶条随后分配一个胶条支架编号。准备就绪后，将细胞提取物以缓慢的滑动方式从负极端向正极端加样至胶条上。为实现再水化，在电极上方及凝胶胶条下方放置湿润的滤纸；然后将IPG胶条整齐排列于等电聚焦（IEF）仪中。施加高电流，蛋白质开始迁移。完成第一维电泳后，使用制胶装置制备用于SDS-PAGE的凝胶。将IPG胶条倒置放入含有SDS的平衡缓冲液中进行处理。向电泳槽中加入电泳缓冲液以准备电泳装置。用镊子取出经处理的IPG胶条，将其置于凝胶板上方，并用琼脂糖封胶液密封。然后接通电源施加电场，并维持电场直至迁移速度最快的蛋白质距离凝胶底部1 cm处。电泳完成后，必须对蛋白质进行显色。传统方法是使用考马斯亮蓝或硝酸银染色。目的蛋白质可从凝胶中转移出来，并通过蛋白质印迹法（Western blot analysis）进行分析。第二种鉴定方法涉及从凝胶中切下蛋白质，对其进行消化，然后通过质谱分析。 现在我们已经回顾了一项实验流程，接下来让我们探讨一下二维凝胶电泳的一些应用。该技术最常见的用途之一是鉴定参与疾病发生和发展的分子。二维凝胶电泳结合质谱技术，能够检测疾病区域与健康区域相比特定蛋白质的上调或下调。此外，二维凝胶电泳可用于监测患者对潜在治疗药物的反应进程。可在给予治疗后不同时间点采集患者的样本。通过这种方法，结合蛋白质印迹或质谱分析的二维凝胶电泳能够检测与不良反应（如炎症）相关的蛋白质；或检测在症状缓解状态下缺失的蛋白质。二维凝胶电泳的另一个用途是研究翻译后修饰（PTM）对蛋白质结构和功能的影响。翻译后修饰是指蛋白质从 mRNA 翻译完成后对其所进行的化学修饰。PTM 可调控多种生物学功能，包括蛋白质信号传导、基因表达，或导致氧化损伤。二维凝胶电泳对甲基化或乙酰化等修饰具有较高的敏感性，这些修饰可引起等电点（pI）和分子量的变化。您刚刚观看了 JoVE 关于二维凝胶电泳的视频。该视频介绍了该技术的原理、典型的实验步骤，以及其在生物医学领域中的若干应用。感谢观看！

Education

教育

JoVE Science Education

Chemistry

化学

Biochemistry

生物化学

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 onto immobilized pH gradient, or IPG, strips that contain ampholytes, which are molecules with both acidic and basic groups. When an electric field is applied, the proteins move until they reach the pH that matches their pI. At that point, they stop moving because they no longer have a net charge.

Before the second dimension, the proteins are treated with SDS. This step denatures the proteins and gives them a uniform negative charge. The IPG strips are then placed on a polyacrylamide gel for SDS-PAGE. When the electric field is applied, proteins move toward the anode, and larger proteins move more slowly through the gel.

A typical lab workflow begins by solubilizing the protein sample. This is done with chaotropic agents, nonionic detergents, reducing agents, and buffers. The sample is then cleaned by sequential centrifugation and pellet collection, and endonuclease is used to remove DNA that could interfere with the experiment. IPG strips are rinsed, dried, numbered, and loaded with the extract in a slow motion from the negative end to the positive end. Damp blotting paper helps with rehydration before the strips are run on the IEF instrument.

After the first run, the SDS-PAGE gel is prepared in a casting apparatus. The IPG strips are placed face down in SDS-containing equilibration buffer, and then positioned on the gel plates with agarose-sealing solution. Electrophoresis continues until the fastest-moving proteins are about 1 cm from the bottom of the gel. The separated proteins are then visualized with stains such as Coomassie blue or silver nitrate. Proteins of interest can also be transferred for Western blot analysis or excised, digested, and identified by mass spectrometry.

2D gel electrophoresis is widely used in biomedicine. It can help identify proteins involved in disease initiation and progression by comparing diseased and healthy samples. It is also useful for tracking how patients respond to a potential therapeutic drug over time. Another application is the study of posttranslational modifications, or PTMs, which are changes made to proteins after translation from mRNA. Methylation and acetylation can shift both pI and molecular weight, making them detectable with this method.

Protein Mapping with 2D Gel Electrophoresis

protein-mapping-with-2d-gel-electrophoresis

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

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...

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 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

本系列介绍了常用的纯化方法, 如亲和层析, 以及分析方法, 如 MALDI。此外, 视频展示了评估生物相互作用和功能的方法, 如 co-immunoprecipitation 和代谢标记。

See how 2D gel electrophoresis separates proteins by pI and size, then use staining, Western blot, or mass spectrometry to identify biomarkers and PTMs.

Protein Mapping with 2D Gel Electrophoresis | JoVE K12

HS. Chemical Reactions

HS-PS1-11.

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.

Overview

Principles of 2D Gel Electrophoresis

Sample Preparation and Running Isoelectric Focusing

Running SDS-PAGE and Visualization/Analysis

Applications

Summary

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 ...

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, ...

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 ...

Coordination Chemistry Complexes

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
Transition metals are found everywhere from vitamin ...

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.

HS-PS1-1.

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

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 ...

VSEPR Theory and the Basic Shapes

Overview of VSEPR Theory

Valence shell electron-pair repulsion theory (VSEPR theory) enables us to predict the molecular structure, including approximate ...

vsepr-theory-and-the-effect-of-lone-pairs

VSEPR Theory and the Effect of Lone Pairs

Effect of Lone Pairs of Electrons&nbsp;on Molecule Geometry

It is important to note that electron-pair geometry around a central atom is not the same ...

Predicting Molecular Geometry

VSEPR Theory for Determination of Electron Pair Geometries

The following procedure uses VSEPR theory to determine the electron pair geometries and the ...

Molecular Shape and Polarity

Dipole Moment of a Molecule

Polar covalent bonds connect two atoms with differing electronegativities, leaving one atom with a partial positive charge ...

Valence Bond Theory

Overview of Valence Bond Theory

Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals (each containing a single ...

Hybridization of Atomic Orbitals I

The mathematical expression known as the wave function, &#x3C8;, contains information about each orbital and the wavelike properties of electrons in an ...

Hybridization of Atomic Orbitals II

sp3d and sp3d&nbsp;2 Hybridization

To describe the five bonding orbitals in a trigonal bipyramidal arrangement, we must use five of the valence shell ...

Molecular Orbital Theory I

Overview of Molecular Orbital Theory

Molecular orbital theory describes the distribution of electrons in molecules in the same way as the distribution of ...

Molecular Orbital Theory II

Molecular Orbital Energy Diagrams

The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram. For a ...

Molecular Orbital (MO) Theory

Source: Tamara M. Powers, Department of Chemistry, Texas A&#38;M University
This protocol serves as a guide in the synthesis of two metal complexes ...

Intermolecular vs Intramolecular Forces

Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

Molecular and Ionic 
Solids

Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their ...

comparing-intermolecular-forces-melting-point-boiling-point

Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

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.

HS-PS1-3.

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Biological Effects of Radiation

All radioactive nuclides emit high-energy particles or electromagnetic waves. When this radiation encounters living cells, it can cause heating, break ...

determining-rate-laws-and-the-order-of-reaction

Determining Rate Laws and the Order of Reaction

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
All chemical reactions have a specific rate defining the ...

Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.

HS-PS1-8.

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 are ...

Coordination Compounds and Nomenclature

In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For ...

Metal-Ligand Bonds

The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain ...

Communicate scientific and technical information about why the particulate-level structure is important in the functioning of designed materials.

HS-PS2-6.

Protein Mapping with 2D Gel Electrophoresis

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