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

אינטראקציות אלקטרוסטטיות הקיימות בין מולקולות נקראות כוחות בין-מולקולריים. כוחות משיכה אלה משפיעים על תכונות פיזיקליות שונות, כגון נקודת התכה, נקודת רתיחה ומסיסות.
שלושת הסוגים העיקריים של הכוחות הבין-מולקולריים כוללים אינטראקציות יונים-דיפול חזקות בין יונים למולקולות קוטביות, אינטראקציות דיפול-דיפול בין מולקולות קוטביות, ולבסוף, החלש מכולם - כוחות פיזור - הקיים בכל המולקולות, קוטביות ולא קוטביות.
אינטראקציות יון-דיפול נפוצות בפתרונות. כאשר תרכובת יונית כמו נתרן כלורי מומסת בממס קוטבי כמו מים, היונים מתיישרים עם הקצוות הטעונים ההפוכים של מולקולות המים, ומאפשרים משיכה אלקטרוסטטית מרבית.
לחלופין, אינטראקציות דיפול-דיפול מוצגות על ידי מולקולות קוטביות עם דיפולים קבועים, כאשר הקצה החיובי של מולקולה אחת מקיים אינטראקציה אלקטרוסטטית עם הקצה השלילי של המולקולה השכנה.
כאשר אטום מימן הקשור לחמצן, חנקן או פלואור נמשך לאטום אלקטרושלילי של מולקולה שכנה, נוצר קשר מימן – סוג מיוחד של אינטראקציה בין דיפול לדיפול. יש לציין כי תרכובות המסוגלות לקשור מימן מציגות נקודות התכה ורתיחה גבוהות.
כוחות הפיזור הם תוצאה של דיפולים זמניים ונוטים לגדול עם המסה המולרית. לאטומים בעלי מסה גבוהה יותר יש יותר אלקטרונים וענני אלקטרונים גדולים יותר, מה שמוביל לכוחות פיזור מוגברים יותר. כתוצאה מכך, נדרשת יותר אנרגיה כדי להתגבר על הכוחות המושכים בין אטומים שכנים, וכתוצאה מכך נקודות רתיחה והתכה גבוהות יותר.
זה מסביר מדוע נקודות הרתיחה של האלקן גדלות עם המסה המולרית שלהן.
עם זאת, מסה מולרית אינה הקריטריון היחיד. למרות שיש לו את אותן מסות, n-pentane יש נקודת רתיחה גבוהה יותר מאשר neopentane בשל שטח הפנים גדל זמין עבור כוחות פיזור.
כוחות בין-מולקולריים חיוניים גם הם בקביעת מסיסות. נוזלים בעלי סוג ועוצמה דומים של כוחות בין-מולקולריים, כגון מים ואתנול, מסיסים לחלוטין בכל הפרופורציות או ניתנים לערבוב.
לעומת זאת, נוזלים כגון הקסאן ומים, בעלי סוגים וגדלים שונים של כוחות בין-מולקולריים, אינם מסיסים ברוב הפרופורציות או בלתי ניתנים להפרעה.
באופן כללי, הכוחות הבין-מולקולריים חלשים יחסית מכיוון שמטענים קטנים או חלקיים מתקשרים על פני מרחקים גדולים.

כוחות בין-מולקולריים ותכונות פיזיקליות

<div style="direction:rtl">
 
 <a id="_heading=h.gjdgxs">
 </a>
 כוחות בין מולקולריים הם כוחות משיכה הקיימים בין מולקולות. הם מכתיבים מספר מאפיינים בתפזורת, כגון נקודות התכה, נקודות רתיחה ומסיסות (התערבבות) של חומרים. לדוגמה, נוזל בעל נקודת רתיחה גבוהה, כמו מים (H
 
 2
 
 O, b.p. 100 מעלות צלזיוס), מפגין כוחות בין-מולקולריים חזקים יותר בהשוואה לנוזל בעל נקודת רתיחה נמוכה, כמו הקסאן (C
 
 6
 
 H
 
 14
 
 , b.p. 68.73 מעלות צלזיוס). שלושת סוגי האינטראקציות הבין-מולקולריות כוללות i) כוחות יון-דיפול, ii) אינטראקציות דיפול-דיפול, ו-iii) כוחות ואן דר ואלס, הכוללים כוחות פיזור לונדון.
 
 <ol style="padding-right: 35px; margin: 0;">
 <li style="text-align: right;">
 כוחות יון-דיפול
 </li>
 </ol>
 
 כוחות יון-דיפול הם המשיכה האלקטרוסטטית בין יון לדיפול. הם נפוצים בתמיסות וממלאים תפקיד חשוב בהמסה של תרכובות יוניות, כמו KCl, במים. החוזק של אינטראקציות יון-דיפול עומד ביחס ישר ל-i) המטען על היון ו-ii) לגודל הדיפול של מולקולות קוטביות.
 
 <ol style="padding-right: 35px; margin: 0;">
 <li style="text-align: right;">
 אינטראקציות דיפול-דיפול
 </li>
 </ol>
 
 למולקולות קוטביות יש מטען חיובי חלקי בקצה האחד ומטען שלילי חלקי בקצה השני של המולקולה - הפרדה של מטען הנקראת דיפול. כוח המשיכה בין שני דיפולים קבועים נקרא משיכה דיפול-דיפול - הכוח האלקטרוסטטי בין הקצה החיובי בחלקו של מולקולה קוטבית אחת לקצה השלילי בחלקה של אחרת. קשר מימן הוא סוג של אינטראקציה דיפול-דיפול בין מולקולות עם מימן, הקשורות לאטום אלקטרוני שלילי מאוד, כגון O, N או F. אטום H בעל מטען חיובי חלקי שנוצר על מולקולה אחת (תורם קשרי המימן) יכול לקיים אינטראקציה חזקה עם זוג בודד של אלקטרונים של אטום O, N או F בעל מטען שלילי חלקית על מולקולות סמוכות (מקבל קשרי מימן). התקשרות מימן מעלה את נקודת הרתיחה במידה ניכרת.
 
 <ol style="padding-right: 35px; margin: 0;">
 <li style="text-align: right;">
 ואן דר ואלס וכוחות פיזור לונדון
 </li>
 </ol>
 
 החלש מכל הכוחות הוא כוחות ואן דר ואלס, התלויים במרחקים הבין-מולקולריים בין אטומים למולקולות. כוחות פיזור לונדון, תת-קבוצה של כוחות ואן דר ואלס, נחווים כתוצאה מאינטראקציות בין אטומים/מולקולות לא טעונים עקב שינויים זמניים וספונטניים בחלוקת האלקטרונים. נראה שעוצמתם של כוחות אלה עולה עם הגדלת המשקל המולקולרי בגלל הגידול בשטח הפנים. כתוצאה מכך, תרכובות בעלות משקל מולקולרי גבוה יותר ירתחו בדרך כלל בטמפרטורות גבוהות יותר. ראוי לציין שלפחמימן מסועף (ניאופנטן) יש בדרך כלל שטח פנים קטן יותר מהאיזומר בעל השרשרת הישרה (n-פנטן), ולכן נקודת רתיחה נמוכה יותר.
 
 <ol style="padding-right: 35px; margin: 0;">
 <li style="text-align: right;">
 מסיסות של תרכובות אורגניות במים
 </li>
 </ol>
 
 נאמר על נוזלים שניתן לערבב בצורה הומוגנית בכל מידה שהם ניתנים לערבוב. לנוזלים המתערבבים יש קוטביות דומה. לדוגמה, מתנול ומים הם קוטביים ומסוגלים לקשור מימן. בעת ערבוב, מתנול ומים מקיימים אינטראקציות באמצעות קשרי מימן בין-מולקולריים בעלי חוזק דומה לאינטראקציות מתנול-מתנול, ומים-מים; לפיכך, הם ניתנים לערבוב. כמו כן, נוזלים לא קוטביים כמו הקסאן וברום מתמזגים זה עם זה באמצעות כוחות פיזור. האקסיומה הכימית “דומה נמס בדומה לו” שימושית לניבוי התערבבות של תרכובות. שני נוזלים שאינם מתערבבים במידה ניכרת נקראים בלתי ניתנים לערבוב. לדוגמה, הקסאן לא קוטבי אינו ניתן לערבוב במים קוטביים. כוחות משיכה חלשים יחסית בין ההקסאן למים אינם מתגברים בצורה מספקת על כוחות קשרי המימן החזקים יותר בין מולקולות מים.
 
 
 הטקסט הזה מותאם מ <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>


כוחות בין-מולקולריים הם כוחות מושכים הקיימים בין מולקולות. הם מכתיבים מספר תכונות בתפזורת, כגון נקודות התכה, נקודות רתיחה, ...

Education

JoVE Core

Organic Chemistry

כימיה אורגנית

Unit 1

יחידה 1

Covalent Bonding and Structure

קשרים קוולנטיים ומבנה

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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?

Carbon Compounds in Everyday Life

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...

electronic structure of atoms

Atomic Orbitals and Quantum Numbers

Atomic orbitals and quantum numbers describe how electrons are arranged around the nucleus. An atom has a small, positively charged nucleus with electrons surrounding it. The nucleus contains protons and neutrons, and the quantum mechanical model gives a better picture of this structure than older models. Protons carry a +1 charge and have a mass of 1.0073 amu. Neutrons have no charge and have a mass of 1.0087 amu. Electrons carry a −1 charge and have a mass of 0.00055 amu. The number of...

electron configurations

How Electrons Fill Atomic Orbitals

Electron filling in atoms follows a set order based on orbital energy. The Aufbau principle says each new electron enters the lowest-energy subshell available. The Pauli exclusion principle says no two electrons can share the same set of four quantum numbers. Hund’s rule of maximum multiplicity says electrons stay unpaired in equal-energy orbitals when possible. The order of filling follows the relative energies of the subshells. A common sequence is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.

chemical bonds

Chemical Bonds: Types and Strength

Chemical bonds help atoms reach a full valence shell like the nearest noble gas. The main bond types are ionic, covalent, and metallic. Bond energy and bond length also help explain how strong a bond is. An ionic bond forms from electrostatic attraction between cations and anions. In many cases, one atom transfers electrons to another atom, and the ions form from that transfer. Ionic bonds have no defined direction because the attraction spreads evenly through three-dimensional space. A...

polar covalent bonds

Electronegativity in Polar Covalent Bonds

Polar covalent bonds form when atoms share electrons unevenly. This happens in covalent bonds between atoms that have similar, but not identical, tendencies to attract electrons. Nonmetal atoms often make these bonds with other nonmetals. Hydrogen gas, H2, is a simple example of a covalent bond between two hydrogen atoms. A covalent bond begins when two atoms move close enough for their valence orbitals to overlap. In hydrogen, the 1s orbitals overlap and the single electrons on each atom...

lewis structures and formal charges

Lewis Structures, Bonds, and Formal Charge

Lewis structures show how atoms share electrons in covalent bonds and in polyatomic ions. Lewis symbols help draw these structures, and the periodic table helps predict how many valence electrons an atom has and how many bonds it can form to reach an octet. Group 18 elements, such as argon and helium, already have filled electron configurations. They rarely take part in chemical bonding. Atoms in group 17, such as bromine and iodine, need one more electron to reach an octet, so they can form...

vsepr theory

Molecular Shapes from Electron Pairs

Molecular shape can be predicted from the way electron pairs arrange around a central atom. Valence shell electron-pair repulsion theory, or VSEPR theory, uses a Lewis structure to count bonding pairs and lone electron pairs. The main idea is simple: electron pairs spread out as far as possible to reduce repulsion. In a molecule, the valence electrons around the central atom can be bonding pairs or lone pairs. Bonding pairs are found mainly between bonded atoms. Lone pairs stay on one atom and...

molecular geometry and dipole moments

Predicting Shape and Molecular Polarity

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...

resonance and hybrid structures

Resonance in Nitrite and Carbonate Ions

Resonance explains why some Lewis structures do not match the measured properties of a molecule or ion. When two or more Lewis structures have the same atom arrangement, the real electron distribution is an average of the structures shown. The nitrite anion, NO2−, is one example. It can be drawn in two ways, with the N–O and N=O bonds in different places. If nitrite had one single bond and one double bond, the two bond lengths should be different, because a double bond is shorter and stronger...

valence bond theory and hybridized orbitals

valence-bond-theory-and-hybridized-orbitals

Covalent Bond Overlap and Orbital Hybridization

Covalent bonds form when orbitals on two atoms overlap and their single electrons pair up. The bond is stronger when the overlap is greater. Maximum overlap happens when the orbitals meet along a direct line between the two nuclei. A sigma bond, or σ bond, is the kind of covalent bond found in a single bond in a Lewis structure. In a σ bond, electron density is concentrated along the internuclear axis. A pi bond, or π bond, forms when two p orbitals overlap side by side. In a π bond, the...

mo theory and covalent bonding

Bond Order and Molecular Orbitals

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

Solution formation depends on how solutes and solvents interact. A solution is a homogeneous mixture made of a solvent, which is the larger part, and a solute, which is the smaller part. The physical state of a solution is usually the same as the solvent. Concentration is often described as dilute for a low amount of solute or concentrated for a high amount of solute. When a solute dissolves, its particles are surrounded by solvent species. This process is called solvation. If water is the...

introduction to functional groups

Functional Groups and Organic Molecules

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...

overview of advanced functional groups

Advanced Functional Groups in Organic Chemistry

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...

key terms and concepts

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

organic chemistry

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.

motion-and-stability-forces-and-interactions

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

HS+C.P1

HS+C.P1U1.4

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 ...

the-periodic-table-and-organismal-elements

The Periodic Table And Organismal Elements

Atomic Structure

The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which ...

Electron Configurations

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

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-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 ...

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 ...

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 ...

Coulomb's Law

Experiments with electric charges have shown that if two objects each have an electric charge, they exert an electric force on each other. The magnitude ...

Electric Charges

From lightning during thunderstorms to electronic devices, the phenomenon of electromagnetism is all around us. The electromagnetic force is one of the ...

sources-and-properties-of-electric-charge

Sources and Properties of Electric Charge

All objects we see around us consist of atoms, which combine to form molecules. The lightest element in the universe is hydrogen, and a hydrogen atom ...

Types of Forces

In most situations, forces can be grouped into two categories: contact forces and field forces.&#160; Contact forces occur as a result of direct physical ...

Electric Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
An electric field is generated ...

Intermolecular Forces

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

Van der Waals Interactions

Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions ...

Chemical Bonds


Atoms participate in a chemical bond formation&#160;to acquire a completed valence-shell electron configuration similar to that of the noble gas nearest ...

Electron Behavior

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

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 ...

Ions and Ionic Charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

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 and the composition of the nucleus of atoms.  Clarification Statement: Chemistry: Examples of properties that could be predicted from patterns could include reactivity of metals, types of bonds formed, numbers of bonds formed, atomic radius, atomic mass, or reactions with oxygen. Emphasis is on main group elements and qualitative understanding of the relative trends of ionization energy and electronegativity.

HS-PS1-1

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 ...

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 ...

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 ...

Introduction to Chemical Reactions

All chemical reactions begin with a reactant, the general term for one or more substances entering the reaction. Sodium and chloride ions, for example, ...

Temperature Dependence on Reaction Rate

The Collision Theory
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. ...

stoichiometry-product-yield-and-limiting-reactants

Stoichiometry, Product Yield, and Limiting Reactants

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

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

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 ...

Dynamic Equilibrium

A reversible chemical reaction represents a chemical process that proceeds in both forward (left to right) and reverse (right to left) directions. When ...

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 Statement: Chemistry: Examples of chemical reactions could include the reaction of sodium and chlorine, carbon and oxygen, or carbon and hydrogen. Reaction classification aids in the prediction of products (e.g. synthesis, decomposition, single displacement, double displacement, and acid-base).

HS-PS1-2

Intermolecular vs Intramolecular Forces

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

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

Description

Transcript

More videos by Standards