Name: how intermolecular forces affect matter
Uploaded: 2025-05-22T09:05:33.000Z
Duration: 2 min 56 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-3

intermolecular-forces-and-physical-properties

Intermolecular Forces and Physical Properties

تسمى التفاعلات الكهروستاتيكية الموجودة بين الجزيئات بالقوى بين الجزيئات. تؤثر هذه القوى الجذابة على الخصائص الفيزيائية المختلفة ، مثل نقطة الانصهار ونقطة الغليان والذوبان.
تشمل الأنواع الثلاثة الرئيسية للقوى بين الجزيئات التفاعلات الأيونية ثنائية القطب القوية بين الأيونات والجزيئات القطبية ، والتفاعلات ثنائية القطب ثنائية القطب بين الجزيئات القطبية ، وأخيرا ، الأضعف على الإطلاق - قوى التشتت - الموجودة في جميع الجزيئات ، القطبية وغير القطبية.
التفاعلات بين الأيونات وثنائيات القطب شائعة في الحلول. عندما يذوب مركب أيوني مثل كلوريد الصوديوم في مذيب قطبي مثل الماء ، تتماشى الأيونات مع الأطراف المشحونة بشكل معاكس لجزيئات الماء ، مما يسمح بأقصى قدر من الجاذبية الكهروستاتيكية.
بدلا من ذلك ، يتم عرض التفاعلات ثنائية القطب وثنائية القطب بواسطة الجزيئات القطبية ذات ثنائيات الأقطاب الدائمة ، حيث تتفاعل الطرف الموجب لجزيء واحد إلكتروستاتيكيا مع الطرف السالب للجزيء المجاور.
عندما تنجذب ذرة هيدروجين مرتبطة بالأكسجين أو النيتروجين أو الفلور إلى الذرة الكهربية لجزيء مجاور، تتشكل رابطة هيدروجينية — نوع خاص من التفاعل ثنائي القطب وثنائي القطب. والجدير بالذكر أن المركبات القادرة على الترابط الهيدروجيني تظهر نقاط انصهار وغليان عالية.
قوى التشتت ناتجة عن ثنائيات الأقطاب المؤقتة وتميل إلى الزيادة مع الكتلة المولية. تحتوي الذرات ذات الكتل الأعلى على المزيد من الإلكترونات وسحب الإلكترون الأكبر ، مما يؤدي إلى زيادة قوى التشتت. نتيجة لذلك ، هناك حاجة إلى مزيد من الطاقة للتغلب على قوى الجذب بين الذرات المجاورة ، مما يؤدي إلى ارتفاع نقاط الغليان والانصهار.
وهذا ما يفسر سبب زيادة نقاط غليان الألكان مع كتلتها المولية.
ومع ذلك ، فإن الكتلة المولية ليست المعيار الوحيد. على الرغم من وجود نفس الكتل ، إلا أن n-pentane لديه نقطة غليان أعلى من neopentane بسبب زيادة مساحة السطح المتاحة لقوى التشتت.
القوى بين الجزيئات ضرورية أيضا في تحديد الذوبان. السوائل من نفس النوع وحجم القوى بين الجزيئات ، مثل الماء والإيثانول ، قابلة للذوبان تماما بجميع النسب أو قابلة للامتزاج.
في المقابل ، فإن السوائل مثل الهكسان والماء ، بأنواع وأحجام مختلفة من القوى بين الجزيئات ، غير قابلة للذوبان في معظم النسب أو غير قابلة للامتزاج.
بشكل عام ، تكون القوى بين الجزيئات ضعيفة نسبيا لأن الشحنات الصغيرة أو الجزئية تتفاعل عبر مسافات كبيرة.

القوى بين الجزيئية والخصائص الفيزيائية

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القوى بين الجزيئية هي قوى تجاذبية موجودة بين الجزيئات. تحدد هذه القوى العديد من الخصائص الكلية للمواد، مثل نقاط الانصهار، ونقاط الغليان، وقابلية الذوبان (الامتزاج) للمواد. على سبيل المثال، يُظهر السائل ذو درجة الغليان العالية، مثل الماء (H2O، درجة حرارة 100 درجة مئوية)، قوى بين الجزيئية أقوى مقارنة بالسائل ذو درجة غليان منخفضة، مثل الهكسان (C6H14، درجة حرارة 68.73 درجة مئوية). تشمل الأنواع الثلاثة للتفاعلات بين الجزيئية: (1) قوى الأيونات ثنائية القطب، (2) التفاعلات ثنائية القطب (ثنائية القطب)، و(3) قوى فان دير فالس، والتي تشمل قوى تشتت لندن.

<h4>1. قوى الأيون-ثنائي القطب</h4>

قوى الأيون-ثنائي القطب هي عوامل الجذب الكهروستاتيكية بين الأيون وثنائي القطب. وهي شائعة في المحاليل وتلعب دورًا مهمًا في إذابة المركبات الأيونية، مثل KCl، في الماء. تتناسب قوة التفاعلات الأيونية ثنائية القطب بشكل مباشر مع i) شحنة الأيون وii) حجم ثنائي القطب للجزيئات القطبية.
<h4>2. تفاعلات ثنائي القطب-ثنائي القطب</h4>

تحتوي الجزيئات القطبية على شحنة موجبة جزئية على أحد طرفيها وشحنة سالبة جزئية على الطرف الآخر من الجزيء - وهو فصل للشحنة يسمى ثنائي القطب. تسمى قوة التجاذب بين ثنائيات القطب الدائمة قوة الجذب ثنائي القطب - ثنائي القطب - القوة الكهروستاتيكية بين الطرف الموجب جزئيًا لجزيء قطبي والنهاية السالبة جزئيًا لجزيء آخر. الترابط الهيدروجيني هو نوع من التفاعل ثنائي القطب-ثنائي القطب بين الجزيئات مع الهيدروجين، المرتبطة بذرة عالية الكهروسالبية، مثل O أو N أو F. وينتج عن ذلك ذرة H مشحونة جزئيًا بشكل إيجابي على جزيء واحد (المانح لرابطة الهيدروجين) يمكن أن تتفاعل بقوة مع زوج وحيد من الإلكترونات من ذرة O أو N أو F مشحونة جزئيًا على الجزيئات المجاورة (المانح لرابطة الهيدروجين). الرابطة الهيدروجينية تزيد من درجة الغليان بشكل كبير.

<h4>3. قوى فان دير فالس وقوى تشتت لندن</h4>
أضعف القوى هي قوى فان دير فالس، والتي تعتمد على المسافات بين الجزيئات بين الذرات والجزيئات. يتم اختبار قوى تشتت لندن، وهي مجموعة فرعية من قوى فان دير فالس، نتيجة للتفاعلات بين الذرات / الجزيئات غير المشحونة بسبب التحولات المؤقتة والعفوية في توزيع الإلكترون. ويبدو أن قوة هذه القوى تزداد مع زيادة الوزن الجزيئي بسبب زيادة مساحة السطح. ونتيجة لذلك، فإن المركبات ذات الأوزان الجزيئية الأعلى سوف تغلي بشكل عام عند درجات حرارة أعلى. تجدر الإشارة إلى أن الهيدروكربون المتفرع (النيوبنتان) عادةً ما يكون له مساحة سطحية أصغر من أيزومر السلسلة المستقيمة (nالبنتان)، وبالتالي نقطة غليان أقل.

<h4>4. قابلية ذوبان المركبات العضوية في الماء</h4>
تسمى السوائل التي يمكن خلطها بشكل متجانس بأي نسبة بأنها قابلة للامتزاج. السوائل القابلة للامتزاج لها قطبية مماثلة. على سبيل المثال، الميثانول والماء كلاهما قطبيان وقادران على تكوين روابط هيدروجينية. عند الخلط، يتفاعل الميثانول والماء من خلال روابط هيدروجينية بين الجزيئات ذات قوة مماثلة لتفاعلات الميثانول - الميثانول والماء - الماء؛ وبالتالي، فهي قابلة للامتزاج. وبالمثل، فإن السوائل غير القطبية مثل الهكسان والبروم قابلة للامتزاج مع بعضها البعض من خلال قوى التشتت. تعتبر القاعدة الكيميائية "المثيل يذيب المثيل" مفيدة للتنبؤ بقابلية امتزاج المركبات. يسمى السائلان اللذان لا يختلطان إلى حد ملموس غير قابلين للامتزاج. على سبيل المثال، الهكسان غير القطبي غير قابل للامتزاج في الماء القطبي. إن قوى الجذب الضعيفة نسبيًا بين الهكسان والماء لا تتغلب بشكل كافٍ على قوى الترابط الهيدروجيني الأقوى بين جزيئات الماء.

هذا النص مقتبس من<a href="https://openstax.org/books/chemistry-2e/pages/10-1-intermolecular-forces"> Openstax, Chemistry 2e, Section 10.1: Intermolecular Forces</a>, <a href="https://openstax.org/books/chemistry-2e/pages/11-3-solubility">Section 11.3: Solubility</a>, and <a href="https://openstax.org/books/chemistry-2e/pages/10-introduction">Chapter 10: Liquids and Solids</a>.

</div>


القوى بين الجزيئات هي قوى جاذبة موجودة بين الجزيئات. إنها تملي العديد من الخصائص السائبة ، مثل نقاط الانصهار ، ونقاط الغليان ، ...

Education

JoVE Core

Organic Chemistry

الكيمياء العضوية

Unit 1

الوحدة الأولى

Covalent Bonding and Structure

الترابط التساهمي والبنية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

how intermolecular forces affect matter

Intermolecular forces are the attractions between molecules, and they help explain how matter behaves. These forces influence melting points, boiling points, and whether substances mix with one another. Water has a much higher boiling point than hexane, which shows that water has stronger intermolecular forces.

Three main kinds of intermolecular interactions are covered here. They include ion-dipole forces, dipole-dipole interactions, and van der Waals forces, which include London dispersion forces. Each type depends on how charges are arranged in or between molecules.

Ion-dipole forces are electrostatic attractions between an ion and a dipole. They are common in solutions and are important when ionic compounds such as KCl dissolve in water. Their strength depends on the charge on the ion and the size of the dipole in the polar molecule.

Dipole-dipole interactions happen between polar molecules. A polar molecule has a partial positive end and a partial negative end, which is called a dipole. Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to O, N, or F, and it can raise boiling points a great deal.

Van der Waals forces are the weakest intermolecular forces discussed here. London dispersion forces are a type of van der Waals force and arise from temporary shifts in electron distribution in uncharged atoms or molecules. These forces usually get stronger as molecular weight increases because surface area increases, so compounds with higher molecular weights tend to boil at higher temperatures. A branched hydrocarbon such as neopentane has less surface area than straight-chain n-pentane, so neopentane has the lower boiling point.

Intermolecular forces also help predict solubility in water. Liquids that mix in any proportion are called miscible, and they usually have similar polarities. Methanol and water are miscible because both are polar and can form hydrogen bonds. Nonpolar hexane and bromine are also miscible with each other through dispersion forces. The idea of “like dissolves like” helps explain why this happens. Hexane and water are immiscible because the weak attraction between them does not overcome the stronger hydrogen bonding among water molecules.

How Intermolecular Forces Affect Matter

what is organic chemistry?

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Organic chemistry focuses on carbon compounds called organic compounds. These compounds may come from living things or be made by chemists. Carbon is the main element in them, and it bonds with other carbon atoms as well as hydrogen, oxygen, nitrogen, and sulfur. Carbon can form up to four strong bonds. That ability lets carbon atoms build chains and rings of many sizes, shapes, and levels of complexity. Not every carbon-containing substance is classified as organic. Carbonates, cyanides, and...

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chemical bonds

Chemical Bonds: Types and Strength

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Molecular shape and molecular polarity can be predicted with VSEPR theory and dipole moments. Start by writing the Lewis structure of the molecule or polyatomic ion. Then count the electron groups around the central atom. Lone pairs and bonds both count as electron groups, and a single, double, or triple bond each counts as one region of electron density. Use that count to identify the electron-pair geometry. Next, use the number of lone pairs to determine the molecular structure. If more than...

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Molecular orbital theory explains how electrons are arranged in molecules. It treats electron regions in a molecule much like atomic orbitals in an atom. A molecular orbital is the region of space where a valence electron is most likely to be found. Molecular orbitals form through the linear combination of atomic orbitals, or LCAO. When atomic wave functions combine in phase, they create regions with high electron density. When they combine out of phase, they create nodes, or regions with no...

intermolecular forces and physical properties

Intermolecular forces are the attractions between molecules, and they help explain how matter behaves. These forces influence melting points, boiling points, and whether substances mix with one another. Water has a much higher boiling point than hexane, which shows that water has stronger intermolecular forces. Three main kinds of intermolecular interactions are covered here. They include ion-dipole forces, dipole-dipole interactions, and van der Waals forces, which include London dispersion...

solubility

Why Some Substances Dissolve in Water

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introduction to functional groups

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Functional groups are groups of atoms with specific chemical properties that appear within organic molecules. They are sometimes shown as "R." These groups sit along the carbon backbone of macromolecules, which can form chains or rings of carbon atoms. Functional groups help functionalize a compound. That means they can give the molecule different physical and chemical properties. In organic chemistry, this change in group structure can strongly affect how a compound behaves. Common...

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Advanced functional groups are atom clusters in organic molecules that give those molecules specific chemical properties. They are sometimes shown as "R" in formulas. By changing the atoms attached to a carbon skeleton, a functional group can make a compound behave differently in physical and chemical reactions. This topic covers several major classes of organic compounds with advanced functional groups. Aromatic hydrocarbons include benzene. Phenol is another example and is also called...

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Learn how ion-dipole, dipole-dipole, and London dispersion forces affect boiling point, melting point, and solubility in water and other liquids.

How Intermolecular Forces Affect Matter | JoVE K12

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JoVE Core Organic Chemistry explains basic concepts of stereochemistry, reactions, and mechanisms using concise and easy-to-understand animated video lessons. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

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Motion And Stability: Forces And Interactions

HS-PS2-6

Tennessee Academic Standards

Motion and Stability: Forces and Interactions

CHEM1.PS2.2

Minnesota Academic Standards in Science

9-12

1.1.1 9L.4.2.1.1

Arizona Science Standards

Physical Science

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Ions and Ionic Charges

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HS-PS1-1

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comparison-between-electrical-and-gravitational-forces

Comparison Between Electrical And Gravitational Forces

There are four fundamental forces in nature: the gravitational force, the electromagnetic force, the strong nuclear force, and the weak nuclear force. To ...



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

electric-field-of-two-equal-and-opposite-charges

Electric Field of Two Equal and Opposite Charges

Atoms generally contain the same number of positively and negatively charged particles, protons, and electrons. Hence, they are electrically neutral. ...

Electric Field

Consider two point charges, each exerting Coulomb force on the other. It is possible to describe the Coulomb interaction via an intermediate step by ...

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 ...

Electric Dipoles and Dipole Moment

Consider two charges of equal magnitude but opposite signs. If they cannot be separated by an external electric field, the system is called a permanent ...

Plan and conduct an investigation to gather evidence to compare the structure of substances at the macroscale 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 network solids (such as graphite). Examples of macro-properties of substances could include the melting point and boiling point, vapor pressure, and surface tension.

bond-dissociation-energy-and-activation-energy

Bond Dissociation Energy and Activation Energy

Bond energy is the energy required to break a bond homolytically. These values are usually expressed in units of kcal/mol or kJ/mol and are referred to as ...

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, ...

Coupled Reactions

Cellular processes such as building and breaking down complex molecules occur through stepwise chemical reactions. Some of these chemical reactions are ...

energy-diagrams-transition-states-and-intermediates

Energy Diagrams, Transition States, and Intermediates

Free-energy diagrams, or reaction coordinate diagrams, are graphs showing the energy changes that occur during a chemical reaction. The reaction ...

What is Metabolism?

Overview

Metabolism represents all of the chemical activity in a cell, including reactions that build molecules (anabolism) and those that break ...

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 ...

Non-equilibrium in the Cell

An important concept in studying metabolism and energy is that of chemical equilibrium. Most chemical reactions are reversible. They can proceed in both ...

Activation Energy

Activation energy is the minimum amount of energy necessary for a chemical reaction to move forward. The higher the activation energy, the slower the rate ...

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 ...

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 ...

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, ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

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 ...

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.

HS-PS1-4

How Intermolecular Forces Affect Matter

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